View at EarthSky Community Photos. | Steven Bellavia in Smithfield, Virginia, captured the Cocoon Nebula on November 26, 2025. Steven wrote: “The Cocoon Nebula is a reflection and emission nebula in the constellation Cygnus, at the head of the Swan and near the boundary of the constellation Lacerta. It is about 4,000 light-years away. And the central star that illuminates it formed 100,000 years ago. The nebula is approximately 12 arc minutes across, which is a span of 15 light-years.” Thank you, Steven! See more deep-sky photos from November 2025 below.
Stunning deep-sky photos from our community
The EarthSky community has many talented astrophotographers who capture stunning images of the deep sky. We gathered some of our favorite deep-sky photos we received in November 2025 for you to enjoy. Do you have some of your own images to share? You can submit them to us here. We would love to see them!
Deep-sky photos of diffuse nebulae
View at EarthSky Community Photos. | Aquib Ali Ansari in Jaipur, Rajasthan, India, caught IC 1318, a nebulous region in the constellation Cygnus, on November 11, 2025. Aquib wrote: “This wide-field image highlights one of the richest regions of the northern Milky Way. These are the glowing hydrogen clouds and dark dust lanes surrounding the central star of the Northern Cross. In the upper right is the Crescent Nebula (NGC 6888). It’s created by fast stellar winds from a massive Wolf-Rayet star. The winds carve out a glowing bubble of ionized gas. This image reveals the faint, intricate details of this complex star-forming region.” Thank you, Aquib!View at EarthSky Community Photos. | Tameem Altameemi in the United Arab Emirates captured the Soul Nebula on November 21, 2025. Tameem wrote: “The Soul Nebula is a vast star-forming complex located about 7,500 light-years away in Cassiopeia. The nebula glows in emissions of hydrogen, oxygen and sulfur. It reveals sweeping clouds of ionized gas shaped by intense radiation and stellar winds from massive young stars. Within the nebula are several embedded star clusters and pillar-like formations sculpted over millions of years. I noticed a striking dark feature that resembles a lost astronaut drifting within the nebula’s glowing clouds … adding a human-like touch to this cosmic landscape.” Thank you, Tameem!View at EarthSky Community Photos. | Steven Bellavia in Smithfield, Virginia, captured Barnard 213, a dark nebula in Taurus, on November 14, 2025. Steven wrote: “To me, it looks like a rope, perhaps with some smoke, meandering through the stars. Dark nebulae consist of clouds of interstellar gas – primarily molecular hydrogen – and dust. These clouds are dense enough to block visible light from objects behind them.” Thank you, Steven!
More diffuse nebulae
View at EarthSky Community Photos. | Harshwardhan Pathak in Sharavasti, Uttar Pradesh, India, captured the Horsehead Nebula on November 14, 2025. Harshwardhan wrote: “The Horsehead Nebula, located in the Orion constellation, is a dark nebula approximately 1,500 light-years away. This iconic cloud of gas and dust is about 3.5 light-years across and illuminated by nearby stars, giving it a striking horsehead shape.” Thank you, Harshwardhan!View at EarthSky Community Photos. | Andy Dungan near Cotopaxi, Colorado, captured the Embryo Nebula in Perseus on November 23, 2025. Andy wrote: “This is such an unusual item to photograph. It has more color and shape than so many other nebulae and also has dark nebulae. It isn’t large. One thing interesting about astrophotography is you can’t easily determine the difference in the size of an object (as viewed from Earth) by looking at a pic. This is why I enjoy doing wide-field astrophotography as well as deep space, like this pic.” Thank you, Andy!
Even more deep-sky photos of nebulae
View at EarthSky Community Photos. | Tameem Altameemi in the United Arab Emirates captured the Fish Head Nebula on November 22, 2025. Tameem wrote: “The Fish Head Nebula is an active star-forming region located about 6,000 to 6,500 light-years away in the constellation Cassiopeia. It’s part of a larger star-forming complex and one of the most dynamic regions of massive star birth in the Milky Way.” Thank you, Tameem!View at EarthSky Community Photos. | Andy Dungan near Cotopaxi, Colorado, captured the IC 348 region of dust and nebulosity around the star Omicron Persei A on November 14, 2025. Andy wrote: “What a surprise! I don’t know how I became interested in this area. I was shocked at the colors and size of this region. There are so many exciting and unusual things out there in space. To infinity and beyond!” Thank you, Andy!
An interesting reflection nebula
View at EarthSky Community Photos. | Jelieta Walinski at Desert Bloom Observatory in St. David, Arizona, captured VdB 126, a reflection nebula in the constellation Vulpecula, on November 25, 2025. Jelieta wrote: “In the soft darkness of Vulpecula, where star-winds drift like ancient hymns, VdB 126 glows as a delicate reflection nebula … a floating lantern of cosmic dust scattering the blue light of a hidden star. Roughly 1,200 light-years from Earth, this cloud of interstellar grains becomes a quiet teacher of astrophysics, showing how dust not only obscures starlight but also paints it into ethereal color.” Thank you, Jelieta!
Deep-sky photos of faraway galaxies
View at EarthSky Community Photos. | Gwen Forrester in DeKalb County, Tennessee, captured Messier 74, in the constellation Pisces, on November 13, 2025. Gwen wrote: “Messier 74, the Phantom Galaxy, so-called because its low surface brightness makes it difficult to see. It’s 85,000 light-years across, 32 million light-years away.” Thank you, Gwen!View at EarthSky Community Photos. | Andy Dungan in Colorado captured the spiral galaxy IC 342 in the constellation Camelopardalis on November 20, 2025. Andy wrote: “This is really sort of the first of the winter galaxies. The Cigar Galaxy comes next, in a month or two, and then lots of galaxies in the vicinity of the Big Dipper. The challenge of IC 342 is how dim it is compared to many others of its size. Evidently there is a substantial amount of dust someplace in between here and the 7 to 10 million light-years to the galaxy.” Thank you, Andy!
Bottom line: Enjoy this gallery of deep-sky photos for November 2025 from our EarthSky community. If you have a great photo to share, send it in, too. We love to see them!
View at EarthSky Community Photos. | Steven Bellavia in Smithfield, Virginia, captured the Cocoon Nebula on November 26, 2025. Steven wrote: “The Cocoon Nebula is a reflection and emission nebula in the constellation Cygnus, at the head of the Swan and near the boundary of the constellation Lacerta. It is about 4,000 light-years away. And the central star that illuminates it formed 100,000 years ago. The nebula is approximately 12 arc minutes across, which is a span of 15 light-years.” Thank you, Steven! See more deep-sky photos from November 2025 below.
Stunning deep-sky photos from our community
The EarthSky community has many talented astrophotographers who capture stunning images of the deep sky. We gathered some of our favorite deep-sky photos we received in November 2025 for you to enjoy. Do you have some of your own images to share? You can submit them to us here. We would love to see them!
Deep-sky photos of diffuse nebulae
View at EarthSky Community Photos. | Aquib Ali Ansari in Jaipur, Rajasthan, India, caught IC 1318, a nebulous region in the constellation Cygnus, on November 11, 2025. Aquib wrote: “This wide-field image highlights one of the richest regions of the northern Milky Way. These are the glowing hydrogen clouds and dark dust lanes surrounding the central star of the Northern Cross. In the upper right is the Crescent Nebula (NGC 6888). It’s created by fast stellar winds from a massive Wolf-Rayet star. The winds carve out a glowing bubble of ionized gas. This image reveals the faint, intricate details of this complex star-forming region.” Thank you, Aquib!View at EarthSky Community Photos. | Tameem Altameemi in the United Arab Emirates captured the Soul Nebula on November 21, 2025. Tameem wrote: “The Soul Nebula is a vast star-forming complex located about 7,500 light-years away in Cassiopeia. The nebula glows in emissions of hydrogen, oxygen and sulfur. It reveals sweeping clouds of ionized gas shaped by intense radiation and stellar winds from massive young stars. Within the nebula are several embedded star clusters and pillar-like formations sculpted over millions of years. I noticed a striking dark feature that resembles a lost astronaut drifting within the nebula’s glowing clouds … adding a human-like touch to this cosmic landscape.” Thank you, Tameem!View at EarthSky Community Photos. | Steven Bellavia in Smithfield, Virginia, captured Barnard 213, a dark nebula in Taurus, on November 14, 2025. Steven wrote: “To me, it looks like a rope, perhaps with some smoke, meandering through the stars. Dark nebulae consist of clouds of interstellar gas – primarily molecular hydrogen – and dust. These clouds are dense enough to block visible light from objects behind them.” Thank you, Steven!
More diffuse nebulae
View at EarthSky Community Photos. | Harshwardhan Pathak in Sharavasti, Uttar Pradesh, India, captured the Horsehead Nebula on November 14, 2025. Harshwardhan wrote: “The Horsehead Nebula, located in the Orion constellation, is a dark nebula approximately 1,500 light-years away. This iconic cloud of gas and dust is about 3.5 light-years across and illuminated by nearby stars, giving it a striking horsehead shape.” Thank you, Harshwardhan!View at EarthSky Community Photos. | Andy Dungan near Cotopaxi, Colorado, captured the Embryo Nebula in Perseus on November 23, 2025. Andy wrote: “This is such an unusual item to photograph. It has more color and shape than so many other nebulae and also has dark nebulae. It isn’t large. One thing interesting about astrophotography is you can’t easily determine the difference in the size of an object (as viewed from Earth) by looking at a pic. This is why I enjoy doing wide-field astrophotography as well as deep space, like this pic.” Thank you, Andy!
Even more deep-sky photos of nebulae
View at EarthSky Community Photos. | Tameem Altameemi in the United Arab Emirates captured the Fish Head Nebula on November 22, 2025. Tameem wrote: “The Fish Head Nebula is an active star-forming region located about 6,000 to 6,500 light-years away in the constellation Cassiopeia. It’s part of a larger star-forming complex and one of the most dynamic regions of massive star birth in the Milky Way.” Thank you, Tameem!View at EarthSky Community Photos. | Andy Dungan near Cotopaxi, Colorado, captured the IC 348 region of dust and nebulosity around the star Omicron Persei A on November 14, 2025. Andy wrote: “What a surprise! I don’t know how I became interested in this area. I was shocked at the colors and size of this region. There are so many exciting and unusual things out there in space. To infinity and beyond!” Thank you, Andy!
An interesting reflection nebula
View at EarthSky Community Photos. | Jelieta Walinski at Desert Bloom Observatory in St. David, Arizona, captured VdB 126, a reflection nebula in the constellation Vulpecula, on November 25, 2025. Jelieta wrote: “In the soft darkness of Vulpecula, where star-winds drift like ancient hymns, VdB 126 glows as a delicate reflection nebula … a floating lantern of cosmic dust scattering the blue light of a hidden star. Roughly 1,200 light-years from Earth, this cloud of interstellar grains becomes a quiet teacher of astrophysics, showing how dust not only obscures starlight but also paints it into ethereal color.” Thank you, Jelieta!
Deep-sky photos of faraway galaxies
View at EarthSky Community Photos. | Gwen Forrester in DeKalb County, Tennessee, captured Messier 74, in the constellation Pisces, on November 13, 2025. Gwen wrote: “Messier 74, the Phantom Galaxy, so-called because its low surface brightness makes it difficult to see. It’s 85,000 light-years across, 32 million light-years away.” Thank you, Gwen!View at EarthSky Community Photos. | Andy Dungan in Colorado captured the spiral galaxy IC 342 in the constellation Camelopardalis on November 20, 2025. Andy wrote: “This is really sort of the first of the winter galaxies. The Cigar Galaxy comes next, in a month or two, and then lots of galaxies in the vicinity of the Big Dipper. The challenge of IC 342 is how dim it is compared to many others of its size. Evidently there is a substantial amount of dust someplace in between here and the 7 to 10 million light-years to the galaxy.” Thank you, Andy!
Bottom line: Enjoy this gallery of deep-sky photos for November 2025 from our EarthSky community. If you have a great photo to share, send it in, too. We love to see them!
Ask someone on Earth for the time and they can give you an exact answer. That’s thanks to our planet’s intricate timekeeping system, built with atomic clocks, GPS satellites and high-speed telecommunications networks.
But Einstein showed us clocks don’t tick at the same rate across the universe. Clocks will run slightly faster or slower depending on the strength of gravity in their environment. And that makes it tricky to synchronize our watches here on Earth, let alone across the vast solar system. If humans want to establish a long-term presence on the red planet, scientists need to know: What time is it on Mars?
For the first time, physicists at the National Institute of Standards and Technology (NIST) have calculated a precise answer. On average, clocks on Mars will tick 477 microseconds (millionths of a second) faster than on Earth per day. However, Mars’ eccentric orbit and the gravity from its celestial neighbors can increase or decrease this amount by as much as 226 microseconds a day over the course of the Martian year. These findings, which the peer-reviewedThe Astronomical Journalpublished on December 1, 2025, follow a 2024 paper in which NIST physicists developed a plan for precise timekeeping on the moon.
Knowing how clocks will tick on Mars is a stepping stone for future space missions, said NIST physicist Bijunath Patla. As NASA plans Mars exploration missions, understanding time on our planetary neighbor will help synchronize navigation and communication across our solar system. Patla said:
The time is just right for the moon and Mars. This is the closest we have been to realizing the science fiction vision of expanding across the solar system.
What time is it on Mars? The Earth-orbiting Hubble telescope snapped this picture on June 26, 2001, when Mars was approximately 43 million miles (68 million km) from Earth – its closest approach to our planet since 1988. Image via J. Bell/ P. James/ M. Wolff/ A. Lubenow/ J. Neubert / ESAHubble.org.
Mars time zone
Martian days and years are longer than those on Earth. The planet’s day, or full rotation on its axis, is 40 minutes longer than Earth’s. And it takes 687 days to complete its orbit around the sun, compared with Earth’s 365 days. But scientists needed to know how fast or slow each second passes on Mars compared with Earth.
If you were to land on the surface of Mars with an atomic clock, it would still tick the same way it would on Earth. But if you compare the Mars clock with one on Earth, they will be out of sync. The challenge is to determine how much Mars’ time is offset from Earth’s, almost like calculating a time-zone difference.
That was much trickier than NIST physicists had expected. Einstein’s theory of relativity states that the strength of gravity affects the passage of time. Clocks tick slower where gravity is stronger, and faster where gravity is weaker. The velocity of a planet’s orbit will also cause clocks to tick slower or faster.
A reference point on Mars
NIST chose a point on the Martian surface to act as a reference, sort of like sea level at the equator on Earth. Thanks to years of data collected from Mars missions, Patla and fellow NIST physicist Neil Ashby could estimate gravity on the surface of the planet, which is five times weaker than Earth’s.
But they needed to figure in more than just Mars’ gravity. Our solar system has other massive bodies that pull on each other. The sun alone accounts for more than 99% of the mass in our solar system. Mars’ position in the solar system — its distance from the sun, its neighbors like Earth, the moon, Jupiter and Saturn — pulls it into a more eccentric, elongated orbit. The Earth’s and moon’s orbits are relatively constant; time on the moon is consistently 56 microseconds faster than time on Earth.
Patla explained:
But for Mars, that’s not the case. Its distance from the sun and its eccentric orbit make the variations in time larger. A three-body problem is extremely complicated. Now we’re dealing with four: the Sun, Earth, the moon and Mars. The heavy lifting was more challenging than I initially thought.
After taking all these effects into consideration — Martian surface gravity, Mars’ eccentric orbit, the effect of the sun, the Earth and the moon on Mars — Patla and Ashby arrived at their answer.
An answer to what time is it on Mars
Maybe 477 millionths of a second doesn’t sound like a lot … it’s about a thousandth of the time it takes to blink. But accounting for tiny time differences is key to developing communications networks. 5G networks, for example, need to be accurate to within a tenth of a microsecond.
Right now, communications between Earth and Mars are delayed anywhere from four to 24 minutes (sometimes more). It’s almost like pre-telegram communications, Patla explained. People delivered handwritten letters to a ship, which crossed the ocean, and then waited weeks or months for another ship to deliver the reply.
Having a framework for timing between planets paves the way toward creating synchronized networks across vast distances. Patla said:
If you get synchronization, it will be almost like real-time communication without any loss of information. You don’t have to wait to see what happens.
Preparing for Mars
Those networks are a long way from reality; so are long-term human and robotic Mars missions, Ashby pointed out. Studying these issues helps scientists prepare for all the variables they will encounter. Ashby said:
It may be decades before the surface of Mars is covered by the tracks of wandering rovers, but it is useful now to study the issues involved in establishing navigation systems on other planets and moons. Like current global navigation systems like GPS, these systems will depend on accurate clocks, and the effects on clock rates can be analyzed with the help of Einstein’s general theory of relativity.
There is also scientific value to this knowledge, Patla added. Understanding how clocks will tick on far-flung planets is new information and builds on Einstein’s theories of special and general relativity. Patla said:
It’s good to know for the first time what is happening on Mars timewise. Nobody knew that before. It improves our knowledge of the theory itself, the theory of how clocks tick and relativity. The passage of time is fundamental to the theory of relativity: how you realize it, how you calculate it, and what influences it. These may seem like simple concepts, but they can be quite complicated to calculate.
Finding the exact time on Mars – in contrast to Earth – poses a challenging question that needs to be answered for future explorers of our solar system. Image via TeeFarm/ Pixabay/ NASA/ Earthsky.
Bottom line: What time is it on Mars? The time difference between Mars and Earth is a complicated puzzle. But it’s necessary to solve for future explorations.
Ask someone on Earth for the time and they can give you an exact answer. That’s thanks to our planet’s intricate timekeeping system, built with atomic clocks, GPS satellites and high-speed telecommunications networks.
But Einstein showed us clocks don’t tick at the same rate across the universe. Clocks will run slightly faster or slower depending on the strength of gravity in their environment. And that makes it tricky to synchronize our watches here on Earth, let alone across the vast solar system. If humans want to establish a long-term presence on the red planet, scientists need to know: What time is it on Mars?
For the first time, physicists at the National Institute of Standards and Technology (NIST) have calculated a precise answer. On average, clocks on Mars will tick 477 microseconds (millionths of a second) faster than on Earth per day. However, Mars’ eccentric orbit and the gravity from its celestial neighbors can increase or decrease this amount by as much as 226 microseconds a day over the course of the Martian year. These findings, which the peer-reviewedThe Astronomical Journalpublished on December 1, 2025, follow a 2024 paper in which NIST physicists developed a plan for precise timekeeping on the moon.
Knowing how clocks will tick on Mars is a stepping stone for future space missions, said NIST physicist Bijunath Patla. As NASA plans Mars exploration missions, understanding time on our planetary neighbor will help synchronize navigation and communication across our solar system. Patla said:
The time is just right for the moon and Mars. This is the closest we have been to realizing the science fiction vision of expanding across the solar system.
What time is it on Mars? The Earth-orbiting Hubble telescope snapped this picture on June 26, 2001, when Mars was approximately 43 million miles (68 million km) from Earth – its closest approach to our planet since 1988. Image via J. Bell/ P. James/ M. Wolff/ A. Lubenow/ J. Neubert / ESAHubble.org.
Mars time zone
Martian days and years are longer than those on Earth. The planet’s day, or full rotation on its axis, is 40 minutes longer than Earth’s. And it takes 687 days to complete its orbit around the sun, compared with Earth’s 365 days. But scientists needed to know how fast or slow each second passes on Mars compared with Earth.
If you were to land on the surface of Mars with an atomic clock, it would still tick the same way it would on Earth. But if you compare the Mars clock with one on Earth, they will be out of sync. The challenge is to determine how much Mars’ time is offset from Earth’s, almost like calculating a time-zone difference.
That was much trickier than NIST physicists had expected. Einstein’s theory of relativity states that the strength of gravity affects the passage of time. Clocks tick slower where gravity is stronger, and faster where gravity is weaker. The velocity of a planet’s orbit will also cause clocks to tick slower or faster.
A reference point on Mars
NIST chose a point on the Martian surface to act as a reference, sort of like sea level at the equator on Earth. Thanks to years of data collected from Mars missions, Patla and fellow NIST physicist Neil Ashby could estimate gravity on the surface of the planet, which is five times weaker than Earth’s.
But they needed to figure in more than just Mars’ gravity. Our solar system has other massive bodies that pull on each other. The sun alone accounts for more than 99% of the mass in our solar system. Mars’ position in the solar system — its distance from the sun, its neighbors like Earth, the moon, Jupiter and Saturn — pulls it into a more eccentric, elongated orbit. The Earth’s and moon’s orbits are relatively constant; time on the moon is consistently 56 microseconds faster than time on Earth.
Patla explained:
But for Mars, that’s not the case. Its distance from the sun and its eccentric orbit make the variations in time larger. A three-body problem is extremely complicated. Now we’re dealing with four: the Sun, Earth, the moon and Mars. The heavy lifting was more challenging than I initially thought.
After taking all these effects into consideration — Martian surface gravity, Mars’ eccentric orbit, the effect of the sun, the Earth and the moon on Mars — Patla and Ashby arrived at their answer.
An answer to what time is it on Mars
Maybe 477 millionths of a second doesn’t sound like a lot … it’s about a thousandth of the time it takes to blink. But accounting for tiny time differences is key to developing communications networks. 5G networks, for example, need to be accurate to within a tenth of a microsecond.
Right now, communications between Earth and Mars are delayed anywhere from four to 24 minutes (sometimes more). It’s almost like pre-telegram communications, Patla explained. People delivered handwritten letters to a ship, which crossed the ocean, and then waited weeks or months for another ship to deliver the reply.
Having a framework for timing between planets paves the way toward creating synchronized networks across vast distances. Patla said:
If you get synchronization, it will be almost like real-time communication without any loss of information. You don’t have to wait to see what happens.
Preparing for Mars
Those networks are a long way from reality; so are long-term human and robotic Mars missions, Ashby pointed out. Studying these issues helps scientists prepare for all the variables they will encounter. Ashby said:
It may be decades before the surface of Mars is covered by the tracks of wandering rovers, but it is useful now to study the issues involved in establishing navigation systems on other planets and moons. Like current global navigation systems like GPS, these systems will depend on accurate clocks, and the effects on clock rates can be analyzed with the help of Einstein’s general theory of relativity.
There is also scientific value to this knowledge, Patla added. Understanding how clocks will tick on far-flung planets is new information and builds on Einstein’s theories of special and general relativity. Patla said:
It’s good to know for the first time what is happening on Mars timewise. Nobody knew that before. It improves our knowledge of the theory itself, the theory of how clocks tick and relativity. The passage of time is fundamental to the theory of relativity: how you realize it, how you calculate it, and what influences it. These may seem like simple concepts, but they can be quite complicated to calculate.
Finding the exact time on Mars – in contrast to Earth – poses a challenging question that needs to be answered for future explorers of our solar system. Image via TeeFarm/ Pixabay/ NASA/ Earthsky.
Bottom line: What time is it on Mars? The time difference between Mars and Earth is a complicated puzzle. But it’s necessary to solve for future explorations.
View at EarthSky Community Photos. | Lynzie Flynn in California submitted this photo on November 24, 2024, and wrote: “A beautiful, graceful small egret is very active in its feeding behaviors. They forage for food by shuffling their feet in the mud to bring up small fish and invertebrates in shallow water. Its legs are black but the feet are bright gold. They nest in colonies in trees, shrubs, mangroves, sometimes on or near the ground in marshes. This is one of my favorite birds to photograph. They are very entertaining, especially when juveniles.” Thank you, Lynzie! Find out how to join the Audubon Christmas Bird Count below.
The Audubon Society’s Christmas Bird Count is one of the longest-running citizen science projects. It had a modest beginning on Christmas Day in 1900. And it has since become a strong data-gathering project to study bird population trends. This year’s count – the 126th – runs from December 14, 2025, to January 5, 2026. You have to sign up in advance, and the signup has already begun. Go here to sign up for the Christmas Bird Count 2025.
The Christmas Bird Count is a carefully run event. Each count site is a 15-mile (24-km) wide circle; you can see what it looks like by zooming in on this map to inspect a region near you. Counts for each circle are organized by a “circle compiler.” On the day of the count (set by the circle’s compiler), people head out to designated routes within a circle to count every species and number of birds that they see and hear during the day. And, if you live within the range of a count site, you can also tally the birds you see in your yard and at the feeder.
View at EarthSky Community Photos. | Lynzie Flynn in California, captured this image on November 24, 2024, and wrote: “The belted kingfisher is often perched on a high snag or rock or anyplace that gives it a good vantage point. It forages by plunging headfirst into water, capturing fish near surface with its bill. I’ve been watching for this kingfisher each time I go to this particular location. Birds are pretty territorial and they tend to perch in the same few places. I could go back a month from now and it’s likely I’d see this same bird on the same perch or close to it.” Thank you, Lynzie!
To participate in the count – it’s free – you need to sign up with a local circle compiler at the Audubon’s website. If you’re a beginning birder, you’ll be matched up with a more experienced birder. Make sure you register early, because the compiler will need time to organize the event.
In addition, you can share your bird count photographs and experiences on social media with the hashtag #ChristmasBirdCount. We here at EarthSky would love to have you send us your photographs, too!
Audubon Christmas Bird Count history
In some parts of the U.S., there used to be bird-hunting competitions on Christmas Day. However, Frank M. Chapman, an ornithologist at the American Museum of Natural History, came up with an alternative, an activity to count birds in a given area each Christmas to build up a record of their numbers.
That first count was in 1900. Overall, 27 birders conducted counts at 25 sites, tallying about 89 bird species.
Since then, the Christmas Bird Count has come a long way. It has continued annually since the inaugural event, growing in volunteers and census sites. For instance, the 125th Christmas Bird Count took place from December 14, 2024, to January 5, 2025. That count occurred at 2,693 locations, with 83,186 volunteers in the U.S., Canada, Latin America, the Caribbean and Pacific Islands. Altogether, volunteers observed a total of 2,380 bird species.
View at EarthSky Community Photos. | Cecille Kennedy captured this in Oregon on November 13, 2024, and wrote: “Anna’s hummingbird resting on a blackberry twig. In certain lighting its gorget or neck and head feathers flash iridescent colors. Anna’s hummingbird is the only hummingbird species to stay all winter at the Oregon coast.” Thank you, Cecille.
What have we learned from these counts?
Additionally, Audubon and other research groups use Christmas Bird Count data to monitor population trends that will help guide conservation efforts. To date, scientists have published more than 300 peer-reviewed studies based on this data. The data are also used by federal agencies to craft policy on bird conservation.
Each annual count provides a snapshot of the birds at a given time and place. It’s hard to draw conclusions from one year to the next, because changes happen gradually. To understand trends, scientists do a statistical analysis of data taken over several years.
Warning signs of environmental degradation show up in declines of bird populations in some types of habitats. For instance, the sharpest declines in bird populations have been in grassland habitats, followed by coastal habitats.
Bird census data also inform scientists about the effects of climate change on wildlife. National Audubon scientists predict some species of birds in North America will be affected by climate change.
Bottom line: Audubon’s 126th Christmas Bird Count will take place from December 14, 2025, to January 5, 2026. You can join in to help collect important data about birds. Find out how to join the Audubon Christmas Bird Count.
View at EarthSky Community Photos. | Lynzie Flynn in California submitted this photo on November 24, 2024, and wrote: “A beautiful, graceful small egret is very active in its feeding behaviors. They forage for food by shuffling their feet in the mud to bring up small fish and invertebrates in shallow water. Its legs are black but the feet are bright gold. They nest in colonies in trees, shrubs, mangroves, sometimes on or near the ground in marshes. This is one of my favorite birds to photograph. They are very entertaining, especially when juveniles.” Thank you, Lynzie! Find out how to join the Audubon Christmas Bird Count below.
The Audubon Society’s Christmas Bird Count is one of the longest-running citizen science projects. It had a modest beginning on Christmas Day in 1900. And it has since become a strong data-gathering project to study bird population trends. This year’s count – the 126th – runs from December 14, 2025, to January 5, 2026. You have to sign up in advance, and the signup has already begun. Go here to sign up for the Christmas Bird Count 2025.
The Christmas Bird Count is a carefully run event. Each count site is a 15-mile (24-km) wide circle; you can see what it looks like by zooming in on this map to inspect a region near you. Counts for each circle are organized by a “circle compiler.” On the day of the count (set by the circle’s compiler), people head out to designated routes within a circle to count every species and number of birds that they see and hear during the day. And, if you live within the range of a count site, you can also tally the birds you see in your yard and at the feeder.
View at EarthSky Community Photos. | Lynzie Flynn in California, captured this image on November 24, 2024, and wrote: “The belted kingfisher is often perched on a high snag or rock or anyplace that gives it a good vantage point. It forages by plunging headfirst into water, capturing fish near surface with its bill. I’ve been watching for this kingfisher each time I go to this particular location. Birds are pretty territorial and they tend to perch in the same few places. I could go back a month from now and it’s likely I’d see this same bird on the same perch or close to it.” Thank you, Lynzie!
To participate in the count – it’s free – you need to sign up with a local circle compiler at the Audubon’s website. If you’re a beginning birder, you’ll be matched up with a more experienced birder. Make sure you register early, because the compiler will need time to organize the event.
In addition, you can share your bird count photographs and experiences on social media with the hashtag #ChristmasBirdCount. We here at EarthSky would love to have you send us your photographs, too!
Audubon Christmas Bird Count history
In some parts of the U.S., there used to be bird-hunting competitions on Christmas Day. However, Frank M. Chapman, an ornithologist at the American Museum of Natural History, came up with an alternative, an activity to count birds in a given area each Christmas to build up a record of their numbers.
That first count was in 1900. Overall, 27 birders conducted counts at 25 sites, tallying about 89 bird species.
Since then, the Christmas Bird Count has come a long way. It has continued annually since the inaugural event, growing in volunteers and census sites. For instance, the 125th Christmas Bird Count took place from December 14, 2024, to January 5, 2025. That count occurred at 2,693 locations, with 83,186 volunteers in the U.S., Canada, Latin America, the Caribbean and Pacific Islands. Altogether, volunteers observed a total of 2,380 bird species.
View at EarthSky Community Photos. | Cecille Kennedy captured this in Oregon on November 13, 2024, and wrote: “Anna’s hummingbird resting on a blackberry twig. In certain lighting its gorget or neck and head feathers flash iridescent colors. Anna’s hummingbird is the only hummingbird species to stay all winter at the Oregon coast.” Thank you, Cecille.
What have we learned from these counts?
Additionally, Audubon and other research groups use Christmas Bird Count data to monitor population trends that will help guide conservation efforts. To date, scientists have published more than 300 peer-reviewed studies based on this data. The data are also used by federal agencies to craft policy on bird conservation.
Each annual count provides a snapshot of the birds at a given time and place. It’s hard to draw conclusions from one year to the next, because changes happen gradually. To understand trends, scientists do a statistical analysis of data taken over several years.
Warning signs of environmental degradation show up in declines of bird populations in some types of habitats. For instance, the sharpest declines in bird populations have been in grassland habitats, followed by coastal habitats.
Bird census data also inform scientists about the effects of climate change on wildlife. National Audubon scientists predict some species of birds in North America will be affected by climate change.
Bottom line: Audubon’s 126th Christmas Bird Count will take place from December 14, 2025, to January 5, 2026. You can join in to help collect important data about birds. Find out how to join the Audubon Christmas Bird Count.
Find the Andromeda Galaxy (M31) by star-hopping from the Great Square of Pegasus. Chart via Chelynne Campion/ EarthSky.
Tonight, try star-hopping to the famous Andromeda galaxy – the large spiral galaxy next door to our Milky Way – from the Great Square of Pegasus. Are you ready?
First, look overhead for the four stars of the Great Square. You’ll find them high in the sky a few hours after sunset around the December solstice. While the Great Square will sink toward the western horizon as evening deepens, this famous pattern of stars will remain in view until after midnight (at mid-northern latitudes).
Also, keep in mind the Great Square is so large that your hand can slip in between any two Great Square stars. By the way, you hold your hand at arm’s length to measure distances on the sky’s dome.
Find the Andromeda Galaxy (M31) by star-hopping from the Great Square of Pegasus. Chart via Stellarium.org. Used with permission.
First, focus on the top star of the Great Square on the above sky chart. Next, if you look carefully, you’ll see the constellation Andromeda as two streamers of stars jutting up from this uppermost Great Square star. Also, the two streamers mimic the shape of a cornucopia or a bugle.
Then, go to the second star upward on each streamer: Mirach and Mu Andromedae (abbreviated Mu on the sky chart). After that, draw an imaginary line from Mirach through Mu, going twice the Mirach/Mu distance. Now, you’ve just landed on the Andromeda Galaxy!
In fact, on a dark night, the Andromeda Galaxy looks like a faint, blurry patch of light or a smudge on the sky. If you can’t see it with the unaided eye, your sky might not be dark enough.
Binoculars enhance the view
Binoculars are an excellent choice for beginners to observe the Andromeda galaxy, because they are so easy to point. As you stand beneath a dark sky, locate the galaxy with your eye first. Then slowly bring the binoculars up to your eyes so that the galaxy comes into binocular view. If that doesn’t work for you, try sweeping the area with your binoculars. Go slowly, and be sure your eyes are dark-adapted. The galaxy will appear as a fuzzy patch to the eye. Naturally, it’ll appear brighter in binoculars. And can you see that its central region is more concentrated?
With the eye, binoculars, or with a backyard telescope, the Andromeda galaxy won’t look like the images from famous telescopes and observatories. But it will be beautiful. Plus, it’ll take your breath away.
Try binoculars for a better view!
The Andromeda Galaxy from our Community Photos
View at EarthSky Community Photos. | Aquib Ali Ansari in Jaipur, Rajasthan, India, captured Messier 31, the Andromeda Galaxy, on September 26, 2025. Thank you, Aquib!View at EarthSky Community Photos. | Ernest Jacobs captured this image on September 20, 2025, from New York and wrote: “Hard to believe it has been just over 100 years since humanity established that the spiral nebulae they were observing were in fact other galaxies. Edwin Hubble provided the critical evidence observations of M31. This is a favorite target for visual observation as well as imaging.” Thank you, Ernest!
Bottom line: The four stars of the Great Square of Pegasus are easy to find, and they can help you locate the Andromeda galaxy. Are you ready? Let’s star-hop!
Find the Andromeda Galaxy (M31) by star-hopping from the Great Square of Pegasus. Chart via Chelynne Campion/ EarthSky.
Tonight, try star-hopping to the famous Andromeda galaxy – the large spiral galaxy next door to our Milky Way – from the Great Square of Pegasus. Are you ready?
First, look overhead for the four stars of the Great Square. You’ll find them high in the sky a few hours after sunset around the December solstice. While the Great Square will sink toward the western horizon as evening deepens, this famous pattern of stars will remain in view until after midnight (at mid-northern latitudes).
Also, keep in mind the Great Square is so large that your hand can slip in between any two Great Square stars. By the way, you hold your hand at arm’s length to measure distances on the sky’s dome.
Find the Andromeda Galaxy (M31) by star-hopping from the Great Square of Pegasus. Chart via Stellarium.org. Used with permission.
First, focus on the top star of the Great Square on the above sky chart. Next, if you look carefully, you’ll see the constellation Andromeda as two streamers of stars jutting up from this uppermost Great Square star. Also, the two streamers mimic the shape of a cornucopia or a bugle.
Then, go to the second star upward on each streamer: Mirach and Mu Andromedae (abbreviated Mu on the sky chart). After that, draw an imaginary line from Mirach through Mu, going twice the Mirach/Mu distance. Now, you’ve just landed on the Andromeda Galaxy!
In fact, on a dark night, the Andromeda Galaxy looks like a faint, blurry patch of light or a smudge on the sky. If you can’t see it with the unaided eye, your sky might not be dark enough.
Binoculars enhance the view
Binoculars are an excellent choice for beginners to observe the Andromeda galaxy, because they are so easy to point. As you stand beneath a dark sky, locate the galaxy with your eye first. Then slowly bring the binoculars up to your eyes so that the galaxy comes into binocular view. If that doesn’t work for you, try sweeping the area with your binoculars. Go slowly, and be sure your eyes are dark-adapted. The galaxy will appear as a fuzzy patch to the eye. Naturally, it’ll appear brighter in binoculars. And can you see that its central region is more concentrated?
With the eye, binoculars, or with a backyard telescope, the Andromeda galaxy won’t look like the images from famous telescopes and observatories. But it will be beautiful. Plus, it’ll take your breath away.
Try binoculars for a better view!
The Andromeda Galaxy from our Community Photos
View at EarthSky Community Photos. | Aquib Ali Ansari in Jaipur, Rajasthan, India, captured Messier 31, the Andromeda Galaxy, on September 26, 2025. Thank you, Aquib!View at EarthSky Community Photos. | Ernest Jacobs captured this image on September 20, 2025, from New York and wrote: “Hard to believe it has been just over 100 years since humanity established that the spiral nebulae they were observing were in fact other galaxies. Edwin Hubble provided the critical evidence observations of M31. This is a favorite target for visual observation as well as imaging.” Thank you, Ernest!
Bottom line: The four stars of the Great Square of Pegasus are easy to find, and they can help you locate the Andromeda galaxy. Are you ready? Let’s star-hop!
View at EarthSky Community Photos. | Cecille Kennedy captured these crashing ocean waves in Oregon on December 14, 2024, the day of a full moon. Cecille wrote: “It is the time of king tides at the Oregon coast. The tides get higher than other times of the year when the sun, moon and Earth are in alignment.” Thank you, Cecille!
Today – December 4, 2025 – is the full Cold Moon. Full moons occur when the Earth, moon and sun are most aligned in space, with the moon opposite the sun and the Earth in the middle. The full Cold Moon will fall at 23:14 UTC today and it’s a supermoon. And that’s just a little over 12 hours after the moon reaches perigee, its closest point to Earth for this month. So, today’s moon is a full supermoon, and the 2nd closest full moon of 2025.
The full moon will rise tonight opposite the sunset. It will be highest in the sky around midnight and set opposite the sunrise tomorrow morning. And Earth’s oceans will feel the double whammy of the sun and moon.
Especially if you live along a coast, you might know that the highest tides – sometimes called perigean tides, or king tides or even supermoon tides – tend to fall on the day or so after a new or full supermoon. Watch for these high tides for a few days.
Around each new moon and full moon – when the sun, Earth and moon are located more or less on a line in space – the range between high and low tides is greatest. These are perigean tides, also known as king tides or supermoon tides. Image via NOAA/ National Ocean Service.
Supermoons in 2025
December’s full supermoon is the 3rd – and 2nd closest – of four full supermoons in a row. We’ll have one more full supermoon in January 2026.
And what about new supermoons? In 2025, we had five new supermoons in a row. They were in February, March, April, May and June. The new supermoon in March was the closest new moon of 2025.
What are spring tides?
In most places, but not everywhere, there are two high tides and two low tides a day. The difference in height between high and low tides varies, as the moon waxes and wanes from new to full and back to new again. The moon and sun are primarily responsible for the rising and falling of ocean tides. However, for any particular place on Earth’s surface, the height of the tides and their fluctuation in time also depend on the shape of your specific beach and the angle of the seabed leading up to your beach. Plus your larger coastline and the prevailing ocean currents and winds.
Around each new moon and full moon, the sun, Earth and moon lie more or less along a line in space. Then the pull on the tides increases, because the gravity of the sun reinforces the moon’s gravity. In fact, the height of the average solar tide is about 50% of the average lunar tide.
Thus, at new moon or full moon, the tide’s range is at its maximum. This is the spring tide: the highest (and lowest) tide. Spring tides are not named for the season. This is spring in the sense of jump, burst forth, rise.
So, spring tides bring the most extreme high and low tides every month. And they always happen – every month – around full and new moon.
Why?
When the new moon or full moon closely aligns with perigee – the closest point to Earth in the moon’s orbit – then we have a supermoon and extra-large spring tides.
In 2018, the January 1-2 full moon closely aligned with perigee to bring forth especially high tides. As it happened, on the day after the January 1-2 supermoon, Storm Eleanor hit Europe with winds of up to 100 mph (160 km/h). The wind and extra-high tides caused flooding, hampered travel, injured and killed people and left tens of thousands of homes without power across the U.K., Ireland and other parts of Europe. No doubt the extra-high tides contributed to the severity of the storm. Read more: High tides and winter storms (2018).
Why are the tides at their strongest around supermoons? It’s simply because the moon is at its closest to Earth, and thus the Earth’s oceans are feeling the pull of the moon’s gravity most powerfully.
Should you expect these highest tides on the exact day of a supermoon? Probably not. The highest tides tend to follow the supermoon (or any new or full moon) by a day or two.
What about flooding?
Do the most extreme high tides – those bringing floods – always occur at supermoons? Not necessarily. It’s when a spring tide coincides with a time of heavy winds and rain – flooding due to a weather extreme – that the most extreme flooding occurs.
Spring tides and neap tides coincide with particular phases of the moon. Around each new moon and full moon – when the sun, Earth, and moon align in space – the range between high and low tides is greatest. These are the spring tides. Around each first quarter moon and last quarter moon – when the sun and moon are at a right angle – the range between high and low tides is the least. These are the neap tides. Image via NOAA/ National Ocean Service.View at EarthSky Community Photos. | Christy Mandeville of Indian Shores, Florida, captured this image of ocean waves surging onto a beach on June 4, 2023. Thank you, Christy!
What are neap tides?
There’s about a seven-day interval between spring tides and neap tides, when the tide’s range is at its minimum. Neap tides occur halfway between each new and full moon – at the first quarter and last quarter moon phase – when the sun and moon are at right angles as seen from Earth. Then the sun’s gravity is working against the gravity of the moon, as the moon pulls on the sea. Neap tides happen approximately twice a month, once around first quarter moon and once around last quarter moon.
Why two high and two low tides each day?
If the moon is primarily responsible for the tides, why are there two high tides and two low tides each day in most places? It seems as if there should just be one. If you picture the part of Earth closest to the moon, it’s easy to see that the ocean is drawn toward the moon. That’s because gravity depends in part on how close two objects are.
But then why – on the opposite side of Earth – is there another tidal bulge, in the direction opposite the moon? It seems counterintuitive, until you realize that this second bulge happens at the part of Earth where the moon’s gravity is pulling the least.
Earth spins once every 24 hours. So, a given location on Earth will pass “through” both bulges of water each day. Of course, the bulges don’t stay fixed in time. They move at the slow rate of about 13.1 degrees per day. That’s the same rate as the monthly motion of the moon relative to the stars. Other factors, including the shape of coastlines, also influence the time of the tides. That’s why people who live near coastlines like to have a good tide almanac.
Bottom line: The sun, the moon, the shape of a beach, the angle of the seabed leading up to land and the prevailing ocean currents and winds all affect the height of the tides. Expect higher-than-usual tides for a few days following the full supermoon, on December 4.
View at EarthSky Community Photos. | Cecille Kennedy captured these crashing ocean waves in Oregon on December 14, 2024, the day of a full moon. Cecille wrote: “It is the time of king tides at the Oregon coast. The tides get higher than other times of the year when the sun, moon and Earth are in alignment.” Thank you, Cecille!
Today – December 4, 2025 – is the full Cold Moon. Full moons occur when the Earth, moon and sun are most aligned in space, with the moon opposite the sun and the Earth in the middle. The full Cold Moon will fall at 23:14 UTC today and it’s a supermoon. And that’s just a little over 12 hours after the moon reaches perigee, its closest point to Earth for this month. So, today’s moon is a full supermoon, and the 2nd closest full moon of 2025.
The full moon will rise tonight opposite the sunset. It will be highest in the sky around midnight and set opposite the sunrise tomorrow morning. And Earth’s oceans will feel the double whammy of the sun and moon.
Especially if you live along a coast, you might know that the highest tides – sometimes called perigean tides, or king tides or even supermoon tides – tend to fall on the day or so after a new or full supermoon. Watch for these high tides for a few days.
Around each new moon and full moon – when the sun, Earth and moon are located more or less on a line in space – the range between high and low tides is greatest. These are perigean tides, also known as king tides or supermoon tides. Image via NOAA/ National Ocean Service.
Supermoons in 2025
December’s full supermoon is the 3rd – and 2nd closest – of four full supermoons in a row. We’ll have one more full supermoon in January 2026.
And what about new supermoons? In 2025, we had five new supermoons in a row. They were in February, March, April, May and June. The new supermoon in March was the closest new moon of 2025.
What are spring tides?
In most places, but not everywhere, there are two high tides and two low tides a day. The difference in height between high and low tides varies, as the moon waxes and wanes from new to full and back to new again. The moon and sun are primarily responsible for the rising and falling of ocean tides. However, for any particular place on Earth’s surface, the height of the tides and their fluctuation in time also depend on the shape of your specific beach and the angle of the seabed leading up to your beach. Plus your larger coastline and the prevailing ocean currents and winds.
Around each new moon and full moon, the sun, Earth and moon lie more or less along a line in space. Then the pull on the tides increases, because the gravity of the sun reinforces the moon’s gravity. In fact, the height of the average solar tide is about 50% of the average lunar tide.
Thus, at new moon or full moon, the tide’s range is at its maximum. This is the spring tide: the highest (and lowest) tide. Spring tides are not named for the season. This is spring in the sense of jump, burst forth, rise.
So, spring tides bring the most extreme high and low tides every month. And they always happen – every month – around full and new moon.
Why?
When the new moon or full moon closely aligns with perigee – the closest point to Earth in the moon’s orbit – then we have a supermoon and extra-large spring tides.
In 2018, the January 1-2 full moon closely aligned with perigee to bring forth especially high tides. As it happened, on the day after the January 1-2 supermoon, Storm Eleanor hit Europe with winds of up to 100 mph (160 km/h). The wind and extra-high tides caused flooding, hampered travel, injured and killed people and left tens of thousands of homes without power across the U.K., Ireland and other parts of Europe. No doubt the extra-high tides contributed to the severity of the storm. Read more: High tides and winter storms (2018).
Why are the tides at their strongest around supermoons? It’s simply because the moon is at its closest to Earth, and thus the Earth’s oceans are feeling the pull of the moon’s gravity most powerfully.
Should you expect these highest tides on the exact day of a supermoon? Probably not. The highest tides tend to follow the supermoon (or any new or full moon) by a day or two.
What about flooding?
Do the most extreme high tides – those bringing floods – always occur at supermoons? Not necessarily. It’s when a spring tide coincides with a time of heavy winds and rain – flooding due to a weather extreme – that the most extreme flooding occurs.
Spring tides and neap tides coincide with particular phases of the moon. Around each new moon and full moon – when the sun, Earth, and moon align in space – the range between high and low tides is greatest. These are the spring tides. Around each first quarter moon and last quarter moon – when the sun and moon are at a right angle – the range between high and low tides is the least. These are the neap tides. Image via NOAA/ National Ocean Service.View at EarthSky Community Photos. | Christy Mandeville of Indian Shores, Florida, captured this image of ocean waves surging onto a beach on June 4, 2023. Thank you, Christy!
What are neap tides?
There’s about a seven-day interval between spring tides and neap tides, when the tide’s range is at its minimum. Neap tides occur halfway between each new and full moon – at the first quarter and last quarter moon phase – when the sun and moon are at right angles as seen from Earth. Then the sun’s gravity is working against the gravity of the moon, as the moon pulls on the sea. Neap tides happen approximately twice a month, once around first quarter moon and once around last quarter moon.
Why two high and two low tides each day?
If the moon is primarily responsible for the tides, why are there two high tides and two low tides each day in most places? It seems as if there should just be one. If you picture the part of Earth closest to the moon, it’s easy to see that the ocean is drawn toward the moon. That’s because gravity depends in part on how close two objects are.
But then why – on the opposite side of Earth – is there another tidal bulge, in the direction opposite the moon? It seems counterintuitive, until you realize that this second bulge happens at the part of Earth where the moon’s gravity is pulling the least.
Earth spins once every 24 hours. So, a given location on Earth will pass “through” both bulges of water each day. Of course, the bulges don’t stay fixed in time. They move at the slow rate of about 13.1 degrees per day. That’s the same rate as the monthly motion of the moon relative to the stars. Other factors, including the shape of coastlines, also influence the time of the tides. That’s why people who live near coastlines like to have a good tide almanac.
Bottom line: The sun, the moon, the shape of a beach, the angle of the seabed leading up to land and the prevailing ocean currents and winds all affect the height of the tides. Expect higher-than-usual tides for a few days following the full supermoon, on December 4.
View at EarthSky Community Photos. | Steven Bellavia captured Mercury’s sodium tail on the morning of December 3, 2025, from Surry, Virginia. Steven wrote: “A 24-million-km-long plume of gas is ejected from Mercury’s thin atmosphere due to the sun, very much like a comet. This phenomenon is only visible using a narrowband filter that captures the bright yellow sodium light at 589 nanometers (nm).” Thank you, Steven!
Mercury’s sodium tail is back! This beguiling phenomenon appears best when Mercury is closest to the sun, or at perihelion. The tail contains sodium atoms, so we can only see it with the help of special filters and long-exposure photographs. Steven Bellavia has now imaged Mercury’s sodium tail five times over the past several years. His latest capture was on Tuesday morning, December 3, 2025.
The long, flowing tail trailing away from Mercury is in the opposite direction of the sun, much like a comet. Scientists first predicted Mercury had a tail in the 1980s and discovered it in 2001. Also, NASA’s MESSENGER mission, which orbited Mercury between 2011 and 2015, revealed many details in the tail. Nowadays, astrophotographers here on Earth are able to capture great shots of Mercury’s tail with the right equipment and a little know-how. Here, Steven Bellavia shares his images and techniques for capturing this unusual phenomenon, below.
Why does Mercury have a tail?
The answer lies in part in sodium atoms. These atoms are freed from Mercury’s surface by the push of sunlight and micrometeorite impacts. The sodium atoms from the surface are blasted into Mercury’s atmosphere and into space, where they form the planet’s tail.
MESSENGER discovered that sunlight scatters off the sodium atoms, giving them a yellow or orange glow. The sun isn’t just selectively blowing sodium off the surface of Mercury, though. Indeed, Mercury’s tail is made up of many elements. But sodium gets the top billing because it does such a good job of scattering yellow light. This allows the tail to appear on long-exposure photographs.
And how big is Mercury’s sodium tail? It’s roughly 100 times longer than the diameter of Earth!
View at EarthSky Community Photos. | Steven Bellavia in Southold, New York, captured this photo on April 10, 2023. Steven wrote: “A plume of gas flowing from Mercury’s thin atmosphere. The sun causes Mercury’s sodium tail much like it does for a comet.” Thank you, Steven!
How to photograph Mercury’s tail
Mercury’s tail is brightest within 16 days of perihelion, the planet’s closest point to the sun. Mercury reaches perihelion every 88 days (it takes 88 days to orbit the sun once). In the photo at top, Steven Bellavia captured Mercury on December 3, 2025. And Mercury’s most recent perihelion was on November 23, 2025.
Bellavia told EarthSky that an article at Spaceweather.com on May 10, 2021, inspired him to try photographing Mercury’s sodium tail using a 589 nanometer (nm) wavelength filter that lets the sodium light signature through. After reading about it, he was eager to try it for himself. He explained:
On the morning of Wednesday, May 11, 2021, I ordered a 589 nm narrowband filter, with 10 nm of bandpass [the wavelength range of the filter], from Edmund Optics. A friend who owns a 3D printer printed me two rings that I designed to hold the filter, as the filter did not come with standard mounting used in astronomy. I used the new setup within hours of getting it all together.
Ingenious!
Bellavia’s 1st photos of Mercury’s sodium tail
Bellavia first captured photos of Mercury’s tail on both May 13 and 14, 2021. He used a tracking German equatorial mount affixed with a Canon 100mm lens and the filter mounted in front of the lens. On the first night he took 30 exposures of 30 seconds each, while on the second night he took 20 exposures of 60 seconds each using a Borg 90mm refractor. He said:
On the second night, having seen the results from my first attempt, I realized that it would be better to have the telescope and mount track on Mercury itself, as the tail is faint, and all photons collected need to land as frequently as possible on the same pixels in each individual image to reveal it. Also note that on both nights, I would have liked to have taken many more images, but I needed to wait for the background sky to be dark enough to reveal the tail. But Mercury was also setting at this time, either behind land or into clouds near the horizon.
Even with these limitations, however, Bellavia’s photos of Mercury’s sodium tail are remarkable.
Photos of Mercury’s tail
View at EarthSky Community Photos. | Steven Bellavia in New Suffolk, New York, took this photo of Mercury’s sodium tail on October 11, 2022. Steven wrote: “A 15-million-mile-long (24-million-km-long) plume of gas is ejected from Mercury’s thin atmosphere due to the sun, very much like a comet.” Thanks, Steven!Steven Bellavia captured this image on May 14, 2021. It gives us a closer look at Mercury’s tail. Bellavia took up the hobbies of astronomy and astrophotography at the age of 10 and has worked professionally on aerospace, physics and astronomy projects for most of his life.View at EarthSky Community Photos. | Steven Bellavia in Southold, New York, created this composite image of Mercury’s sodium tail on May 13, 2021. It consists of 30 stacked 30-second exposures of Mercury, combined with an image of that night’s crescent moon. Thanks, Steven!View at EarthSky Community Photos. | Steven Bellavia in Southold, New York, captured this photo on April 24, 2022. Steven said: “Only a narrowband filter that captures the bright yellow sodium light at 589 nanometers shows this sodium tail.” Thanks, Steven!
Sodium in the universe
Astronomers can use filters in the 589 nm range to learn about more objects than just Mercury’s tail. For example, the sun and comets are good targets for sodium filters. Astronomers have also seen sodium streaming from our moon, as well as surrounding Jupiter in a haze after being blown off its moon Io. In addition, discovery of sodium in other star systems allows scientists to learn about rocky exoplanets. They can even use sodium absorption bands to measure redshifts and the size of the universe.
This view of a 7-degree segment of sky through a sodium filter detects the long tail streaming behind Mercury and away from the sun. Image via University of California, Irvine.When NASA’s MESSENGER spacecraft flew past Mercury, it saw sodium flowing off the planet due to the solar wind, which shaped it into a tail streaming away from the planet in the opposite direction from the sun. That’s much like how a comet’s tail blown by the solar wind points away from the sun. Image via NASA.
Thank you, Steven Bellavia, for your help in assembling this information.
Bottom line: On December 3, 2025, Steven Bellavia imaged Mercury’s sodium tail flowing away from the sun. Mercury recently passed perihelion and will be farthest from the morning sun on December 7.
View at EarthSky Community Photos. | Steven Bellavia captured Mercury’s sodium tail on the morning of December 3, 2025, from Surry, Virginia. Steven wrote: “A 24-million-km-long plume of gas is ejected from Mercury’s thin atmosphere due to the sun, very much like a comet. This phenomenon is only visible using a narrowband filter that captures the bright yellow sodium light at 589 nanometers (nm).” Thank you, Steven!
Mercury’s sodium tail is back! This beguiling phenomenon appears best when Mercury is closest to the sun, or at perihelion. The tail contains sodium atoms, so we can only see it with the help of special filters and long-exposure photographs. Steven Bellavia has now imaged Mercury’s sodium tail five times over the past several years. His latest capture was on Tuesday morning, December 3, 2025.
The long, flowing tail trailing away from Mercury is in the opposite direction of the sun, much like a comet. Scientists first predicted Mercury had a tail in the 1980s and discovered it in 2001. Also, NASA’s MESSENGER mission, which orbited Mercury between 2011 and 2015, revealed many details in the tail. Nowadays, astrophotographers here on Earth are able to capture great shots of Mercury’s tail with the right equipment and a little know-how. Here, Steven Bellavia shares his images and techniques for capturing this unusual phenomenon, below.
Why does Mercury have a tail?
The answer lies in part in sodium atoms. These atoms are freed from Mercury’s surface by the push of sunlight and micrometeorite impacts. The sodium atoms from the surface are blasted into Mercury’s atmosphere and into space, where they form the planet’s tail.
MESSENGER discovered that sunlight scatters off the sodium atoms, giving them a yellow or orange glow. The sun isn’t just selectively blowing sodium off the surface of Mercury, though. Indeed, Mercury’s tail is made up of many elements. But sodium gets the top billing because it does such a good job of scattering yellow light. This allows the tail to appear on long-exposure photographs.
And how big is Mercury’s sodium tail? It’s roughly 100 times longer than the diameter of Earth!
View at EarthSky Community Photos. | Steven Bellavia in Southold, New York, captured this photo on April 10, 2023. Steven wrote: “A plume of gas flowing from Mercury’s thin atmosphere. The sun causes Mercury’s sodium tail much like it does for a comet.” Thank you, Steven!
How to photograph Mercury’s tail
Mercury’s tail is brightest within 16 days of perihelion, the planet’s closest point to the sun. Mercury reaches perihelion every 88 days (it takes 88 days to orbit the sun once). In the photo at top, Steven Bellavia captured Mercury on December 3, 2025. And Mercury’s most recent perihelion was on November 23, 2025.
Bellavia told EarthSky that an article at Spaceweather.com on May 10, 2021, inspired him to try photographing Mercury’s sodium tail using a 589 nanometer (nm) wavelength filter that lets the sodium light signature through. After reading about it, he was eager to try it for himself. He explained:
On the morning of Wednesday, May 11, 2021, I ordered a 589 nm narrowband filter, with 10 nm of bandpass [the wavelength range of the filter], from Edmund Optics. A friend who owns a 3D printer printed me two rings that I designed to hold the filter, as the filter did not come with standard mounting used in astronomy. I used the new setup within hours of getting it all together.
Ingenious!
Bellavia’s 1st photos of Mercury’s sodium tail
Bellavia first captured photos of Mercury’s tail on both May 13 and 14, 2021. He used a tracking German equatorial mount affixed with a Canon 100mm lens and the filter mounted in front of the lens. On the first night he took 30 exposures of 30 seconds each, while on the second night he took 20 exposures of 60 seconds each using a Borg 90mm refractor. He said:
On the second night, having seen the results from my first attempt, I realized that it would be better to have the telescope and mount track on Mercury itself, as the tail is faint, and all photons collected need to land as frequently as possible on the same pixels in each individual image to reveal it. Also note that on both nights, I would have liked to have taken many more images, but I needed to wait for the background sky to be dark enough to reveal the tail. But Mercury was also setting at this time, either behind land or into clouds near the horizon.
Even with these limitations, however, Bellavia’s photos of Mercury’s sodium tail are remarkable.
Photos of Mercury’s tail
View at EarthSky Community Photos. | Steven Bellavia in New Suffolk, New York, took this photo of Mercury’s sodium tail on October 11, 2022. Steven wrote: “A 15-million-mile-long (24-million-km-long) plume of gas is ejected from Mercury’s thin atmosphere due to the sun, very much like a comet.” Thanks, Steven!Steven Bellavia captured this image on May 14, 2021. It gives us a closer look at Mercury’s tail. Bellavia took up the hobbies of astronomy and astrophotography at the age of 10 and has worked professionally on aerospace, physics and astronomy projects for most of his life.View at EarthSky Community Photos. | Steven Bellavia in Southold, New York, created this composite image of Mercury’s sodium tail on May 13, 2021. It consists of 30 stacked 30-second exposures of Mercury, combined with an image of that night’s crescent moon. Thanks, Steven!View at EarthSky Community Photos. | Steven Bellavia in Southold, New York, captured this photo on April 24, 2022. Steven said: “Only a narrowband filter that captures the bright yellow sodium light at 589 nanometers shows this sodium tail.” Thanks, Steven!
Sodium in the universe
Astronomers can use filters in the 589 nm range to learn about more objects than just Mercury’s tail. For example, the sun and comets are good targets for sodium filters. Astronomers have also seen sodium streaming from our moon, as well as surrounding Jupiter in a haze after being blown off its moon Io. In addition, discovery of sodium in other star systems allows scientists to learn about rocky exoplanets. They can even use sodium absorption bands to measure redshifts and the size of the universe.
This view of a 7-degree segment of sky through a sodium filter detects the long tail streaming behind Mercury and away from the sun. Image via University of California, Irvine.When NASA’s MESSENGER spacecraft flew past Mercury, it saw sodium flowing off the planet due to the solar wind, which shaped it into a tail streaming away from the planet in the opposite direction from the sun. That’s much like how a comet’s tail blown by the solar wind points away from the sun. Image via NASA.
Thank you, Steven Bellavia, for your help in assembling this information.
Bottom line: On December 3, 2025, Steven Bellavia imaged Mercury’s sodium tail flowing away from the sun. Mercury recently passed perihelion and will be farthest from the morning sun on December 7.
We’ve all seen a full moon looming large shortly after it rises, when it’s still hugging the horizon. And it’s true that the moon is sometimes closer to Earth than at other times, making it minutely larger in our sky. Yet the difference is barely discernible. When the moon viewed near the horizon looks larger than usual, your brain is playing a trick on you. It’s called the moon illusion.
You can check it out tonight, on the full Cold Moon. It’ll be the second closest moon – or supermoon – of 2025. And this larger than normal moon will look huge – and bright – near the horizon.
We still don’t know the precise cause of the moon illusion. But the video above, from AsapSCIENCE, offers some explanations.
A common theory is when the moon is near the horizon, you’re seeing it in the company of many familiar visual reference points: trees, buildings, mountains and so on. Your brain automatically compares the moon to these reference points. But when the moon is higher up, there’s nothing to compare it to. As AsapSCIENCE says:
The moon seems smaller against the vastness of the night sky.
The moon looks bigger on the horizon. There is an optical illusion which makes the moon appear to be larger the lower it is in the sky. pic.twitter.com/zMAiAJ58g7
Maybe you’d like to test this theory yourself. According to NASA, here are some ways to prove it to yourself:
Hold up your outstretched index finger next to the moon. You’ll find that your fingernail and the moon are about the same size. Or try looking at the moon through a paper tube, or bend over and look backward between your legs. When you view it like this, the moon will be nowhere near as big as it had seemed.
Or NASA suggests:
Another ironclad way to size-check the moon is to take a photo when it’s near the horizon, and another when it’s high in the sky. If you keep your camera zoom settings the same, you’ll find that the moon is the same width, side to side, in both photos.
What about a red or orange moon?
By the way, there’s a second phenomenon that the moon displays when we see it near the horizon. That is, a low moon often appears red or orange in color. That reddish color is not an illusion. It’s a true physical effect, caused by the fact that – when the moon is low in the sky – you’re seeing it through a greater thickness of Earth’s atmosphere than when it’s overhead. The atmosphere filters out the bluer wavelengths of moonlight (which is really reflected sunlight). Meanwhile, it allows the red component of moonlight to travel straight through to your eyes. So a low moon is likely to look red or orange to you.
So how do people get those photos of extra big moons seen near a horizon? Photographers use zoom lenses and have familiar objects in the foreground making the more distant moon look huge. So they’re the result of photographic tricks and techniques, which you can read about here or here.
View at EarthSky Community Photos. | A great example of the moon illusion from Stephanie Becker in Soda Springs, California. She captured this image of the July full supermoon on July 2, 2023. Thank you, Stephanie!View at EarthSky Community Photos. | Cecille Kennedy in Depoe Bay, Oregon, captured this image on August 30, 2023. Cecille wrote: “The blue supermoon shines behind the clouds as it rises over the hills and the trees. A few minutes before the moon rose, the clouds were lavender rose pink. Then the lovely moon appeared.” Thank you, Cecille!
If you get a great photo of the full Cold Moon supermoon, you can submit it here. We would love to see it!
Bottom line: It’s the full Cold Moon tonight. And it’s a supermoon. You might see a large-looking moon low in the sky. It’s the moon illusion that makes the moon look so big.
We’ve all seen a full moon looming large shortly after it rises, when it’s still hugging the horizon. And it’s true that the moon is sometimes closer to Earth than at other times, making it minutely larger in our sky. Yet the difference is barely discernible. When the moon viewed near the horizon looks larger than usual, your brain is playing a trick on you. It’s called the moon illusion.
You can check it out tonight, on the full Cold Moon. It’ll be the second closest moon – or supermoon – of 2025. And this larger than normal moon will look huge – and bright – near the horizon.
We still don’t know the precise cause of the moon illusion. But the video above, from AsapSCIENCE, offers some explanations.
A common theory is when the moon is near the horizon, you’re seeing it in the company of many familiar visual reference points: trees, buildings, mountains and so on. Your brain automatically compares the moon to these reference points. But when the moon is higher up, there’s nothing to compare it to. As AsapSCIENCE says:
The moon seems smaller against the vastness of the night sky.
The moon looks bigger on the horizon. There is an optical illusion which makes the moon appear to be larger the lower it is in the sky. pic.twitter.com/zMAiAJ58g7
Maybe you’d like to test this theory yourself. According to NASA, here are some ways to prove it to yourself:
Hold up your outstretched index finger next to the moon. You’ll find that your fingernail and the moon are about the same size. Or try looking at the moon through a paper tube, or bend over and look backward between your legs. When you view it like this, the moon will be nowhere near as big as it had seemed.
Or NASA suggests:
Another ironclad way to size-check the moon is to take a photo when it’s near the horizon, and another when it’s high in the sky. If you keep your camera zoom settings the same, you’ll find that the moon is the same width, side to side, in both photos.
What about a red or orange moon?
By the way, there’s a second phenomenon that the moon displays when we see it near the horizon. That is, a low moon often appears red or orange in color. That reddish color is not an illusion. It’s a true physical effect, caused by the fact that – when the moon is low in the sky – you’re seeing it through a greater thickness of Earth’s atmosphere than when it’s overhead. The atmosphere filters out the bluer wavelengths of moonlight (which is really reflected sunlight). Meanwhile, it allows the red component of moonlight to travel straight through to your eyes. So a low moon is likely to look red or orange to you.
So how do people get those photos of extra big moons seen near a horizon? Photographers use zoom lenses and have familiar objects in the foreground making the more distant moon look huge. So they’re the result of photographic tricks and techniques, which you can read about here or here.
View at EarthSky Community Photos. | A great example of the moon illusion from Stephanie Becker in Soda Springs, California. She captured this image of the July full supermoon on July 2, 2023. Thank you, Stephanie!View at EarthSky Community Photos. | Cecille Kennedy in Depoe Bay, Oregon, captured this image on August 30, 2023. Cecille wrote: “The blue supermoon shines behind the clouds as it rises over the hills and the trees. A few minutes before the moon rose, the clouds were lavender rose pink. Then the lovely moon appeared.” Thank you, Cecille!
If you get a great photo of the full Cold Moon supermoon, you can submit it here. We would love to see it!
Bottom line: It’s the full Cold Moon tonight. And it’s a supermoon. You might see a large-looking moon low in the sky. It’s the moon illusion that makes the moon look so big.
A December birthstone, turquoise, from Nishapur in northeastern Iran. Image via Sonia Sevilla/ Wikimedia Commons (CC0 1.0).
If you were born in December, you have a choice of three birthstones: turquoise, zircon or tanzanite. Turquoise, a soft gemstone used in jewelry and ornaments, has a rich history dating to antiquity. Zircons are not well-known gemstones, but they make absolutely stunning jewelry. Tanzanite is an exquisite clear blue-violet crystal found only in Tanzania.
Why do some months have one birthstone but others have two or three? According to the website onecklace.com, multiple stones for some months allow more affordable options in addition to the traditional and more expensive stones.
To chemists and geologists, turquoise is copper aluminum phosphate. It forms when rainwater or melted snow percolates through copper ore deposits called copper porphyry. Water interacts with copper sulfides in the ore to form an acidic solution. This copper-carrying acidic water, when it reacts with aluminum and potassium in the rocks, precipitates turquoise into cavities. You can find turquoise in weathered volcanic rock and sedimentary rock in arid locations.
Turquoise is a relatively soft gemstone, with a Mohs scale hardness of five to six. You can scratch or break turquoise with moderate force. Oil and pigments easily discolor this porous opaque stone. It also changes color when it loses some of its water content.
Hard, relatively non-porous, compact stones have the best appearance because the stone can be finely polished. “Softer” varieties that are more porous are treated with oil, paraffin, liquid plastic or water glass to enhance durability and color.
Copper gives a sky-blue shade to turquoise, while iron gives it a greener tone. The most valued variety of turquoise is an intense sky-blue color, like the color of a robin’s egg. Ochre and brown-black veins, often found in the gemstones, are inclusions from the surrounding rock matrix.
Turquoise facts
Some of the best turquoise in the world comes from Iran, famous for its sky-blue stones from Neyshabur. In Egypt, people have mined turquoise in the Sinai Peninsula for over 5,000 years. Turquoise is found in many U.S. southwestern states: Arizona, California, Colorado, New Mexico and Nevada. This stone also occurs in Afghanistan, Australia, China, India, Tibet, Mexico and Brazil.
Turquoise from Cerillos, New Mexico, part of a collection at the Smithsonian Museum of Natural History. Image via Tim Evanson/ Wikimedia Commons (CC BY-SA 2.0).
The word turquoiseoriginated from the French phrase pierre turquoise, meaning Turkish stone. That’s because Venetian traders brought the gemstone to Europe after acquiring it from traders in Turkey.
In antiquity, turquoise was used as jewelry by the ruling classes of civilizations in Africa, Asia and the Americas. People have found beads dating to the late 6th millennium BCE in ancient Iraq. Turquoise bracelets were on the arm of a woman in the tomb of Zer, a pharaoh who ruled Egypt around 3000 BCE. A 3,700-year-old dragon relic from the Xia Dynasty, made from over 2,000 pieces of turquoise, was in the tomb of a nobleman in central China.
Turquoise in the Americas
Turquoise has a rich history in the American Southwest. Native Americans have been using this gemstone to create jewelry and ornamental pieces for several thousand years. The Apache, Navajo, Pueblo, and Zuni tribes are known for their turquoise jewelry.
In the Zuni language, the word for turquoise means sky stone. During the growing season in summer, Pueblo dancers wear turquoise to encourage rainfall. The Navajo people associate turquoise with health and protection, using the stone in important rites of passage. Interestingly, the Apache people believed that turquoise lay at the end of a rainbow, and that turquoise attached to a bow or gun ensured an accurate aim.
Turquoise was a part of pre-Columbian cultures in Mexico, Central America, and South America. In Peru, prehistoric tribes made small objects such as beads, figurines and artifacts with turquoise inlays. For the Aztecs, turquoise was popular in ornaments. It also had important religious and ceremonial uses. For example, a high priest involved in human sacrifice wore a turquoise pendant hung from his underlip. A notable Aztec art form was intricate turquoise mosaics, like that of a turquoise mosaic mask used in the interment of a king.
Turquoise lore
Some people consider turquoise a love charm. When received as a gift, it is supposed to symbolize a pledge of affection. Shakespeare used this lore in “The Merchant of Venice.” In it, Leah gave a turquoise ring to Shylock when he was a bachelor, hoping it would win his affections so he would ask her to marry him.
There are many other superstitions associated with turquoise. In the twelfth century, an Arabian writing declared:
… the turquoise shines when the air is pure and becomes pale when it is dim.
They also believed that its color changed with the weather. In the 13th century, people believed it would protect its owner from injury if he fell off a horse.
George Frederick Kunz’s book, The Curious Lore of Precious Stones, stated that diamonds and turquoises supposedly lost their powers if sold:
The spirit dwelling in the stone was thought to take offence at the idea of being bought and sold, and was supposed to depart from the stone, leaving it nothing more than a bit of senseless matter. If, however, the diamond (or turquoise) were offered as a pledge of love or friendship, the spirit was quite willing to transfer its good offices from one owner to another.
There were also health myths associated with turquoise. People believed the stone changed color when its wearer became ill. Some said it was an effective treatment for scorpion stings and pain from evil influences. Just looking at turquoise supposedly strengthen the eyes.
December birthstone: zircon
Several red zircon crystals embedded in a mostly quartz matrix. The entire piece measures about 2.1 cm (0.8 inches) in diameter. Image via Robert M. Lavinsky/ Wikimedia Commons (CC BY-SA 3.0).
Zircon is a mineral formed of the elements zirconium and silicon (zirconium silicate). Most igneous rocks contain small crystals, just a few millimeters in size. With a Mohs scale hardness of 7.5, zircon is hard enough to survive the geologic forces that create metamorphic and sedimentary rock. But large zircon crystals are rare. They’re formed mainly in pegmatites (coarse-grained igneous rock) and carbonatites. But due to weathering of gem-bearing rocks, most zircons are in alluvial and beach deposits.
The name zircon may have come from the Arabic words zarquin, meaning red. Alternatively, it might have derived from the Persian word zargus, meaning gold-colored.
Major sources of gemstone-quality zircon are Thailand, Cambodia, Vietnam and Sri Lanka. The gemstones also occur in Myanmar, France, Norway, Australia and Canada.
Colors of zircon
Over vast spans of geologic time, forces have worked within zirconium silicate crystals to change their molecular structure and color. Uranium and thorium inclusions emit radiation that alters the original crystal structure. A glass-like material forms, with colors of red to brown, orange and yellow. Green is the rarest of the natural colors. Since the 1920s, most gemstones have undergone heat treatment to bring out their colors. This produces colorless zircons, as well as blue and golden stones.
The creation of blue stones is in an interesting story relayed in “Gems and Crystals” by Anna S. Sofianides and George E. Harlow:
In the 1920s, a new blue gemstone suddenly appeared in the market. Endowed with spectacular brilliance, it was an immediate hit.
The creation of the blue zircon
The gems, it turned out, were zircons, normally brown to green, but never before blue. George F. Kunz, the legendary Tiffany gemologist, immediately suspected trickery. Not only were there extraordinary stones available in abundance, but they were available all over the world! Upon Kunz’s behest, a colleague made inquiries during a trip to Siam (Thailand) and learned that a large deposit of unattractive brown zircon had stimulated color-improvement experimentation by local entrepreneurs. Heating in an oxygen-free environment made the drab material into “new” blue stones, which vendors sent to outlets worldwide. Even after finding out about the deception, the market simply accepted the information and the demand for the new gems continued unabated.
The blue stones are a clear favorite among zircon customers. Red and green colors are also valuable. Colorless zircons are excellent imitators of diamonds, in appearance only, with a brilliant fire almost as dazzling as the real thing. However, zircon can be brittle and cutting takes great care. It breaks with a well-placed knock, due to internal stresses in the crystal caused by radiation damage and heat treatment. But it remains in demand for its stunning beauty. In addition, other factors that affect pricing of the gemstones are clarity and an absence of visible inclusions.
Zircon lore
Green zircon was among the stones of the Kalpa Tree of the Hindu religion, where it represented the tree’s foliage. This tree was a symbolic offering to the gods. Hindu poets of the 19th century described it as part of a glowing ensemble of precious stones that also included sapphires, diamonds and topaz.
The hyacinth and jacinth, reddish-brown and orange-red varieties of zircon, were a favorite stone of ancient Arabs, even mentioned in the famed “Arabian Nights.”
During the 14th century, zircon was popular as a safeguard against the Black Death, the great plague that wiped out a quarter of the population of Europe. People believed the stone possessed healing powers: to induce sleep, as an antidote against poison, and as an aid to digestion.
A rare olive-green zircon, measuring about 3.4 cm (1.3 inches) in length, from Myanmar. Image via Robert M. Lavinsky/ Wikimedia Commons (CC BY-SA 3.0).
December birthstone: tanzanite
A tanzanite crystal from the Merelani Hills, Arusha Region, Tanzania. Image via Parent Géry/ Wikimedia Commons (CC BY-SA 3.0).
Tanzanite is an unusual form of the mineral zoisite (calcium aluminium hydroxyl sorosilicate). Its colors, blue and violet, are due to the presence of vanadium in the zoisite crystals. This gemstone formed 585 million years ago under extreme heat during intense plate tectonic activity, in a place that would someday become Mount Kilimanjaro in northern Tanzania.
Today, you can only find tanzanite in the Merelani Hills near the foot of Mount Kilimanjaro.
Colors from different angles
In its natural form, tanzanite appears brown, yellowish green, blue and violet, flashing these colors when viewed from different angles. This phenomenon is pleochroism, where you can see different colors depending on how light hits the gemstone.
The type of lighting can also make a difference. Under fluorescent lights, tanzanite appears bluer, while under incandescent light, more violet hues emerge.
However, most crystals used in jewelry received doses of heat to remove the brownish color found in the natural tanzanite. The results are more intensely blue and violet gems. On rare occasions, heated stones can produce a green gem with secondary blue and violet colors. For cut gems, cutters can influence their overall color by how they craft the gem.
Tanzanite’s recent history
While most birthstones have histories spanning hundreds and even thousands of years, tanzanite’s story began in 1967. A Masai tribesman found unusual clear violet-blue crystals in the Merelani Hills in northern Tanzania. He notified a local tailor and prospector, Manuel d’Souza, who, upon finding the gemstones, filed the first of many mining claims.
Initially, d’Souza thought they were sapphires. But no one knew for sure. The stones made their way to geologists at the Gemological Institute of America where they identified them as an unusual form of zoisite.
And then, the famed jewelry purveyors, Tiffany & Company, took an interest in the gem. In 1968, they began a marketing campaign. To make the gems more appealing to buyers, they renamed blue zoisite to tanzanite, in honor of its country of origin. Finally, in 2002, the American Gem Trade Association selected tanzanite to join turquoise and zircon as December birthstones.
Beyond the December birthstone: birthstones for all months
Bottom line: December babies are fortunate enough to have three choices for their birthstone. Turquoise, zircon and tanzanite are the birthstones for December.
A December birthstone, turquoise, from Nishapur in northeastern Iran. Image via Sonia Sevilla/ Wikimedia Commons (CC0 1.0).
If you were born in December, you have a choice of three birthstones: turquoise, zircon or tanzanite. Turquoise, a soft gemstone used in jewelry and ornaments, has a rich history dating to antiquity. Zircons are not well-known gemstones, but they make absolutely stunning jewelry. Tanzanite is an exquisite clear blue-violet crystal found only in Tanzania.
Why do some months have one birthstone but others have two or three? According to the website onecklace.com, multiple stones for some months allow more affordable options in addition to the traditional and more expensive stones.
To chemists and geologists, turquoise is copper aluminum phosphate. It forms when rainwater or melted snow percolates through copper ore deposits called copper porphyry. Water interacts with copper sulfides in the ore to form an acidic solution. This copper-carrying acidic water, when it reacts with aluminum and potassium in the rocks, precipitates turquoise into cavities. You can find turquoise in weathered volcanic rock and sedimentary rock in arid locations.
Turquoise is a relatively soft gemstone, with a Mohs scale hardness of five to six. You can scratch or break turquoise with moderate force. Oil and pigments easily discolor this porous opaque stone. It also changes color when it loses some of its water content.
Hard, relatively non-porous, compact stones have the best appearance because the stone can be finely polished. “Softer” varieties that are more porous are treated with oil, paraffin, liquid plastic or water glass to enhance durability and color.
Copper gives a sky-blue shade to turquoise, while iron gives it a greener tone. The most valued variety of turquoise is an intense sky-blue color, like the color of a robin’s egg. Ochre and brown-black veins, often found in the gemstones, are inclusions from the surrounding rock matrix.
Turquoise facts
Some of the best turquoise in the world comes from Iran, famous for its sky-blue stones from Neyshabur. In Egypt, people have mined turquoise in the Sinai Peninsula for over 5,000 years. Turquoise is found in many U.S. southwestern states: Arizona, California, Colorado, New Mexico and Nevada. This stone also occurs in Afghanistan, Australia, China, India, Tibet, Mexico and Brazil.
Turquoise from Cerillos, New Mexico, part of a collection at the Smithsonian Museum of Natural History. Image via Tim Evanson/ Wikimedia Commons (CC BY-SA 2.0).
The word turquoiseoriginated from the French phrase pierre turquoise, meaning Turkish stone. That’s because Venetian traders brought the gemstone to Europe after acquiring it from traders in Turkey.
In antiquity, turquoise was used as jewelry by the ruling classes of civilizations in Africa, Asia and the Americas. People have found beads dating to the late 6th millennium BCE in ancient Iraq. Turquoise bracelets were on the arm of a woman in the tomb of Zer, a pharaoh who ruled Egypt around 3000 BCE. A 3,700-year-old dragon relic from the Xia Dynasty, made from over 2,000 pieces of turquoise, was in the tomb of a nobleman in central China.
Turquoise in the Americas
Turquoise has a rich history in the American Southwest. Native Americans have been using this gemstone to create jewelry and ornamental pieces for several thousand years. The Apache, Navajo, Pueblo, and Zuni tribes are known for their turquoise jewelry.
In the Zuni language, the word for turquoise means sky stone. During the growing season in summer, Pueblo dancers wear turquoise to encourage rainfall. The Navajo people associate turquoise with health and protection, using the stone in important rites of passage. Interestingly, the Apache people believed that turquoise lay at the end of a rainbow, and that turquoise attached to a bow or gun ensured an accurate aim.
Turquoise was a part of pre-Columbian cultures in Mexico, Central America, and South America. In Peru, prehistoric tribes made small objects such as beads, figurines and artifacts with turquoise inlays. For the Aztecs, turquoise was popular in ornaments. It also had important religious and ceremonial uses. For example, a high priest involved in human sacrifice wore a turquoise pendant hung from his underlip. A notable Aztec art form was intricate turquoise mosaics, like that of a turquoise mosaic mask used in the interment of a king.
Turquoise lore
Some people consider turquoise a love charm. When received as a gift, it is supposed to symbolize a pledge of affection. Shakespeare used this lore in “The Merchant of Venice.” In it, Leah gave a turquoise ring to Shylock when he was a bachelor, hoping it would win his affections so he would ask her to marry him.
There are many other superstitions associated with turquoise. In the twelfth century, an Arabian writing declared:
… the turquoise shines when the air is pure and becomes pale when it is dim.
They also believed that its color changed with the weather. In the 13th century, people believed it would protect its owner from injury if he fell off a horse.
George Frederick Kunz’s book, The Curious Lore of Precious Stones, stated that diamonds and turquoises supposedly lost their powers if sold:
The spirit dwelling in the stone was thought to take offence at the idea of being bought and sold, and was supposed to depart from the stone, leaving it nothing more than a bit of senseless matter. If, however, the diamond (or turquoise) were offered as a pledge of love or friendship, the spirit was quite willing to transfer its good offices from one owner to another.
There were also health myths associated with turquoise. People believed the stone changed color when its wearer became ill. Some said it was an effective treatment for scorpion stings and pain from evil influences. Just looking at turquoise supposedly strengthen the eyes.
December birthstone: zircon
Several red zircon crystals embedded in a mostly quartz matrix. The entire piece measures about 2.1 cm (0.8 inches) in diameter. Image via Robert M. Lavinsky/ Wikimedia Commons (CC BY-SA 3.0).
Zircon is a mineral formed of the elements zirconium and silicon (zirconium silicate). Most igneous rocks contain small crystals, just a few millimeters in size. With a Mohs scale hardness of 7.5, zircon is hard enough to survive the geologic forces that create metamorphic and sedimentary rock. But large zircon crystals are rare. They’re formed mainly in pegmatites (coarse-grained igneous rock) and carbonatites. But due to weathering of gem-bearing rocks, most zircons are in alluvial and beach deposits.
The name zircon may have come from the Arabic words zarquin, meaning red. Alternatively, it might have derived from the Persian word zargus, meaning gold-colored.
Major sources of gemstone-quality zircon are Thailand, Cambodia, Vietnam and Sri Lanka. The gemstones also occur in Myanmar, France, Norway, Australia and Canada.
Colors of zircon
Over vast spans of geologic time, forces have worked within zirconium silicate crystals to change their molecular structure and color. Uranium and thorium inclusions emit radiation that alters the original crystal structure. A glass-like material forms, with colors of red to brown, orange and yellow. Green is the rarest of the natural colors. Since the 1920s, most gemstones have undergone heat treatment to bring out their colors. This produces colorless zircons, as well as blue and golden stones.
The creation of blue stones is in an interesting story relayed in “Gems and Crystals” by Anna S. Sofianides and George E. Harlow:
In the 1920s, a new blue gemstone suddenly appeared in the market. Endowed with spectacular brilliance, it was an immediate hit.
The creation of the blue zircon
The gems, it turned out, were zircons, normally brown to green, but never before blue. George F. Kunz, the legendary Tiffany gemologist, immediately suspected trickery. Not only were there extraordinary stones available in abundance, but they were available all over the world! Upon Kunz’s behest, a colleague made inquiries during a trip to Siam (Thailand) and learned that a large deposit of unattractive brown zircon had stimulated color-improvement experimentation by local entrepreneurs. Heating in an oxygen-free environment made the drab material into “new” blue stones, which vendors sent to outlets worldwide. Even after finding out about the deception, the market simply accepted the information and the demand for the new gems continued unabated.
The blue stones are a clear favorite among zircon customers. Red and green colors are also valuable. Colorless zircons are excellent imitators of diamonds, in appearance only, with a brilliant fire almost as dazzling as the real thing. However, zircon can be brittle and cutting takes great care. It breaks with a well-placed knock, due to internal stresses in the crystal caused by radiation damage and heat treatment. But it remains in demand for its stunning beauty. In addition, other factors that affect pricing of the gemstones are clarity and an absence of visible inclusions.
Zircon lore
Green zircon was among the stones of the Kalpa Tree of the Hindu religion, where it represented the tree’s foliage. This tree was a symbolic offering to the gods. Hindu poets of the 19th century described it as part of a glowing ensemble of precious stones that also included sapphires, diamonds and topaz.
The hyacinth and jacinth, reddish-brown and orange-red varieties of zircon, were a favorite stone of ancient Arabs, even mentioned in the famed “Arabian Nights.”
During the 14th century, zircon was popular as a safeguard against the Black Death, the great plague that wiped out a quarter of the population of Europe. People believed the stone possessed healing powers: to induce sleep, as an antidote against poison, and as an aid to digestion.
A rare olive-green zircon, measuring about 3.4 cm (1.3 inches) in length, from Myanmar. Image via Robert M. Lavinsky/ Wikimedia Commons (CC BY-SA 3.0).
December birthstone: tanzanite
A tanzanite crystal from the Merelani Hills, Arusha Region, Tanzania. Image via Parent Géry/ Wikimedia Commons (CC BY-SA 3.0).
Tanzanite is an unusual form of the mineral zoisite (calcium aluminium hydroxyl sorosilicate). Its colors, blue and violet, are due to the presence of vanadium in the zoisite crystals. This gemstone formed 585 million years ago under extreme heat during intense plate tectonic activity, in a place that would someday become Mount Kilimanjaro in northern Tanzania.
Today, you can only find tanzanite in the Merelani Hills near the foot of Mount Kilimanjaro.
Colors from different angles
In its natural form, tanzanite appears brown, yellowish green, blue and violet, flashing these colors when viewed from different angles. This phenomenon is pleochroism, where you can see different colors depending on how light hits the gemstone.
The type of lighting can also make a difference. Under fluorescent lights, tanzanite appears bluer, while under incandescent light, more violet hues emerge.
However, most crystals used in jewelry received doses of heat to remove the brownish color found in the natural tanzanite. The results are more intensely blue and violet gems. On rare occasions, heated stones can produce a green gem with secondary blue and violet colors. For cut gems, cutters can influence their overall color by how they craft the gem.
Tanzanite’s recent history
While most birthstones have histories spanning hundreds and even thousands of years, tanzanite’s story began in 1967. A Masai tribesman found unusual clear violet-blue crystals in the Merelani Hills in northern Tanzania. He notified a local tailor and prospector, Manuel d’Souza, who, upon finding the gemstones, filed the first of many mining claims.
Initially, d’Souza thought they were sapphires. But no one knew for sure. The stones made their way to geologists at the Gemological Institute of America where they identified them as an unusual form of zoisite.
And then, the famed jewelry purveyors, Tiffany & Company, took an interest in the gem. In 1968, they began a marketing campaign. To make the gems more appealing to buyers, they renamed blue zoisite to tanzanite, in honor of its country of origin. Finally, in 2002, the American Gem Trade Association selected tanzanite to join turquoise and zircon as December birthstones.
Beyond the December birthstone: birthstones for all months
Bottom line: December babies are fortunate enough to have three choices for their birthstone. Turquoise, zircon and tanzanite are the birthstones for December.
