View at EarthSky Community Photos. | Patricia Evans in Seabrook, New Hampshire, captured these 3 moments from the Super Harvest Moon partial eclipse on September 17, 2024. Thank you, Patricia! See more Super Harvest Moon and eclipse pics below.
Super Harvest Moon and a partial lunar eclipse
People around the world were gazing at the Super Harvest Moon on September 17, 2024. And half of Earth also got to see the full moon in a partial eclipse. There won’t be another eclipse of a supermoon until October 8, 2033. If you missed Tuesday’s eclipse, you can enjoy the highlights here with photos from our EarthSky community. Have a great photo of your own to share? Submit it to us!
The morning of the Super Harvest Moon with Saturn
View at EarthSky Community Photos. | On the morning of the Harvest Moon, Joel Weatherly in Edmonton, Alberta, Canada, caught “Saturn moments away from disappearing behind the limb of the moon.” Stunning! Thank you, Joel!
View at EarthSky Community Photos. | Carol Kuehn was “looking across Keuka Lake at the hilltop on the western horizon” in New York when she caught the setting Harvest Moon on the morning of September 18, 2024. Thank you, Carol!View at EarthSky Community Photos. | Nicole Wascoe Bauman caught the setting Harvest Moon on the morning of September 18, 2024, from Albuquerque, New Mexico. Nicole wrote: “After a long night lighting up the sky, the Harvest Supermoon has one last hurrah in the western sky over Mt. Taylor.” Thanks, Nicole!
Bottom line: The Super Harvest Moon on September 17, 2024, was briefly darkened by Earth’s shadow in a partial lunar eclipse. Check out some great photos of the event here!
View at EarthSky Community Photos. | Patricia Evans in Seabrook, New Hampshire, captured these 3 moments from the Super Harvest Moon partial eclipse on September 17, 2024. Thank you, Patricia! See more Super Harvest Moon and eclipse pics below.
Super Harvest Moon and a partial lunar eclipse
People around the world were gazing at the Super Harvest Moon on September 17, 2024. And half of Earth also got to see the full moon in a partial eclipse. There won’t be another eclipse of a supermoon until October 8, 2033. If you missed Tuesday’s eclipse, you can enjoy the highlights here with photos from our EarthSky community. Have a great photo of your own to share? Submit it to us!
The morning of the Super Harvest Moon with Saturn
View at EarthSky Community Photos. | On the morning of the Harvest Moon, Joel Weatherly in Edmonton, Alberta, Canada, caught “Saturn moments away from disappearing behind the limb of the moon.” Stunning! Thank you, Joel!
View at EarthSky Community Photos. | Carol Kuehn was “looking across Keuka Lake at the hilltop on the western horizon” in New York when she caught the setting Harvest Moon on the morning of September 18, 2024. Thank you, Carol!View at EarthSky Community Photos. | Nicole Wascoe Bauman caught the setting Harvest Moon on the morning of September 18, 2024, from Albuquerque, New Mexico. Nicole wrote: “After a long night lighting up the sky, the Harvest Supermoon has one last hurrah in the western sky over Mt. Taylor.” Thanks, Nicole!
Bottom line: The Super Harvest Moon on September 17, 2024, was briefly darkened by Earth’s shadow in a partial lunar eclipse. Check out some great photos of the event here!
Neanderthal man facial reconstruction via the Natural History Museum in London. Neanderthals lived in Europe through the Ice Ages and until the arrival of “modern” man some 40,000 years ago. Image via Wikimedia Commons (CC BY-SA 2.0).
Neanderthals, like “Thorin” found in France, lived in small, isolated groups without much interaction with other Neanderthal populations. Scientists think this isolation might have led to inbreeding and ultimate extinction.
Thorin’s lineage split from other Neanderthals about 100,000 years ago, according to DNA analysis. The lineage remained separate for over 50,000 years, suggesting more complex population structures than previously thought.
The isolation likely reduced genetic diversity, making Neanderthals less adaptable to changing environments and contributing to their eventual demise.
How did Neanderthals become extinct?
Neanderthals are an ancient human species that once lived in Europe and parts of Asia. Scientists think they emerged 400,000 years ago and became extinct about 40,000 years ago. No one knows why they disappeared. One theory is that Neanderthal populations became too isolated from each other. As a result, they eventually died out due to inbreeding. On September 12, 2024, the University of Copenhagen said new DNA analysis of Neanderthal remains from a cave in southern France makes that theory more likely.
For more than two decades, scientists have been extracting and studying ancient DNA from the remains of Neanderthals. This has allowed them to study differences in populations scattered across Europe and Asia.
The latest contributor to Neanderthal genome studies – the study of genetic material – is “Thorin,” a Neanderthal found in southern France. It’s a nickname bestowed by the scientists who found him, adopted from a character in J. R. R. Tolkien’s novel “The Hobbit.”
Researchers discovered Thorin in 2015 in a Rhône River Valley cave in France called Grotte Mandrin. Excavations of his remains are still ongoing. So far, scientists have recovered and studied parts of his jaws, with teeth still attached.
Analysis of his remains indicate he lived about 42,000 to 50,000 years ago.
The cleaned and prepared fossil jaws and teeth of the Neanderthal known as Thorin. DNA studies of this fossil support the theory that Neanderthals became extinct because their populations were isolated, leading to inbreeding. Image via Xavier Muth/ University of Copenhagen.
Studying Neanderthals using DNA analysis
Researchers were able to extract DNA samples from Thorin’s teeth and jaw. Then they compared that DNA to samples from other Neanderthals in Europe and Asia.
Their analysis revealed Thorin came from a previously unknown lineage. His DNA was similar to an earlier Neanderthal population from about 100,000 years ago. However, geological dating methods indicated Thorin’s remains were much younger, between 42,000 to 50,000 years old. This age discrepancy puzzled the scientists, so they used additional analysis methods to date the remains.
Thorin’s remains, it turns out, were between 42,000 to 50,000 years old. He had descended from a population that had undergone little genetic changes for over 50,000 years.
Fossilized teeth and jaw of the Neanderthal known as Thorin while still in the ground. Image via Ludovik Slimak/ EurekAlert!.
A new look at an ancient population
According to paper author Tharsika Vimala, of the University of Copenhagen, scientists once thought that before Neanderthals became extinct 40,000 years ago, there was just one population. Thorin’s DNA results revealed there were actually two Neanderthal populations living in the same vicinity at the same time. She said:
Until now, the story has been that at the time of the extinction there was just one Neanderthal population that was genetically homogeneous, but now we know that there were at least two populations present at that time.
The Thorin population spent 50,000 years without exchanging genes with other Neanderthal populations. We thus have 50 millennia during which two Neanderthal populations, living about ten days’ walk from each other, coexisted while completely ignoring each other. This would be unimaginable for a Sapiens [modern humans] and reveals that Neanderthals must have biologically conceived our world very differently from us Sapiens.
Social isolation led to inbreeding in Neanderthals
This study raises interesting questions about the lack of social interactions between Neanderthal populations, and how it may have played a role in their demise.
It’s always a good thing for a population to be in contact with other populations. When you are isolated for a long time, you limit the genetic variation you have, which means you have less ability to adapt to changing climates and pathogens, and it also limits you socially because you’re not sharing knowledge or evolving as a population.
When we look at these genomes from Neanderthals, we see they are quite inbred and therefore don’t have much genetic diversity. They have been living in small groups for many generations. We know inbreeding reduces genetic diversity in a population, which can be detrimental to their ability to survive if it occurs over a longer term.
The newly found Neanderthal genome is from a different lineage than the other late Neanderthals previously studied. This supports the notion that social organization of Neanderthals was different to early modern humans who seemed to have been more connected.
A different world from modern humans
Vimala added:
This is in the more speculative end, but even just the notion of being able to communicate more and exchange knowledge is something humans do that Neanderthals to some extend might not have done, due to their isolated lifestyles by organizing themselves in smaller groups. And that is an important skill to have. We see evidence of early modern humans in Siberia forming so-called mating networks to avoid issues with inbreeding, while living in small communities, which is something we haven’t seen with Neanderthals.
Bottom line: Some scientists think Neanderthals became extinct because their populations became too isolated, leading to inbreeding. New DNA studies of a Neanderthal in France support this theory.
Neanderthal man facial reconstruction via the Natural History Museum in London. Neanderthals lived in Europe through the Ice Ages and until the arrival of “modern” man some 40,000 years ago. Image via Wikimedia Commons (CC BY-SA 2.0).
Neanderthals, like “Thorin” found in France, lived in small, isolated groups without much interaction with other Neanderthal populations. Scientists think this isolation might have led to inbreeding and ultimate extinction.
Thorin’s lineage split from other Neanderthals about 100,000 years ago, according to DNA analysis. The lineage remained separate for over 50,000 years, suggesting more complex population structures than previously thought.
The isolation likely reduced genetic diversity, making Neanderthals less adaptable to changing environments and contributing to their eventual demise.
How did Neanderthals become extinct?
Neanderthals are an ancient human species that once lived in Europe and parts of Asia. Scientists think they emerged 400,000 years ago and became extinct about 40,000 years ago. No one knows why they disappeared. One theory is that Neanderthal populations became too isolated from each other. As a result, they eventually died out due to inbreeding. On September 12, 2024, the University of Copenhagen said new DNA analysis of Neanderthal remains from a cave in southern France makes that theory more likely.
For more than two decades, scientists have been extracting and studying ancient DNA from the remains of Neanderthals. This has allowed them to study differences in populations scattered across Europe and Asia.
The latest contributor to Neanderthal genome studies – the study of genetic material – is “Thorin,” a Neanderthal found in southern France. It’s a nickname bestowed by the scientists who found him, adopted from a character in J. R. R. Tolkien’s novel “The Hobbit.”
Researchers discovered Thorin in 2015 in a Rhône River Valley cave in France called Grotte Mandrin. Excavations of his remains are still ongoing. So far, scientists have recovered and studied parts of his jaws, with teeth still attached.
Analysis of his remains indicate he lived about 42,000 to 50,000 years ago.
The cleaned and prepared fossil jaws and teeth of the Neanderthal known as Thorin. DNA studies of this fossil support the theory that Neanderthals became extinct because their populations were isolated, leading to inbreeding. Image via Xavier Muth/ University of Copenhagen.
Studying Neanderthals using DNA analysis
Researchers were able to extract DNA samples from Thorin’s teeth and jaw. Then they compared that DNA to samples from other Neanderthals in Europe and Asia.
Their analysis revealed Thorin came from a previously unknown lineage. His DNA was similar to an earlier Neanderthal population from about 100,000 years ago. However, geological dating methods indicated Thorin’s remains were much younger, between 42,000 to 50,000 years old. This age discrepancy puzzled the scientists, so they used additional analysis methods to date the remains.
Thorin’s remains, it turns out, were between 42,000 to 50,000 years old. He had descended from a population that had undergone little genetic changes for over 50,000 years.
Fossilized teeth and jaw of the Neanderthal known as Thorin while still in the ground. Image via Ludovik Slimak/ EurekAlert!.
A new look at an ancient population
According to paper author Tharsika Vimala, of the University of Copenhagen, scientists once thought that before Neanderthals became extinct 40,000 years ago, there was just one population. Thorin’s DNA results revealed there were actually two Neanderthal populations living in the same vicinity at the same time. She said:
Until now, the story has been that at the time of the extinction there was just one Neanderthal population that was genetically homogeneous, but now we know that there were at least two populations present at that time.
The Thorin population spent 50,000 years without exchanging genes with other Neanderthal populations. We thus have 50 millennia during which two Neanderthal populations, living about ten days’ walk from each other, coexisted while completely ignoring each other. This would be unimaginable for a Sapiens [modern humans] and reveals that Neanderthals must have biologically conceived our world very differently from us Sapiens.
Social isolation led to inbreeding in Neanderthals
This study raises interesting questions about the lack of social interactions between Neanderthal populations, and how it may have played a role in their demise.
It’s always a good thing for a population to be in contact with other populations. When you are isolated for a long time, you limit the genetic variation you have, which means you have less ability to adapt to changing climates and pathogens, and it also limits you socially because you’re not sharing knowledge or evolving as a population.
When we look at these genomes from Neanderthals, we see they are quite inbred and therefore don’t have much genetic diversity. They have been living in small groups for many generations. We know inbreeding reduces genetic diversity in a population, which can be detrimental to their ability to survive if it occurs over a longer term.
The newly found Neanderthal genome is from a different lineage than the other late Neanderthals previously studied. This supports the notion that social organization of Neanderthals was different to early modern humans who seemed to have been more connected.
A different world from modern humans
Vimala added:
This is in the more speculative end, but even just the notion of being able to communicate more and exchange knowledge is something humans do that Neanderthals to some extend might not have done, due to their isolated lifestyles by organizing themselves in smaller groups. And that is an important skill to have. We see evidence of early modern humans in Siberia forming so-called mating networks to avoid issues with inbreeding, while living in small communities, which is something we haven’t seen with Neanderthals.
Bottom line: Some scientists think Neanderthals became extinct because their populations became too isolated, leading to inbreeding. New DNA studies of a Neanderthal in France support this theory.
Watch a video of the EarthSky’s stargazing tips for beginning astronomers.
Our top 10 stargazing tips for beginners
Stargazing is for everybody. It’s for people who view the night sky with a sense of wonder … and people who just like being outside at night. Maybe that’s you. If so – and if you’re a beginner – here are some tips to help you get started. And remember like anything, stargazing takes practice. And soon you’ll be able to point out stars, constellations and planets.
View at EarthSky Community Photos. | Stojan Stojanovski in Bitola, Macedonia, captured this image on August 30, 2023. Stojan wrote: “My friend shows you the super Blue Moon tonight on the top of the mountain.” Thank you, Stojan! Anyone at any age can enjoy the night sky. Read our top 10 stargazing tips for beginners here.
Tip 1: Watch the moon
Earth’s companion moon is visible from city streets, suburban decks and wide-open rural pastures. The moon connects you to everybody on the planet, because, generally speaking, we all see the moon at the same phase (although, because we live on a round Earth with 24 time zones, not exactly at the same time). The moon’s orbit around Earth is regular and predictable. So the moon waxes and wanes in our sky in a way that’s about as satisfyingly regular and predictable as anything on Earth can be.
Try following it for one lunar cycle. Start looking for a crescent moon in the sunset direction a day or two after new moon and then check it out every night at about the same time. What do you notice? Is it getting fatter or thinner in phase? Does it move from night to night with respect to nearby bright stars or planets?
Then what happens after the full moon? You’ll notice it rises later each day and soon it’ll be visible only after midnight. And eventually it’ll appear above the horizon closer to the sunrise. That’s because during one complete lunar cycle, the moon spends half of its time in the night sky and half of the time in the daytime. So yes, you can sometimes see the moon in daylight. Track it for a month and see how it changes. To learn more, check out our article on 4 keys to understanding moon phases.
And remember, the moon can help you locate stars and planets. Check our visible planet and night guide to sky to see what’s currently visible in the night sky.
View at EarthSky Community Photos. | Chuck Reinhart from Vincennes, Indiana, shared this photo with us and wrote: “Shortly after sunset, I was able to capture Mars, Venus and the crescent moon with some earthshine.” Thank you, Chuck!
Tip 2: Watch the sun
Don’t look directly at it, of course. But do notice the point on the horizon where the sun rises or sets as seen from your kitchen window, balcony or yard. Does that rising or setting point change as the seasons pass? Does the path of the sun from east to west during the day change?
The sun rises due east and sets due west at every equinox. If you identify east and west, you’ll have a jump on our next activity. By the way, try this great custom calendar at Sunrise Sunset Calendars. Don’t forget to check the moon phase box, too!
The Internet is great, but a computer is an unwieldy companion on stargazing adventures. What you want is a printed chart. Start with the easy-to-use charts at EarthSky Tonight. These daily charts are geared toward beginners, and each one presents something interesting to spot in that night’s sky. Then take the plunge and purchase a printed chart, maybe one of the planispheres in our store.
In just a few weeks of using our daily EarthSky Tonight area – plus a planisphere – you will quickly raise your stargazing IQ. Still want an online chart? Try Stellarium.
A planisphere will teach you what stars and constellations are overhead for any night of the year. Image via EarthSky.
Tip 4: Don’t buy a telescope yet
Remember that pair of binoculars you stuck way at the top of your closet? Point them at the moon and bright objects in the night sky. Do you see anything you hadn’t noticed before? Point them at noticeable star patterns; for example, the second star from the end of the Big Dipper’s handle is really two stars.
If you’re in a dark location, use your binoculars to sweep along the Milky Way and to check out any hazy patches in the night sky. These patches may be actual named star clusters, or they may be clouds of gas and dust where new stars are forming. You don’t need to know what you’re seeing to enjoy the beauty of it all.
This chart of the Big Dipper includes a label for Mizar, while its companion star, Alcor, appears next to it without a label. Can you see both stars with or without binoculars?
Tip 5: Notice patterns among the stars
Here’s how most stargazers learn constellations. They find a noticeable pattern, and then they notice another pattern nearby. They build outward, going from stars and patterns they know to new ones. Notice triangles, curves and straight lines of stars. Some of these patterns are the same ones our ancestors noticed while sitting around a campfire telling stories. Some of their stories ended up being passed down to us. Make up your own stories!
View at EarthSky Community Photos. | Cecille Kennedy captured this shot of the Northern Cross on September 17, 2023, from Oregon. Thank you, Cecille! The Northern Cross is a clipped version of the constellation Cygnus the Swan. It’s an asterism, or pattern of stars. It lies embedded within another much larger asterism: the Summer Triangle, made up of the 3 brightest stars you can see in Cecille’s picture.
Tip 6: Find a dark-sky site
Try a state park or a national park. You won’t be sorry. Visit EarthSky’s Best Places to Stargaze page for dark locations around the world. Check also for an astronomy club in your area. Experienced members are good sources of advice, and some groups loan out telescopes. Many societies also have libraries stocked with specialized books and atlases often not found in public libraries. Astronomy is also a good hobby to enjoy with a friend or family member. The delight of discovery is infectious.
And leave electronics in your pocket or vehicle. Even night mode is too bright under a dark sky and will ruin your night vision. Use a red flashlight to read your star charts or planisphere.
View at EarthSky Community Photos. | Thomas Frazier in Virginia took this wonderful image of his daughter on June 30, 2022, while contemplating the amazing Milky Way. He wrote: “My daughter and I went to Sky Meadows State Park. After viewing various galaxies, nebulae and globular clusters on my telescope, we tried this shot. Sky Meadows was recently named an International Dark Skies site. The glow on the horizon is the Washington, D.C., metro area.” Thank you, Thomas!
Tip 7: Link up with astro-friends
If you live in a college town, keep an eye out for astronomy community enrichment courses. Local schools, museums and planetariums might also host public programs.
Universities often hold public observing nights at their observatories. Pictured here, Washburn Observatory at the University of Wisconsin-Madison. Image via Wikimedia Commons (CC BY 3.0).
Tip 8: Take the telescope plunge carefully
Have you been watching the night sky for half a year at least? Can you recognize some major constellations? Have you identified a planet or two? The time to buy a telescope is when you’ve given yourself time to acclimate to the sky around you and all its nuances. Before that, if you want more optical power, buy binoculars. Once you’re ready to take the plunge, check these things to know before buying a telescope from High Point Scientific.
View at EarthSky Community Photos. | Dr Ski at Valencia Observatory, Central Philippines, took this image and wrote: “The Omega Centauri globular cluster is the only deep sky object I can capture at high magnification with a pocket camera and no tracking mount! It’s that spectacular. Unlike many astrophotographs, this image is exactly what you can expect to see thru a small telescope at 40x. No embellishments here.” Thank you, Dr Ski!
Tip 9: Just look up
Most of us go through life looking straight ahead. But you’ve got to look up to see stars. Standing outside at a bus stop? Look at the sky. In your car? Look out the window, carefully. Going outside before sunup to grab the paper? Gaze toward the sunrise horizon. Notice bright objects in the sky. Notice patterns among the stars. Just start looking up and noticing.
View at EarthSky Community Photos. | Prateek Pandey in Bhopal, Madhya Pradesh, India, captured this photo of Boötes, Virgo and Corona Borealis. He wrote: “Spring constellations twinkling in the eastern horizon.” Thank you, Prateek!
Tip 10: Be faithful to the sky
One of the great things about becoming a stargazer is that you make a lifelong friend: the sky itself. It’s a friend that lives right next door. And like any friend, the sky changes in subtle ways from day to day and year to year. So, once you start watching it, be patient. You can’t learn everything about your friend at once. Be persistent. Watch the sky a lot and watch regularly. You’ll learn by looking! And you’ll make a connection with nature that’ll last your whole life long.
View at EarthSky Community Photos. | Steve Price in the Last Chance Desert, Utah, took this image and wrote: “New moon phase during July 2021 … Approximately 15 miles into The Last Chance Desert near Solomon’s Temple sandstone monolith … a great night to be alone in the desert with the stars and a few mammals scurrying around.” Thank you, Steve!
Bottom line: If you’re new to observing the night sky, check out our top 10 stargazing tips for beginners. We’ll help you explore and expand your love for astronomy.
Watch a video of the EarthSky’s stargazing tips for beginning astronomers.
Our top 10 stargazing tips for beginners
Stargazing is for everybody. It’s for people who view the night sky with a sense of wonder … and people who just like being outside at night. Maybe that’s you. If so – and if you’re a beginner – here are some tips to help you get started. And remember like anything, stargazing takes practice. And soon you’ll be able to point out stars, constellations and planets.
View at EarthSky Community Photos. | Stojan Stojanovski in Bitola, Macedonia, captured this image on August 30, 2023. Stojan wrote: “My friend shows you the super Blue Moon tonight on the top of the mountain.” Thank you, Stojan! Anyone at any age can enjoy the night sky. Read our top 10 stargazing tips for beginners here.
Tip 1: Watch the moon
Earth’s companion moon is visible from city streets, suburban decks and wide-open rural pastures. The moon connects you to everybody on the planet, because, generally speaking, we all see the moon at the same phase (although, because we live on a round Earth with 24 time zones, not exactly at the same time). The moon’s orbit around Earth is regular and predictable. So the moon waxes and wanes in our sky in a way that’s about as satisfyingly regular and predictable as anything on Earth can be.
Try following it for one lunar cycle. Start looking for a crescent moon in the sunset direction a day or two after new moon and then check it out every night at about the same time. What do you notice? Is it getting fatter or thinner in phase? Does it move from night to night with respect to nearby bright stars or planets?
Then what happens after the full moon? You’ll notice it rises later each day and soon it’ll be visible only after midnight. And eventually it’ll appear above the horizon closer to the sunrise. That’s because during one complete lunar cycle, the moon spends half of its time in the night sky and half of the time in the daytime. So yes, you can sometimes see the moon in daylight. Track it for a month and see how it changes. To learn more, check out our article on 4 keys to understanding moon phases.
And remember, the moon can help you locate stars and planets. Check our visible planet and night guide to sky to see what’s currently visible in the night sky.
View at EarthSky Community Photos. | Chuck Reinhart from Vincennes, Indiana, shared this photo with us and wrote: “Shortly after sunset, I was able to capture Mars, Venus and the crescent moon with some earthshine.” Thank you, Chuck!
Tip 2: Watch the sun
Don’t look directly at it, of course. But do notice the point on the horizon where the sun rises or sets as seen from your kitchen window, balcony or yard. Does that rising or setting point change as the seasons pass? Does the path of the sun from east to west during the day change?
The sun rises due east and sets due west at every equinox. If you identify east and west, you’ll have a jump on our next activity. By the way, try this great custom calendar at Sunrise Sunset Calendars. Don’t forget to check the moon phase box, too!
The Internet is great, but a computer is an unwieldy companion on stargazing adventures. What you want is a printed chart. Start with the easy-to-use charts at EarthSky Tonight. These daily charts are geared toward beginners, and each one presents something interesting to spot in that night’s sky. Then take the plunge and purchase a printed chart, maybe one of the planispheres in our store.
In just a few weeks of using our daily EarthSky Tonight area – plus a planisphere – you will quickly raise your stargazing IQ. Still want an online chart? Try Stellarium.
A planisphere will teach you what stars and constellations are overhead for any night of the year. Image via EarthSky.
Tip 4: Don’t buy a telescope yet
Remember that pair of binoculars you stuck way at the top of your closet? Point them at the moon and bright objects in the night sky. Do you see anything you hadn’t noticed before? Point them at noticeable star patterns; for example, the second star from the end of the Big Dipper’s handle is really two stars.
If you’re in a dark location, use your binoculars to sweep along the Milky Way and to check out any hazy patches in the night sky. These patches may be actual named star clusters, or they may be clouds of gas and dust where new stars are forming. You don’t need to know what you’re seeing to enjoy the beauty of it all.
This chart of the Big Dipper includes a label for Mizar, while its companion star, Alcor, appears next to it without a label. Can you see both stars with or without binoculars?
Tip 5: Notice patterns among the stars
Here’s how most stargazers learn constellations. They find a noticeable pattern, and then they notice another pattern nearby. They build outward, going from stars and patterns they know to new ones. Notice triangles, curves and straight lines of stars. Some of these patterns are the same ones our ancestors noticed while sitting around a campfire telling stories. Some of their stories ended up being passed down to us. Make up your own stories!
View at EarthSky Community Photos. | Cecille Kennedy captured this shot of the Northern Cross on September 17, 2023, from Oregon. Thank you, Cecille! The Northern Cross is a clipped version of the constellation Cygnus the Swan. It’s an asterism, or pattern of stars. It lies embedded within another much larger asterism: the Summer Triangle, made up of the 3 brightest stars you can see in Cecille’s picture.
Tip 6: Find a dark-sky site
Try a state park or a national park. You won’t be sorry. Visit EarthSky’s Best Places to Stargaze page for dark locations around the world. Check also for an astronomy club in your area. Experienced members are good sources of advice, and some groups loan out telescopes. Many societies also have libraries stocked with specialized books and atlases often not found in public libraries. Astronomy is also a good hobby to enjoy with a friend or family member. The delight of discovery is infectious.
And leave electronics in your pocket or vehicle. Even night mode is too bright under a dark sky and will ruin your night vision. Use a red flashlight to read your star charts or planisphere.
View at EarthSky Community Photos. | Thomas Frazier in Virginia took this wonderful image of his daughter on June 30, 2022, while contemplating the amazing Milky Way. He wrote: “My daughter and I went to Sky Meadows State Park. After viewing various galaxies, nebulae and globular clusters on my telescope, we tried this shot. Sky Meadows was recently named an International Dark Skies site. The glow on the horizon is the Washington, D.C., metro area.” Thank you, Thomas!
Tip 7: Link up with astro-friends
If you live in a college town, keep an eye out for astronomy community enrichment courses. Local schools, museums and planetariums might also host public programs.
Universities often hold public observing nights at their observatories. Pictured here, Washburn Observatory at the University of Wisconsin-Madison. Image via Wikimedia Commons (CC BY 3.0).
Tip 8: Take the telescope plunge carefully
Have you been watching the night sky for half a year at least? Can you recognize some major constellations? Have you identified a planet or two? The time to buy a telescope is when you’ve given yourself time to acclimate to the sky around you and all its nuances. Before that, if you want more optical power, buy binoculars. Once you’re ready to take the plunge, check these things to know before buying a telescope from High Point Scientific.
View at EarthSky Community Photos. | Dr Ski at Valencia Observatory, Central Philippines, took this image and wrote: “The Omega Centauri globular cluster is the only deep sky object I can capture at high magnification with a pocket camera and no tracking mount! It’s that spectacular. Unlike many astrophotographs, this image is exactly what you can expect to see thru a small telescope at 40x. No embellishments here.” Thank you, Dr Ski!
Tip 9: Just look up
Most of us go through life looking straight ahead. But you’ve got to look up to see stars. Standing outside at a bus stop? Look at the sky. In your car? Look out the window, carefully. Going outside before sunup to grab the paper? Gaze toward the sunrise horizon. Notice bright objects in the sky. Notice patterns among the stars. Just start looking up and noticing.
View at EarthSky Community Photos. | Prateek Pandey in Bhopal, Madhya Pradesh, India, captured this photo of Boötes, Virgo and Corona Borealis. He wrote: “Spring constellations twinkling in the eastern horizon.” Thank you, Prateek!
Tip 10: Be faithful to the sky
One of the great things about becoming a stargazer is that you make a lifelong friend: the sky itself. It’s a friend that lives right next door. And like any friend, the sky changes in subtle ways from day to day and year to year. So, once you start watching it, be patient. You can’t learn everything about your friend at once. Be persistent. Watch the sky a lot and watch regularly. You’ll learn by looking! And you’ll make a connection with nature that’ll last your whole life long.
View at EarthSky Community Photos. | Steve Price in the Last Chance Desert, Utah, took this image and wrote: “New moon phase during July 2021 … Approximately 15 miles into The Last Chance Desert near Solomon’s Temple sandstone monolith … a great night to be alone in the desert with the stars and a few mammals scurrying around.” Thank you, Steve!
Bottom line: If you’re new to observing the night sky, check out our top 10 stargazing tips for beginners. We’ll help you explore and expand your love for astronomy.
The equinox is on September 22, 2024. At the equinoxes, the ecliptic and the celestial equator intersect. See the intersection point on this imaginary great circle, representing the dome of Earth’s sky? The celestial equator is directly above Earth’s equator. The ecliptic is the sun’s apparent path across our sky. And the celestial equator intersects your horizon at points due east and due west. That’s why – at every equinox, no matter where you are on the globe – the sun, on the celestial equator, rises due east and sets due west. Read more about the equinox sun below. Image via NASA.
It’s not true that day and night are precisely equal on the day of an equinox. But here’s an equinox fact that is true. The sun rises due east and sets due west at the equinox. It might seem counterintuitive. But it’s true no matter where you live on Earth (except at the North and South Poles). Here’s how to visualize it.
To understand the nearly due-east and due-west rising and setting of an equinox sun, you have to think of the reality of Earth in space. First think about why the sun’s path across our sky shifts from season to season. That’s because our world is tilted on its axis with respect to its orbit around the sun.
Our seasons result from the Earth’s rotational axis tilting 23.5 degrees out of the perpendicular to the ecliptic, or Earth’s orbital plane. Image via National Weather Service/ weather.gov.
Now think about what is an equinox. It’s an event that happens on the imaginary dome of Earth’s sky. And it marks that special moment when the sun crosses the celestial equator going from one hemisphere to the other. Of course, it also represents a point in Earth’s orbit.
The celestial equator
The celestial equator is a great circle dividing the imaginary celestial sphere into its northern and southern hemispheres. Additionally, the celestial equator wraps the sky directly above Earth’s equator. Following the September equinox, the sun crosses the celestial equator to enter the sky’s Southern Hemisphere.
All these components are imaginary, yet what happens at every equinox is very real. In fact, it’s as real as the sun’s passage across the sky each day and as real as the change of seasons.
It’s the same all over the globe
So no matter where you are on Earth (except for the North and South Poles), you have a due east and due west point on your horizon. That point marks the intersection of your horizon with the celestial equator, the imaginary great circle above the true equator of Earth.
And that’s why the sun rises close to due east and sets close to due west, for all of us, at the equinox. The equinox sun is on the celestial equator. Which means, no matter where you are on Earth, the celestial equator intersects your horizon at due east and due west.
This fact makes the day of an equinox a good day for finding east and west from your yard or favorite site for watching the sky. Just go outside around sunset or sunrise and notice the location of the sun on the horizon with respect to familiar landmarks.
If you do this, you’ll be able to use those landmarks to find those cardinal directions in the weeks and months ahead. Plus, you’ll know those directions long after Earth has moved on in its orbit around the sun.
The history of the seasons
Our ancestors may not have understood the equinoxes and solstices as events that occur during Earth’s yearly orbit around the sun. But if they were observant – and some were very observant indeed – they surely marked the day of the equinox as being midway between the sun’s lowest path across the sky in winter and highest path across the sky in summer.
Now we can say with reasonably high accuracy that the sun rises due east and sets due west on the day of the equinox. And this is the same for everyone around the globe.
If you are seeking more precision for the sunrise/sunset direction in your part of the world, check out the altitude/azimuth for the sun via timeanddate.com.
EarthSky’s Raúl Cortés caught the March equinox sun at sunrise in 2021. Thanks, Raúl! See more of Raúl’s photos here.
Bottom line: The 2024 September equinox occurs on September 22 at 12:44 UTC (7:44 a.m. CDT). At the equinox, the sun rises and sets due east and due west.
The equinox is on September 22, 2024. At the equinoxes, the ecliptic and the celestial equator intersect. See the intersection point on this imaginary great circle, representing the dome of Earth’s sky? The celestial equator is directly above Earth’s equator. The ecliptic is the sun’s apparent path across our sky. And the celestial equator intersects your horizon at points due east and due west. That’s why – at every equinox, no matter where you are on the globe – the sun, on the celestial equator, rises due east and sets due west. Read more about the equinox sun below. Image via NASA.
It’s not true that day and night are precisely equal on the day of an equinox. But here’s an equinox fact that is true. The sun rises due east and sets due west at the equinox. It might seem counterintuitive. But it’s true no matter where you live on Earth (except at the North and South Poles). Here’s how to visualize it.
To understand the nearly due-east and due-west rising and setting of an equinox sun, you have to think of the reality of Earth in space. First think about why the sun’s path across our sky shifts from season to season. That’s because our world is tilted on its axis with respect to its orbit around the sun.
Our seasons result from the Earth’s rotational axis tilting 23.5 degrees out of the perpendicular to the ecliptic, or Earth’s orbital plane. Image via National Weather Service/ weather.gov.
Now think about what is an equinox. It’s an event that happens on the imaginary dome of Earth’s sky. And it marks that special moment when the sun crosses the celestial equator going from one hemisphere to the other. Of course, it also represents a point in Earth’s orbit.
The celestial equator
The celestial equator is a great circle dividing the imaginary celestial sphere into its northern and southern hemispheres. Additionally, the celestial equator wraps the sky directly above Earth’s equator. Following the September equinox, the sun crosses the celestial equator to enter the sky’s Southern Hemisphere.
All these components are imaginary, yet what happens at every equinox is very real. In fact, it’s as real as the sun’s passage across the sky each day and as real as the change of seasons.
It’s the same all over the globe
So no matter where you are on Earth (except for the North and South Poles), you have a due east and due west point on your horizon. That point marks the intersection of your horizon with the celestial equator, the imaginary great circle above the true equator of Earth.
And that’s why the sun rises close to due east and sets close to due west, for all of us, at the equinox. The equinox sun is on the celestial equator. Which means, no matter where you are on Earth, the celestial equator intersects your horizon at due east and due west.
This fact makes the day of an equinox a good day for finding east and west from your yard or favorite site for watching the sky. Just go outside around sunset or sunrise and notice the location of the sun on the horizon with respect to familiar landmarks.
If you do this, you’ll be able to use those landmarks to find those cardinal directions in the weeks and months ahead. Plus, you’ll know those directions long after Earth has moved on in its orbit around the sun.
The history of the seasons
Our ancestors may not have understood the equinoxes and solstices as events that occur during Earth’s yearly orbit around the sun. But if they were observant – and some were very observant indeed – they surely marked the day of the equinox as being midway between the sun’s lowest path across the sky in winter and highest path across the sky in summer.
Now we can say with reasonably high accuracy that the sun rises due east and sets due west on the day of the equinox. And this is the same for everyone around the globe.
If you are seeking more precision for the sunrise/sunset direction in your part of the world, check out the altitude/azimuth for the sun via timeanddate.com.
EarthSky’s Raúl Cortés caught the March equinox sun at sunrise in 2021. Thanks, Raúl! See more of Raúl’s photos here.
Bottom line: The 2024 September equinox occurs on September 22 at 12:44 UTC (7:44 a.m. CDT). At the equinox, the sun rises and sets due east and due west.
An artist’s depiction shows a black hole (at left) flying past Mars (right). If dark matter is mainly in the form of microscopic black holes, then their passage through the solar system could create detectable changes in the orbit of Mars. Image via MIT. Used with permission.
Dark matter may be made up of tiny primordial black holes, say MIT researchers.
Mars’ orbit may wobble slightly as these black holes pass through the solar system.
The idea that primordial black holes are a major source of dark matter would be bolstered by detecting such a wobble.
Watching for changes in the red planet’s orbit over time could be a way to detect passing dark matter
In a new study, MIT physicists propose that if most of the dark matter in the universe is made up of microscopic primordial black holes – an idea first proposed in the 1970s – then these gravitational dwarfs should zoom through our solar system at least once per decade. A flyby like this, the researchers predict, would introduce a wobble into Mars’ orbit, to a degree that today’s technology could actually detect.
Such a detection could lend support to the idea that primordial black holes are a primary source of dark matter throughout the universe.
Study author David Kaiser is a professor of physics and the Germeshausen Professor of the History of Science at MIT. He explained what the team hopes to see:
Given decades of precision telemetry, scientists know the distance between Earth and Mars to an accuracy of about 10 centimeters [4 inches]. We’re taking advantage of this highly instrumented region of space to try and look for a small effect. If we see it, that would count as a real reason to keep pursuing this delightful idea that all of dark matter consists of black holes that were spawned in less than a second after the Big Bang and have been streaming around the universe for 14 billion years.
Kaiser and his colleagues report their findings in the journal Physical Review D. The study’s co-authors are lead author Tung Tran, who is now a graduate student at Stanford University; Sarah Geller, who is now a postdoc at the University of California at Santa Cruz; and MIT Pappalardo Fellow Benjamin Lehmann.
Dark matter may not be made of particles
Less than 20% of all physical matter is made from visible stuff, from stars and planets, to the kitchen sink. The rest is composed of dark matter, a hypothetical form of matter that is invisible across the entire electromagnetic spectrum yet is thought to pervade the universe and exert a gravitational force large enough to affect the motion of stars and galaxies.
Physicists have erected detectors on Earth to try and spot dark matter and pin down its properties. For the most part, these experiments assume that dark matter exists as a form of exotic particle that might scatter and decay into observable particles as it passes through a given experiment. But so far, such particle-based searches have come up empty.
In recent years, another possibility, first introduced in the 1970s, has regained traction: rather than taking on a particle form, dark matter could exist as microscopic, primordial black holes that formed in the first moments following the Big Bang. Unlike the astrophysical black holes that form from the collapse of old stars, primordial black holes would have formed from the collapse of dense pockets of gas in the very early universe and would have scattered across the cosmos as the universe expanded and cooled.
Dark matter black holes could compact lots of mass in a little space
These primordial black holes would have collapsed an enormous amount of mass into a tiny space. The majority of these primordial black holes could be as small as a single atom and as heavy as the largest asteroids. It would be conceivable, then, that such tiny giants could exert a gravitational force that could explain at least a portion of dark matter. For the MIT team, this possibility raised an initially frivolous question.
Tung recalled the odd question that started their study:
I think someone asked me what would happen if a primordial black hole passed through a human body.
Tung did a quick pencil-and-paper calculation to find that if such a black hole zinged within 1 meter of a person, the force of the black hole would push the person 6 meters, or about 20 feet away in a single second. Tung also found that the odds were astronomically unlikely that a primordial black hole would pass anywhere near a person on Earth.
Their interest piqued, the researchers took Tung’s calculations a step further, to estimate how a black hole flyby might affect much larger bodies such as the Earth and the moon. Tung explained:
We extrapolated to see what would happen if a black hole flew by Earth and caused the moon to wobble by a little bit. The numbers we got were not very clear. There are many other dynamics in the solar system that could act as some sort of friction to cause the wobble to dampen out.
Close encounters of the primordial kind probably happen often
To get a clearer picture, the team generated a relatively simple simulation of the solar system that incorporates the orbits and gravitational interactions between all the planets and some of the largest moons.
Study author Lehmann said:
State-of-the-art simulations of the solar system include more than a million objects, each of which has a tiny residual effect. But even modeling two dozen objects in a careful simulation, we could see there was a real effect that we could dig into.
The team worked out the rate at which a primordial black hole should pass through the solar system, based on the amount of dark matter that is estimated to reside in a given region of space and the mass of a passing black hole, which in this case, they assumed to be as massive as the largest asteroids in the solar system, consistent with other astrophysical constraints.
Author Sarah Geller explained:
Primordial black holes do not live in the solar system. Rather, they’re streaming through the universe, doing their own thing. And the probability is, they’re going through the inner solar system at some angle once every 10 years or so.
Fast-moving black holes may be pushing Mars around
Given this rate, the researchers simulated various asteroid-mass black holes flying through the solar system, from various angles, and at velocities of about 150 miles per second (240 km/s). (The directions and speeds come from other studies of the distribution of dark matter throughout our galaxy.) They zeroed in on those flybys that appeared to be “close encounters,” or instances that caused some sort of effect in surrounding objects. They quickly found that any effect in the Earth or the moon was too uncertain to pin to a particular black hole. But Mars seemed to offer a clearer picture.
The researchers found that if a primordial black hole were to pass within a few hundred million miles of Mars, the encounter would set off a “wobble,” or a slight deviation in Mars’ orbit. Within a few years of such an encounter, Mars’ orbit should shift by about a meter (yard), an incredibly small wobble, given the planet is more than 140 million miles (225 million km) from Earth. And yet, this wobble could be detected by the various high-precision instruments that are monitoring Mars today.
If such a wobble were detected in the next couple of decades, the researchers acknowledge there would still be much work needed to confirm that the push came from a passing black hole rather than a run-of-the-mill asteroid.
Better solar system simulation will aid black hole search
Study author Kaiser explained how the search will identify black hole pushes:
We need as much clarity as we can of the expected backgrounds, such as the typical speeds and distributions of boring space rocks, versus these primordial black holes. Luckily for us, astronomers have been tracking ordinary space rocks for decades as they have flown through our solar system, so we could calculate typical properties of their trajectories and begin to compare them with the very different types of paths and speeds that primordial black holes should follow.
To help with this, the researchers are exploring the possibility of a new collaboration with a group that has extensive expertise simulating many more objects in the solar system.
Geller said the team is refining its solar system simulation for better results:
We are now working to simulate a huge number of objects, from planets to moons and rocks, and how they’re all moving over long time scales. We want to inject close encounter scenarios, and look at their effects with higher precision.
Black hole search will require much effort
Matt Caplan, an associate professor of physics at Illinois State University who was not involved in the study, said the MIT team is just starting the real work:
It’s a very neat test they’ve proposed, and it could tell us if the closest black hole is closer than we realize. I should emphasize there’s a little bit of luck involved too. Whether or not a search finds a loud and clear signal depends on the exact path a wandering black hole takes through the solar system. Now that they’ve checked this idea with simulations, they have to do the hard part: checking the real data.
Bottom line: MIT researchers believe dark matter exists in the form of tiny black holes. Those black holes may cause Mars’ orbit to wobble, making them detectable.
An artist’s depiction shows a black hole (at left) flying past Mars (right). If dark matter is mainly in the form of microscopic black holes, then their passage through the solar system could create detectable changes in the orbit of Mars. Image via MIT. Used with permission.
Dark matter may be made up of tiny primordial black holes, say MIT researchers.
Mars’ orbit may wobble slightly as these black holes pass through the solar system.
The idea that primordial black holes are a major source of dark matter would be bolstered by detecting such a wobble.
Watching for changes in the red planet’s orbit over time could be a way to detect passing dark matter
In a new study, MIT physicists propose that if most of the dark matter in the universe is made up of microscopic primordial black holes – an idea first proposed in the 1970s – then these gravitational dwarfs should zoom through our solar system at least once per decade. A flyby like this, the researchers predict, would introduce a wobble into Mars’ orbit, to a degree that today’s technology could actually detect.
Such a detection could lend support to the idea that primordial black holes are a primary source of dark matter throughout the universe.
Study author David Kaiser is a professor of physics and the Germeshausen Professor of the History of Science at MIT. He explained what the team hopes to see:
Given decades of precision telemetry, scientists know the distance between Earth and Mars to an accuracy of about 10 centimeters [4 inches]. We’re taking advantage of this highly instrumented region of space to try and look for a small effect. If we see it, that would count as a real reason to keep pursuing this delightful idea that all of dark matter consists of black holes that were spawned in less than a second after the Big Bang and have been streaming around the universe for 14 billion years.
Kaiser and his colleagues report their findings in the journal Physical Review D. The study’s co-authors are lead author Tung Tran, who is now a graduate student at Stanford University; Sarah Geller, who is now a postdoc at the University of California at Santa Cruz; and MIT Pappalardo Fellow Benjamin Lehmann.
Dark matter may not be made of particles
Less than 20% of all physical matter is made from visible stuff, from stars and planets, to the kitchen sink. The rest is composed of dark matter, a hypothetical form of matter that is invisible across the entire electromagnetic spectrum yet is thought to pervade the universe and exert a gravitational force large enough to affect the motion of stars and galaxies.
Physicists have erected detectors on Earth to try and spot dark matter and pin down its properties. For the most part, these experiments assume that dark matter exists as a form of exotic particle that might scatter and decay into observable particles as it passes through a given experiment. But so far, such particle-based searches have come up empty.
In recent years, another possibility, first introduced in the 1970s, has regained traction: rather than taking on a particle form, dark matter could exist as microscopic, primordial black holes that formed in the first moments following the Big Bang. Unlike the astrophysical black holes that form from the collapse of old stars, primordial black holes would have formed from the collapse of dense pockets of gas in the very early universe and would have scattered across the cosmos as the universe expanded and cooled.
Dark matter black holes could compact lots of mass in a little space
These primordial black holes would have collapsed an enormous amount of mass into a tiny space. The majority of these primordial black holes could be as small as a single atom and as heavy as the largest asteroids. It would be conceivable, then, that such tiny giants could exert a gravitational force that could explain at least a portion of dark matter. For the MIT team, this possibility raised an initially frivolous question.
Tung recalled the odd question that started their study:
I think someone asked me what would happen if a primordial black hole passed through a human body.
Tung did a quick pencil-and-paper calculation to find that if such a black hole zinged within 1 meter of a person, the force of the black hole would push the person 6 meters, or about 20 feet away in a single second. Tung also found that the odds were astronomically unlikely that a primordial black hole would pass anywhere near a person on Earth.
Their interest piqued, the researchers took Tung’s calculations a step further, to estimate how a black hole flyby might affect much larger bodies such as the Earth and the moon. Tung explained:
We extrapolated to see what would happen if a black hole flew by Earth and caused the moon to wobble by a little bit. The numbers we got were not very clear. There are many other dynamics in the solar system that could act as some sort of friction to cause the wobble to dampen out.
Close encounters of the primordial kind probably happen often
To get a clearer picture, the team generated a relatively simple simulation of the solar system that incorporates the orbits and gravitational interactions between all the planets and some of the largest moons.
Study author Lehmann said:
State-of-the-art simulations of the solar system include more than a million objects, each of which has a tiny residual effect. But even modeling two dozen objects in a careful simulation, we could see there was a real effect that we could dig into.
The team worked out the rate at which a primordial black hole should pass through the solar system, based on the amount of dark matter that is estimated to reside in a given region of space and the mass of a passing black hole, which in this case, they assumed to be as massive as the largest asteroids in the solar system, consistent with other astrophysical constraints.
Author Sarah Geller explained:
Primordial black holes do not live in the solar system. Rather, they’re streaming through the universe, doing their own thing. And the probability is, they’re going through the inner solar system at some angle once every 10 years or so.
Fast-moving black holes may be pushing Mars around
Given this rate, the researchers simulated various asteroid-mass black holes flying through the solar system, from various angles, and at velocities of about 150 miles per second (240 km/s). (The directions and speeds come from other studies of the distribution of dark matter throughout our galaxy.) They zeroed in on those flybys that appeared to be “close encounters,” or instances that caused some sort of effect in surrounding objects. They quickly found that any effect in the Earth or the moon was too uncertain to pin to a particular black hole. But Mars seemed to offer a clearer picture.
The researchers found that if a primordial black hole were to pass within a few hundred million miles of Mars, the encounter would set off a “wobble,” or a slight deviation in Mars’ orbit. Within a few years of such an encounter, Mars’ orbit should shift by about a meter (yard), an incredibly small wobble, given the planet is more than 140 million miles (225 million km) from Earth. And yet, this wobble could be detected by the various high-precision instruments that are monitoring Mars today.
If such a wobble were detected in the next couple of decades, the researchers acknowledge there would still be much work needed to confirm that the push came from a passing black hole rather than a run-of-the-mill asteroid.
Better solar system simulation will aid black hole search
Study author Kaiser explained how the search will identify black hole pushes:
We need as much clarity as we can of the expected backgrounds, such as the typical speeds and distributions of boring space rocks, versus these primordial black holes. Luckily for us, astronomers have been tracking ordinary space rocks for decades as they have flown through our solar system, so we could calculate typical properties of their trajectories and begin to compare them with the very different types of paths and speeds that primordial black holes should follow.
To help with this, the researchers are exploring the possibility of a new collaboration with a group that has extensive expertise simulating many more objects in the solar system.
Geller said the team is refining its solar system simulation for better results:
We are now working to simulate a huge number of objects, from planets to moons and rocks, and how they’re all moving over long time scales. We want to inject close encounter scenarios, and look at their effects with higher precision.
Black hole search will require much effort
Matt Caplan, an associate professor of physics at Illinois State University who was not involved in the study, said the MIT team is just starting the real work:
It’s a very neat test they’ve proposed, and it could tell us if the closest black hole is closer than we realize. I should emphasize there’s a little bit of luck involved too. Whether or not a search finds a loud and clear signal depends on the exact path a wandering black hole takes through the solar system. Now that they’ve checked this idea with simulations, they have to do the hard part: checking the real data.
Bottom line: MIT researchers believe dark matter exists in the form of tiny black holes. Those black holes may cause Mars’ orbit to wobble, making them detectable.
View larger. | Martian ‘spiders‘ in the south polar region. NASA’s Mars Reconnaissance Orbiter (MRO) took this photo on August 23, 2009. Carbon dioxide gas escaping from beneath layers of ice carved the shapes into the terrain. Image via NASA/ JPL-Caltech/ University of Arizona.
Martian “spiders” are unusual geologic formations. Spacecraft have spotted the spiders in Mars’ south polar regions. They resemble giant spiders with many branching “legs.” How do they form?
Scientists have now recreated the processes involved in a laboratory for the first time. The results seem to confirm the carbon dioxide theory of how the spiders form.
Carbon dioxide gas erupts though cracks in overlaying ice layers. The gas plumes carry dust and soil, which fall to the surface and carve out the spider-like shapes in the ground.
The source of Martian ‘spiders’
Did you know there are spiders on Mars? But unlike their earthly counterparts, these are geologic formations. Scientists say they are caused by bursts of carbon dioxide gas escaping from beneath layers of ice. The gas – mixed with dark dust and sand – carves out the spider-like shapes in the ground. On September 11, 2024, a team of NASA scientists said it recreated the spiders in a lab for the first time. They duplicated the processes involved under simulated Martian conditions and successfully created formations that resemble those on Mars.
The researchers published their peer-reviewed study in The Planetary Science Journal on September 11.
The ‘spiders’ of Mars
The Martian “spiders” have intrigued scientists ever since they were first discovered in 2003. Basically, they are cracks in the terrain resembling the long legs of spiders, sometimes filled with carbon dioxide ice. Often they are in clusters, and they typically range from about 150 feet (45 meters) to 1/2 mile (almost 1 km) in size. And truly, they do look like giant spiders crawling across the landscape!
But their origin is geological, not biological. The leading theory has been that they form when carbon dioxide gas bursts in geyser-like jets to the surface from beneath a layer of carbon dioxide ice. The ice layers are transparent, and sunlight can heat the soil below them. Since the soil is darker, it absorbs the heat.
The ice adjacent to the warming soil doesn’t melt, it sublimates. That is, it turns directly into a gas. The gas creates pressure and eventually the ice starts to crack. The gas can then escape, and it takes dark dust and soil with it as it bursts into the atmosphere. The blowing dust and sand fall onto the Martian surface and help carve out the spider-like cracks in the ground. Notably, the paper said the cracks form within the soil, instead of just from scouring on the surface. The shapes are also still visible as scars on the surface after the rest of the ice sublimates in the warmer spring.
The sprawling spiders are a uniquely Martian phenomenon. Lead author Lauren Mc Keown at NASA’s Jet Propulsion Laboratory in California said:
The spiders are strange, beautiful geologic features in their own right. These experiments will help tune our models for how they form.
Testing how the Martian ‘spiders’ form
The researchers wanted to test the widely accepted theory that carbon dioxide gas creates the spiders. They based the tests on what is called the Kieffer model. The paper explained:
The Kieffer model is a widely accepted explanation for seasonal modification of the Martian surface by CO2 ice sublimation and the formation of a “zoo” of intriguing surface features. However, the lack of in situ observations and empirical laboratory measurements of Martian winter conditions hampers model validation and refinement.
View larger. | View inside the DUSTIE chamber, where the researchers simulated Martian surface conditions. Image via NASA/ JPL-Caltech.
DUSTIE
Part of the experiments involved re-creating Martian surface conditions. This included the very low air pressure – less than 1% of Earth’s at sea level – and temperatures as low as -301 degrees Fahrenheit (-185 C). The researchers used a liquid-nitrogen test chamber about the size of a wine barrel called DUSTIE (Dirty Under-vacuum Simulation Testbed for Icy Environments). Mc Keown said:
I love DUSTIE. It’s historic.
Previously, scientists had used DUSTIE to test a prototype of a rasping tool for the Mars Phoenix lander. Phoenix landed near the Martian north polar region in 2008.
The researchers created a Martian soil simulant, about 0.8 inches (2 cm) thick, for the tests. They placed it in a container that was then submerged in a cold liquid nitrogen bath. Next, they placed it in the DUSTIE chamber. The air pressure in the chamber was calibrated to be similar to that in Mars’ southern hemisphere.
Lastly, the research team pumped carbon dioxide gas into the chamber. In only three to five hours, it condensed into ice.
The researchers had to repeat the experiment multiple times to get the simulated conditions just right. Once they did, they placed a heater beneath the ice to warm it.
In this video, a small plume of carbon dioxide gas erupts from the simulated Martian soil, creating a hole in the process. Video via NASA/ JPL-Caltech.
View larger. | These cracks appeared in the simulated Martian soil inside the DUSTIE chamber. The effect, caused by the carbon dioxide gas, is similar to how scientists say the Martian “spiders” form. Image via NASA/ JPL-Caltech.
Recreating Martian ‘spiders’
And then it happened. The ice started to crack, and a plume of carbon dioxide gas vented from the simulated soil. It was a happy surprise for the scientists, who had been trying to do this for five years. As Mc Keown stated:
It was late on a Friday evening and the lab manager burst in after hearing me shrieking. She thought there had been an accident.
The plumes of gas created holes in the simulated soil, depositing some of the darker soil around them, just like what happens on Mars. This continued until all of the gas was released, taking about 10 minutes overall.
The researchers also observed something else unexpected. Ice formed between the grains of the simulated soil. This had the effect of “cracking” the soil. This seemed to depend, however, on how big the grains were and how deep ice was embedded in the soil. Study co-author Serina Diniega, also at the Jet Propulsion Laboratory, said:
It’s one of those details that show that nature is a little messier than the textbook image.
Future testing
The researchers will continue doing additional tests as well. They want to try heating the soil just beneath the ice using simulated sunlight instead of a heater. That will help them pinpoint just what conditions are necessary for the spiders to form on Mars. It will also help answer lingering questions. Why don’t the spiders grow in size and number over time? Why are they only in some locations on the planet and not others?
Another recent study showed Mars’ two polar ice caps differ from each other. This includes visually striking “fans” of dark dust that form as the dust and soil are blown out from spider formations by winds in the south polar region.
Bottom line: NASA scientists say they have confirmed a theory about how Martian ‘spiders’ form in the southern polar regions: erupting bursts of carbon dioxide gas.
View larger. | Martian ‘spiders‘ in the south polar region. NASA’s Mars Reconnaissance Orbiter (MRO) took this photo on August 23, 2009. Carbon dioxide gas escaping from beneath layers of ice carved the shapes into the terrain. Image via NASA/ JPL-Caltech/ University of Arizona.
Martian “spiders” are unusual geologic formations. Spacecraft have spotted the spiders in Mars’ south polar regions. They resemble giant spiders with many branching “legs.” How do they form?
Scientists have now recreated the processes involved in a laboratory for the first time. The results seem to confirm the carbon dioxide theory of how the spiders form.
Carbon dioxide gas erupts though cracks in overlaying ice layers. The gas plumes carry dust and soil, which fall to the surface and carve out the spider-like shapes in the ground.
The source of Martian ‘spiders’
Did you know there are spiders on Mars? But unlike their earthly counterparts, these are geologic formations. Scientists say they are caused by bursts of carbon dioxide gas escaping from beneath layers of ice. The gas – mixed with dark dust and sand – carves out the spider-like shapes in the ground. On September 11, 2024, a team of NASA scientists said it recreated the spiders in a lab for the first time. They duplicated the processes involved under simulated Martian conditions and successfully created formations that resemble those on Mars.
The researchers published their peer-reviewed study in The Planetary Science Journal on September 11.
The ‘spiders’ of Mars
The Martian “spiders” have intrigued scientists ever since they were first discovered in 2003. Basically, they are cracks in the terrain resembling the long legs of spiders, sometimes filled with carbon dioxide ice. Often they are in clusters, and they typically range from about 150 feet (45 meters) to 1/2 mile (almost 1 km) in size. And truly, they do look like giant spiders crawling across the landscape!
But their origin is geological, not biological. The leading theory has been that they form when carbon dioxide gas bursts in geyser-like jets to the surface from beneath a layer of carbon dioxide ice. The ice layers are transparent, and sunlight can heat the soil below them. Since the soil is darker, it absorbs the heat.
The ice adjacent to the warming soil doesn’t melt, it sublimates. That is, it turns directly into a gas. The gas creates pressure and eventually the ice starts to crack. The gas can then escape, and it takes dark dust and soil with it as it bursts into the atmosphere. The blowing dust and sand fall onto the Martian surface and help carve out the spider-like cracks in the ground. Notably, the paper said the cracks form within the soil, instead of just from scouring on the surface. The shapes are also still visible as scars on the surface after the rest of the ice sublimates in the warmer spring.
The sprawling spiders are a uniquely Martian phenomenon. Lead author Lauren Mc Keown at NASA’s Jet Propulsion Laboratory in California said:
The spiders are strange, beautiful geologic features in their own right. These experiments will help tune our models for how they form.
Testing how the Martian ‘spiders’ form
The researchers wanted to test the widely accepted theory that carbon dioxide gas creates the spiders. They based the tests on what is called the Kieffer model. The paper explained:
The Kieffer model is a widely accepted explanation for seasonal modification of the Martian surface by CO2 ice sublimation and the formation of a “zoo” of intriguing surface features. However, the lack of in situ observations and empirical laboratory measurements of Martian winter conditions hampers model validation and refinement.
View larger. | View inside the DUSTIE chamber, where the researchers simulated Martian surface conditions. Image via NASA/ JPL-Caltech.
DUSTIE
Part of the experiments involved re-creating Martian surface conditions. This included the very low air pressure – less than 1% of Earth’s at sea level – and temperatures as low as -301 degrees Fahrenheit (-185 C). The researchers used a liquid-nitrogen test chamber about the size of a wine barrel called DUSTIE (Dirty Under-vacuum Simulation Testbed for Icy Environments). Mc Keown said:
I love DUSTIE. It’s historic.
Previously, scientists had used DUSTIE to test a prototype of a rasping tool for the Mars Phoenix lander. Phoenix landed near the Martian north polar region in 2008.
The researchers created a Martian soil simulant, about 0.8 inches (2 cm) thick, for the tests. They placed it in a container that was then submerged in a cold liquid nitrogen bath. Next, they placed it in the DUSTIE chamber. The air pressure in the chamber was calibrated to be similar to that in Mars’ southern hemisphere.
Lastly, the research team pumped carbon dioxide gas into the chamber. In only three to five hours, it condensed into ice.
The researchers had to repeat the experiment multiple times to get the simulated conditions just right. Once they did, they placed a heater beneath the ice to warm it.
In this video, a small plume of carbon dioxide gas erupts from the simulated Martian soil, creating a hole in the process. Video via NASA/ JPL-Caltech.
View larger. | These cracks appeared in the simulated Martian soil inside the DUSTIE chamber. The effect, caused by the carbon dioxide gas, is similar to how scientists say the Martian “spiders” form. Image via NASA/ JPL-Caltech.
Recreating Martian ‘spiders’
And then it happened. The ice started to crack, and a plume of carbon dioxide gas vented from the simulated soil. It was a happy surprise for the scientists, who had been trying to do this for five years. As Mc Keown stated:
It was late on a Friday evening and the lab manager burst in after hearing me shrieking. She thought there had been an accident.
The plumes of gas created holes in the simulated soil, depositing some of the darker soil around them, just like what happens on Mars. This continued until all of the gas was released, taking about 10 minutes overall.
The researchers also observed something else unexpected. Ice formed between the grains of the simulated soil. This had the effect of “cracking” the soil. This seemed to depend, however, on how big the grains were and how deep ice was embedded in the soil. Study co-author Serina Diniega, also at the Jet Propulsion Laboratory, said:
It’s one of those details that show that nature is a little messier than the textbook image.
Future testing
The researchers will continue doing additional tests as well. They want to try heating the soil just beneath the ice using simulated sunlight instead of a heater. That will help them pinpoint just what conditions are necessary for the spiders to form on Mars. It will also help answer lingering questions. Why don’t the spiders grow in size and number over time? Why are they only in some locations on the planet and not others?
Another recent study showed Mars’ two polar ice caps differ from each other. This includes visually striking “fans” of dark dust that form as the dust and soil are blown out from spider formations by winds in the south polar region.
Bottom line: NASA scientists say they have confirmed a theory about how Martian ‘spiders’ form in the southern polar regions: erupting bursts of carbon dioxide gas.
On the night of September 17-18, 2024, the Earth, the sun and the Super Harvest Moon will line up in space, causing a lunar eclipse. The eclipse will be far from total. At mid-eclipse, only 8% of the moon will lie in Earth’s dark shadow. Still, the EarthSky team – in cooperation with our friends at TimeandDate.com – will have fun watching the eclipse LIVE beginning at 8:45 p.m. CDT on September 17 (1:45 UTC on September 18). We’ll be talking about why this September full moon is a Super Harvest Moon, about how eclipses prove the Earth is round, and more. Join us for an eclipse watch party!
People in the Americas, parts of Antarctica, the western Indian Ocean, the Middle East, Africa, Europe, the Atlantic Ocean, and eastern Polynesia will see a shallow partial lunar eclipse overnight on September 17-18, 2024. The steady golden light near the eclipsed moon will be the planet Saturn.
The whole half of Earth facing the full moon – that is, the whole half of Earth that’s in nighttime – will see the lunar eclipse. Of course, lunar eclipses are safe to view with the unaided eye. Binoculars and telescopes aren’t required to view a lunar eclipse, but they do enhance the view.
At this eclipse, only a small fraction of the moon will enter Earth’s dark umbral shadow. For the most part, the September 17-18, 2024, lunar eclipse will appear as a penumbral eclipse of the moon. In other words, as the eclipse progresses, you should notice a dark shading on the moon (Earth’s penumbral shadow), followed by the barest of dark bites (Earth’s dark umbral shadow) taken from one edge of the moon.
And don’t forget Saturn! It’s the bright object near the moon on September 17-18.
View full map. | Map showing the areas of visibility for the September 17-18, 2024, partial lunar eclipse. Image via Dominic Ford from In-the-sky.org. Used with permission.
Partial lunar eclipse September 17-18, 2024
See below for local viewing times from select cities of the partial lunar eclipse.
Here are local times for select cities indicating when the partial lunar eclipse begins and when the greatest eclipse occurs. Times via timeanddate.com.
Check timeanddate.com for precise timing from your location.
When the lunar eclipse occurs worldwide
Penumbral eclipse begins at 0:41 UTC on September 18, 2024. Earth’s lighter penumbral shadow will begin crossing the moon’s face. You probably won’t notice it at first. But, as the eclipse progresses, you should see a subtle shading on the moon. Partial eclipse begins at 2:12 UTC on September 18, 2024. Now it’ll appear as if a tiny, but dark, bite is taken from one edge of the moon. Greatest eclipse at 2:44 UTC on September 18, 2024. Only a small portion of the moon – about 8% – will be eclipsed by Earth’s dark shadow. Partial eclipse ends at 3:16 UTC on September 18, 2024. Penumbral eclipse ends at 4:47 UTC on September 18, 2024.
Note: A bright “star” will appear near the eclipsed moon. It’s really a planet, Saturn.
View at EarthSky Community Photos. | Nikolaos Pantazis in Athens, Greece, captured these images on October 28, 2023. Nikolaos wrote: “A collage of tonight’s partial lunar eclipse. The photos were shot at hours UTC, 19:45, 20:00 and 20:15, from start to maximum cover by the Earth’s shadow.” Thank you, Nikolaos!
Visit timeanddate.com to get an exact timing of the eclipse from your location.
During a lunar eclipse, Earth’s shadow falls on the moon. So if the moon passes through the dark central shadow of Earth – the umbra – a partial or total lunar eclipse takes place. But if the moon only passes through the outer part of the shadow (the penumbra), a subtle penumbral eclipse occurs. Diagram via Fred Espenak’s Lunar Eclipses for Beginners. Used with permission.
Who can see lunar eclipses?
A full moon is up only at night. And a total lunar eclipse is visible from all parts of Earth that are experiencing night while the eclipse is taking place. But some will see the eclipse more clearly, or more thoroughly, than others, depending on location. For example, some will see it at moonrise or moonset, when the moon is low in the sky.
The constellation behind the partial lunar eclipse
The September 17-18, 2024, partial lunar eclipse occurs when the moon is in the constellation of Pisces the Fish.
Find the moon’s path with respect to Earth’s umbral and penumbral shadows below.
A map for the partial lunar eclipse on September 17-18, 2024. It sweeps across the Americas, parts of Antarctica, the western Indian Ocean, the Middle East, Africa, Europe, the Atlantic Ocean, and eastern Polynesia. Areas in white on the map will see all of the partial eclipse. The line down the middle notes where the greatest eclipse occurs. Shaded areas will see part of the eclipse and dark areas are where the eclipse is not visible. Note the difference between UTC and TD (terrestrial dynamical time, often abbreviated TT as well). Key to lunar eclipse maps here. Image via Fred Espenak/ EclipseWise. Used with permission.
Bottom line: A shallow partial lunar eclipse takes place on September 17-18, 2024, visible in the Americas, parts of Antarctica, the western Indian Ocean, the Middle East, Africa, Europe, the Atlantic Ocean, and eastern Polynesia. Saturn is the bright light nearby. Maps and details here.
On the night of September 17-18, 2024, the Earth, the sun and the Super Harvest Moon will line up in space, causing a lunar eclipse. The eclipse will be far from total. At mid-eclipse, only 8% of the moon will lie in Earth’s dark shadow. Still, the EarthSky team – in cooperation with our friends at TimeandDate.com – will have fun watching the eclipse LIVE beginning at 8:45 p.m. CDT on September 17 (1:45 UTC on September 18). We’ll be talking about why this September full moon is a Super Harvest Moon, about how eclipses prove the Earth is round, and more. Join us for an eclipse watch party!
People in the Americas, parts of Antarctica, the western Indian Ocean, the Middle East, Africa, Europe, the Atlantic Ocean, and eastern Polynesia will see a shallow partial lunar eclipse overnight on September 17-18, 2024. The steady golden light near the eclipsed moon will be the planet Saturn.
The whole half of Earth facing the full moon – that is, the whole half of Earth that’s in nighttime – will see the lunar eclipse. Of course, lunar eclipses are safe to view with the unaided eye. Binoculars and telescopes aren’t required to view a lunar eclipse, but they do enhance the view.
At this eclipse, only a small fraction of the moon will enter Earth’s dark umbral shadow. For the most part, the September 17-18, 2024, lunar eclipse will appear as a penumbral eclipse of the moon. In other words, as the eclipse progresses, you should notice a dark shading on the moon (Earth’s penumbral shadow), followed by the barest of dark bites (Earth’s dark umbral shadow) taken from one edge of the moon.
And don’t forget Saturn! It’s the bright object near the moon on September 17-18.
View full map. | Map showing the areas of visibility for the September 17-18, 2024, partial lunar eclipse. Image via Dominic Ford from In-the-sky.org. Used with permission.
Partial lunar eclipse September 17-18, 2024
See below for local viewing times from select cities of the partial lunar eclipse.
Here are local times for select cities indicating when the partial lunar eclipse begins and when the greatest eclipse occurs. Times via timeanddate.com.
Check timeanddate.com for precise timing from your location.
When the lunar eclipse occurs worldwide
Penumbral eclipse begins at 0:41 UTC on September 18, 2024. Earth’s lighter penumbral shadow will begin crossing the moon’s face. You probably won’t notice it at first. But, as the eclipse progresses, you should see a subtle shading on the moon. Partial eclipse begins at 2:12 UTC on September 18, 2024. Now it’ll appear as if a tiny, but dark, bite is taken from one edge of the moon. Greatest eclipse at 2:44 UTC on September 18, 2024. Only a small portion of the moon – about 8% – will be eclipsed by Earth’s dark shadow. Partial eclipse ends at 3:16 UTC on September 18, 2024. Penumbral eclipse ends at 4:47 UTC on September 18, 2024.
Note: A bright “star” will appear near the eclipsed moon. It’s really a planet, Saturn.
View at EarthSky Community Photos. | Nikolaos Pantazis in Athens, Greece, captured these images on October 28, 2023. Nikolaos wrote: “A collage of tonight’s partial lunar eclipse. The photos were shot at hours UTC, 19:45, 20:00 and 20:15, from start to maximum cover by the Earth’s shadow.” Thank you, Nikolaos!
Visit timeanddate.com to get an exact timing of the eclipse from your location.
During a lunar eclipse, Earth’s shadow falls on the moon. So if the moon passes through the dark central shadow of Earth – the umbra – a partial or total lunar eclipse takes place. But if the moon only passes through the outer part of the shadow (the penumbra), a subtle penumbral eclipse occurs. Diagram via Fred Espenak’s Lunar Eclipses for Beginners. Used with permission.
Who can see lunar eclipses?
A full moon is up only at night. And a total lunar eclipse is visible from all parts of Earth that are experiencing night while the eclipse is taking place. But some will see the eclipse more clearly, or more thoroughly, than others, depending on location. For example, some will see it at moonrise or moonset, when the moon is low in the sky.
The constellation behind the partial lunar eclipse
The September 17-18, 2024, partial lunar eclipse occurs when the moon is in the constellation of Pisces the Fish.
Find the moon’s path with respect to Earth’s umbral and penumbral shadows below.
A map for the partial lunar eclipse on September 17-18, 2024. It sweeps across the Americas, parts of Antarctica, the western Indian Ocean, the Middle East, Africa, Europe, the Atlantic Ocean, and eastern Polynesia. Areas in white on the map will see all of the partial eclipse. The line down the middle notes where the greatest eclipse occurs. Shaded areas will see part of the eclipse and dark areas are where the eclipse is not visible. Note the difference between UTC and TD (terrestrial dynamical time, often abbreviated TT as well). Key to lunar eclipse maps here. Image via Fred Espenak/ EclipseWise. Used with permission.
Bottom line: A shallow partial lunar eclipse takes place on September 17-18, 2024, visible in the Americas, parts of Antarctica, the western Indian Ocean, the Middle East, Africa, Europe, the Atlantic Ocean, and eastern Polynesia. Saturn is the bright light nearby. Maps and details here.
