The dog days of summer refer to the hottest days of the year that we experience in July and August. No, they aren’t named after dogs, our cute and furry friends. But they are named after the Dog Star – the brightest star in the sky – Sirius. It’s in the constellation of Canis Major, the Greater Dog. By the way, the Belt of Orion can point you to dazzling Sirius in the morning sky.
What are the dog days of summer?
You might have heard the hottest days of summer referred to as the “dog days of summer” … but where did this term come from? According to the National Weather Service:
The “dog days of summer” is a phrase used to describe the hot and humid days of summer. It can be traced back thousands of years to the days of the Roman Empire. It refers to the dates from July 3 through August 11, which is 20 days prior and 20 days after the star Sirius rises and falls in conjunction with the sun. Sirius was known as the “Dog Star,” because it is the brightest star in the constellation Canis Major (Large Dog).
So, you can see the term dog days isn’t new. And its origin is based on objects in the sky.
What does Sirius have to do with the hottest days of summer?
The fact is, the name Sirius comes from an ancient Greek word for “scorching” or “glowing.” Plus, Sirius is the brightest star visible from Earth, and it’s visible from both hemispheres. Also, it’s the brightest star in the evening sky during the Northern Hemisphere winter.
Sirius is behind the sun as seen from Earth during the Northern Hemisphere summer. Then, in late summer, it appears in the east before sunrise, near the sun in our sky.
Ancient Egyptians noted that Sirius rose just before the sun each year immediately prior to the annual flooding of the Nile River. Although the floods could bring destruction, they also brought new soil and new life.
Ancient Romans noticed the reappearance of Sirius in the morning sky as well. And they blamed it for the heat in July and August. That’s because Sirius rose each day before sunrise. And then, it traveled across the sky with the sun all day. Thus, early stargazers might have imagined a double-whammy from Sirius and the sun caused the hot weather.
Dog days and Sirius in conjunction with the sun
Since Sirius is in conjunction with the sun on July 23, the dog days of summer centered around then. The dog days of summer fall between July 3 to August 11, and that’s when we have our warmest days in the Northern Hemisphere.
So even though we know why this is the hottest time of the year in the Northern Hemisphere, the legend of the dog days has survived.
Bottom line: The dog days of summer are named for the Dog Star, Sirius – the brightest star in the sky – in the constellation Canis Major the Greater Dog.
The dog days of summer refer to the hottest days of the year that we experience in July and August. No, they aren’t named after dogs, our cute and furry friends. But they are named after the Dog Star – the brightest star in the sky – Sirius. It’s in the constellation of Canis Major, the Greater Dog. By the way, the Belt of Orion can point you to dazzling Sirius in the morning sky.
What are the dog days of summer?
You might have heard the hottest days of summer referred to as the “dog days of summer” … but where did this term come from? According to the National Weather Service:
The “dog days of summer” is a phrase used to describe the hot and humid days of summer. It can be traced back thousands of years to the days of the Roman Empire. It refers to the dates from July 3 through August 11, which is 20 days prior and 20 days after the star Sirius rises and falls in conjunction with the sun. Sirius was known as the “Dog Star,” because it is the brightest star in the constellation Canis Major (Large Dog).
So, you can see the term dog days isn’t new. And its origin is based on objects in the sky.
What does Sirius have to do with the hottest days of summer?
The fact is, the name Sirius comes from an ancient Greek word for “scorching” or “glowing.” Plus, Sirius is the brightest star visible from Earth, and it’s visible from both hemispheres. Also, it’s the brightest star in the evening sky during the Northern Hemisphere winter.
Sirius is behind the sun as seen from Earth during the Northern Hemisphere summer. Then, in late summer, it appears in the east before sunrise, near the sun in our sky.
Ancient Egyptians noted that Sirius rose just before the sun each year immediately prior to the annual flooding of the Nile River. Although the floods could bring destruction, they also brought new soil and new life.
Ancient Romans noticed the reappearance of Sirius in the morning sky as well. And they blamed it for the heat in July and August. That’s because Sirius rose each day before sunrise. And then, it traveled across the sky with the sun all day. Thus, early stargazers might have imagined a double-whammy from Sirius and the sun caused the hot weather.
Dog days and Sirius in conjunction with the sun
Since Sirius is in conjunction with the sun on July 23, the dog days of summer centered around then. The dog days of summer fall between July 3 to August 11, and that’s when we have our warmest days in the Northern Hemisphere.
So even though we know why this is the hottest time of the year in the Northern Hemisphere, the legend of the dog days has survived.
Bottom line: The dog days of summer are named for the Dog Star, Sirius – the brightest star in the sky – in the constellation Canis Major the Greater Dog.
View larger. | This Cassini image of Saturn’s ocean moon Enceladus is from October 9, 2008. A new study shows some ocean moons in our solar system could maintain hydrothermal activity on their ocean floors. The hydrothermal vents could be active for millions to billions of years and be able to support life. Image via NASA/ JPL/ Space Science Institute.
Researchers at UC Santa Cruz led a new study of possible hydrothermal vents on the seafloors of ocean moons in our solar system.
They simulated seafloor conditions on the moons by using models of hydrothermal activity in Earth’s oceans.
The researchers found such hydrothermal activity could exist on ocean moons for millions to billions of years and possibly support life.
Hydrothermal vents on ocean moons could support life
Hydrothermal vents are geyser-like jets of geothermally heated water on the ocean floor. They can be an oasis for a wide variety of deep-sea life forms despite the surrounding cold temperatures and lack of sunlight. Scientists have wondered if hydrothermal vents could exist on ocean moons in our solar system, such as Europa and Enceladus. On June 24, 2024, researchers said hydrothermal vents could be sustained under a wide range of conditions. And they also said the vents could be capable of supporting life.
In order to determine whether hydrothermal vents could be occurring on any of the ocean moons, the researchers used a complex computer model. The model is based on hydrothermal circulation on Earth. This is basically the circulation of hot water in the ocean. The study focused on the 3.5 million-year-old seafloor in the northwestern Pacific Ocean, east of the Juan de Fuca Ridge. But ocean moons are not the same as Earth, even though they have lots of water. So the researchers had to take into account differences such as gravity, heat, rock properties and fluid-circulation depth.
The researchers found similar hydrothermal vents could indeed exist on ocean moons. They could even be sustained under a wide variety of conditions. They would be of relatively lower temperature, so not too hot for life to exist. The study results showed this hydrothermal activity could continue for millions to billions of years, possibly throughout the life of the solar system and long enough for life to start. As Andrew Fisher, the lead author from UC Santa Cruz, said:
This study suggests that low temperature (not too hot for life) hydrothermal systems could have been sustained on ocean worlds beyond Earth over timescales comparable to that required for life to take hold on Earth.
View larger. | Graphic depicting hydrothermal activity on the ocean floor of Enceladus. Image via NASA/ JPL-Caltech/ Southwest Research Institute.
Hydrothermal circulation
In the seafloor environment used in the study, cool bottom water flows in through an extinct volcano with steep sides (also called a seamount). Then, it travels underground for about 30 miles (about 50 km) and flows back out into the ocean through another seamount. Co-author Kristin Dickerson at UC Santa Cruz noted:
The water gathers heat as it flows and comes out warmer than when it flowed in, and with very different chemistry.
Buoyancy enables the flow of hot water, called hydrothermal circulation, between the seamounts. This is due to water being less dense when it warms and more dense when it cools. So it creates differences in fluid pressure in the seafloor rock. As such, the system is self-sustaining. Fisher said:
It’s even possible this kind of hydrothermal vent could be more likely on ocean moons than on Earth. Co-author Donna Blackman said:
Lower-temperature flows are at least as likely to occur, if not more likely.
View larger. | A black smoker hydrothermal vent on the seafloor of the Atlantic Ocean. Image via P. Rona/ OAR/ National Undersea Research Program (NURP)/ NOAA/ NOAA Photo Library/ Wikimedia Commons (public domain).
Previous evidence for hydrothermal vents on Enceladus
There has, in fact, already been some previous evidence found for hydrothermal activity on Saturn’s moon Enceladus.
Earlier studies of data from NASA’s Cassini spacecraft showed the presence of both molecular hydrogen and silica in the water vapor plumes that originate from Enceladus’ subsurface ocean. Both are markers of hydrothermal activity on the ocean floor.
As Hunter Waite of the Southwest Research Institute (SwRI) and principal investigator of Cassini’s Ion Neutral Mass Spectrometer (INMS) said at the time:
The dynamic interface of a complex core and seawater could potentially create energy sources that might support life. While we have not found evidence of the presence of microbial life in the ocean of Enceladus, the growing evidence for chemical disequilibrium offers a tantalizing hint that habitable conditions could exist beneath the moon’s icy crust.
Even if there are hydrothermal vents on ocean moons, that doesn’t prove life is there. But it does add to a growing list of evidence for habitable conditions in at least some of these alien oceans. This includes Jupiter’s moon Europa in particular, which is now thought to also have possible hydrothermal vents.
Bottom line: A new study shows ocean moons in our solar system could have long-lasting geothermal activity on their oceans floors and may even be able to support life.
View larger. | This Cassini image of Saturn’s ocean moon Enceladus is from October 9, 2008. A new study shows some ocean moons in our solar system could maintain hydrothermal activity on their ocean floors. The hydrothermal vents could be active for millions to billions of years and be able to support life. Image via NASA/ JPL/ Space Science Institute.
Researchers at UC Santa Cruz led a new study of possible hydrothermal vents on the seafloors of ocean moons in our solar system.
They simulated seafloor conditions on the moons by using models of hydrothermal activity in Earth’s oceans.
The researchers found such hydrothermal activity could exist on ocean moons for millions to billions of years and possibly support life.
Hydrothermal vents on ocean moons could support life
Hydrothermal vents are geyser-like jets of geothermally heated water on the ocean floor. They can be an oasis for a wide variety of deep-sea life forms despite the surrounding cold temperatures and lack of sunlight. Scientists have wondered if hydrothermal vents could exist on ocean moons in our solar system, such as Europa and Enceladus. On June 24, 2024, researchers said hydrothermal vents could be sustained under a wide range of conditions. And they also said the vents could be capable of supporting life.
In order to determine whether hydrothermal vents could be occurring on any of the ocean moons, the researchers used a complex computer model. The model is based on hydrothermal circulation on Earth. This is basically the circulation of hot water in the ocean. The study focused on the 3.5 million-year-old seafloor in the northwestern Pacific Ocean, east of the Juan de Fuca Ridge. But ocean moons are not the same as Earth, even though they have lots of water. So the researchers had to take into account differences such as gravity, heat, rock properties and fluid-circulation depth.
The researchers found similar hydrothermal vents could indeed exist on ocean moons. They could even be sustained under a wide variety of conditions. They would be of relatively lower temperature, so not too hot for life to exist. The study results showed this hydrothermal activity could continue for millions to billions of years, possibly throughout the life of the solar system and long enough for life to start. As Andrew Fisher, the lead author from UC Santa Cruz, said:
This study suggests that low temperature (not too hot for life) hydrothermal systems could have been sustained on ocean worlds beyond Earth over timescales comparable to that required for life to take hold on Earth.
View larger. | Graphic depicting hydrothermal activity on the ocean floor of Enceladus. Image via NASA/ JPL-Caltech/ Southwest Research Institute.
Hydrothermal circulation
In the seafloor environment used in the study, cool bottom water flows in through an extinct volcano with steep sides (also called a seamount). Then, it travels underground for about 30 miles (about 50 km) and flows back out into the ocean through another seamount. Co-author Kristin Dickerson at UC Santa Cruz noted:
The water gathers heat as it flows and comes out warmer than when it flowed in, and with very different chemistry.
Buoyancy enables the flow of hot water, called hydrothermal circulation, between the seamounts. This is due to water being less dense when it warms and more dense when it cools. So it creates differences in fluid pressure in the seafloor rock. As such, the system is self-sustaining. Fisher said:
It’s even possible this kind of hydrothermal vent could be more likely on ocean moons than on Earth. Co-author Donna Blackman said:
Lower-temperature flows are at least as likely to occur, if not more likely.
View larger. | A black smoker hydrothermal vent on the seafloor of the Atlantic Ocean. Image via P. Rona/ OAR/ National Undersea Research Program (NURP)/ NOAA/ NOAA Photo Library/ Wikimedia Commons (public domain).
Previous evidence for hydrothermal vents on Enceladus
There has, in fact, already been some previous evidence found for hydrothermal activity on Saturn’s moon Enceladus.
Earlier studies of data from NASA’s Cassini spacecraft showed the presence of both molecular hydrogen and silica in the water vapor plumes that originate from Enceladus’ subsurface ocean. Both are markers of hydrothermal activity on the ocean floor.
As Hunter Waite of the Southwest Research Institute (SwRI) and principal investigator of Cassini’s Ion Neutral Mass Spectrometer (INMS) said at the time:
The dynamic interface of a complex core and seawater could potentially create energy sources that might support life. While we have not found evidence of the presence of microbial life in the ocean of Enceladus, the growing evidence for chemical disequilibrium offers a tantalizing hint that habitable conditions could exist beneath the moon’s icy crust.
Even if there are hydrothermal vents on ocean moons, that doesn’t prove life is there. But it does add to a growing list of evidence for habitable conditions in at least some of these alien oceans. This includes Jupiter’s moon Europa in particular, which is now thought to also have possible hydrothermal vents.
Bottom line: A new study shows ocean moons in our solar system could have long-lasting geothermal activity on their oceans floors and may even be able to support life.
Albireo, also known as Beta Cygni, is the 2nd-brightest star in the constellation Cygnus the Swan. At first glance, it doesn’t particularly stand out. But viewing this star through a small telescope can take your breath away. It resolves into a striking double, with one component a lovely gold star and the other a dimmer blue close by.
From our perspective, the two stars appear close in the sky, but it’s unknown if they’re gravitationally bound to each other. Regardless, the color contrast between the two is so striking that Albireo is one of the most beautiful double stars in the heavens.
The Summer Triangle can help you find Albireo. Albireo is inside the Summer Triangle, at the foot of the Northern Cross, or Cygnus.
How to find Albireo
How can you spot Albireo in the night sky? It’s easy to find, if you can locate Cygnus the Swan. Cygnus has an easy-to-recognize shape, that of a cross. The constellation is also known as the asterism of the Northern Cross. The brightest star in Cygnus – Deneb – marks the head of the Cross or the Tail of the Swan. Albireo marks the base of the Cross or the Head of Cygnus.
And how can you see Albireo as two stars? They’re best viewed at 30X (“30 power” or a magnification of 30). Unless you have exceedingly powerful binoculars, mounted on a tripod, binoculars won’t show you Albireo as two stars. But any small telescope will. When you see Albireo as two stars, be sure to notice the striking color contrast between the two.
The brighter, golden star – Albireo A – is about 420 light-years away. Albireo B, the dimmer blue star, is around 400 light-years distant. Although this is not confirmed, Albireo A and B are most likely an optical double star and not a physical binary system.
On the other hand, Albireo A is a binary star, with two stars so close together that you can’t see them as separate. The Albireo A binary star system has an orbital period of 121.6 years. The brighter star is responsible for the gold color you see through a telescope. It’s a red supergiant star, about 5 times the mass of the sun. It shines at magnitude 3.21. And it outshines its fainter companion, a hot main sequence star that’s 2.7 times the sun’s mass.
Furthermore, in a recent analysis of the Albireo A binary system, astronomers were surprised to find that there may be more stars in the system, possibly making Albireo A a triple or quadruple star system.
Albireo B, the fainter blue star of the pair when viewed through a small telescope, appears just 34 arc seconds away from gold-colored Albireo A. It’s a hot blue star, about 3.7 times the sun’s mass. It shines at magnitude 5.11. If it is a physical companion star to Albireo A, their orbital period would take about 100,000 years.
Bottom line: Albireo, in the constellation Cygnus, is a favorite for stargazers. Through a small telescope, it appears as a beautiful golden star with a dimmer blue companion.
Albireo, also known as Beta Cygni, is the 2nd-brightest star in the constellation Cygnus the Swan. At first glance, it doesn’t particularly stand out. But viewing this star through a small telescope can take your breath away. It resolves into a striking double, with one component a lovely gold star and the other a dimmer blue close by.
From our perspective, the two stars appear close in the sky, but it’s unknown if they’re gravitationally bound to each other. Regardless, the color contrast between the two is so striking that Albireo is one of the most beautiful double stars in the heavens.
The Summer Triangle can help you find Albireo. Albireo is inside the Summer Triangle, at the foot of the Northern Cross, or Cygnus.
How to find Albireo
How can you spot Albireo in the night sky? It’s easy to find, if you can locate Cygnus the Swan. Cygnus has an easy-to-recognize shape, that of a cross. The constellation is also known as the asterism of the Northern Cross. The brightest star in Cygnus – Deneb – marks the head of the Cross or the Tail of the Swan. Albireo marks the base of the Cross or the Head of Cygnus.
And how can you see Albireo as two stars? They’re best viewed at 30X (“30 power” or a magnification of 30). Unless you have exceedingly powerful binoculars, mounted on a tripod, binoculars won’t show you Albireo as two stars. But any small telescope will. When you see Albireo as two stars, be sure to notice the striking color contrast between the two.
The brighter, golden star – Albireo A – is about 420 light-years away. Albireo B, the dimmer blue star, is around 400 light-years distant. Although this is not confirmed, Albireo A and B are most likely an optical double star and not a physical binary system.
On the other hand, Albireo A is a binary star, with two stars so close together that you can’t see them as separate. The Albireo A binary star system has an orbital period of 121.6 years. The brighter star is responsible for the gold color you see through a telescope. It’s a red supergiant star, about 5 times the mass of the sun. It shines at magnitude 3.21. And it outshines its fainter companion, a hot main sequence star that’s 2.7 times the sun’s mass.
Furthermore, in a recent analysis of the Albireo A binary system, astronomers were surprised to find that there may be more stars in the system, possibly making Albireo A a triple or quadruple star system.
Albireo B, the fainter blue star of the pair when viewed through a small telescope, appears just 34 arc seconds away from gold-colored Albireo A. It’s a hot blue star, about 3.7 times the sun’s mass. It shines at magnitude 5.11. If it is a physical companion star to Albireo A, their orbital period would take about 100,000 years.
Bottom line: Albireo, in the constellation Cygnus, is a favorite for stargazers. Through a small telescope, it appears as a beautiful golden star with a dimmer blue companion.
Hurricane Beryl on July 2, 2024. Image via NOAA/ GOES.
Beryl formed farther east than any other June hurricane since the mid-1800s, when record-keeping began.
It moved from tropical depression status into a Category 3 hurricane in less than 48 hours, something that’s never happened before earlier than September (since record-keeping began).
Overall, Hurricane Beryl became the strongest Atlantic hurricane on record for June, beating out Hurricane Audrey in 1957.
The Atlantic Basin usually doesn’t see its first major hurricane until around September 1. But, as its wind gusted to 160 mph overnight last night (July 1, 2024), Beryl became the earliest Category 5 hurricane on record. Experts say Beryl has been super-charged by warm seas.
And, as of Tuesday morning, July 2, Beryl was continuing its westward sweep through the Atlantic Basin. AP reported:
Hurricane Beryl strengthened to Category 5 status late Monday after it ripped doors, windows and roofs off homes across the southeastern Caribbean with devastating winds and storm surge fueled by the Atlantic’s record warmth.
Beryl made landfall on the island of Carriacou in Grenada as the earliest Category 4 storm in the Atlantic, then late in the day the National Hurricane Center in Miami said its winds had increased to Category 5 strength. Fluctuations in strength, and later a significant weakening, were forecast as the storm pushes further into the Caribbean in the coming days.
Beryl is headed toward the east coast of Mexico. If it continues on its current course, it should make another landfall on Sunday morning.
Forecast potential path of Hurricane Beryl as of Tuesday morning at 5 a.m. Map via NOAA’s National Hurricane Center.Hurricane Beryl on July 1, 2024. Image via NOAA/ USAToday.
Bottom line: Hurricane Beryl had gusts of up to 160 mph last night, giving it Category 5 hurricane status and making it the earliest Category 5 storm on record.
Hurricane Beryl on July 2, 2024. Image via NOAA/ GOES.
Beryl formed farther east than any other June hurricane since the mid-1800s, when record-keeping began.
It moved from tropical depression status into a Category 3 hurricane in less than 48 hours, something that’s never happened before earlier than September (since record-keeping began).
Overall, Hurricane Beryl became the strongest Atlantic hurricane on record for June, beating out Hurricane Audrey in 1957.
The Atlantic Basin usually doesn’t see its first major hurricane until around September 1. But, as its wind gusted to 160 mph overnight last night (July 1, 2024), Beryl became the earliest Category 5 hurricane on record. Experts say Beryl has been super-charged by warm seas.
And, as of Tuesday morning, July 2, Beryl was continuing its westward sweep through the Atlantic Basin. AP reported:
Hurricane Beryl strengthened to Category 5 status late Monday after it ripped doors, windows and roofs off homes across the southeastern Caribbean with devastating winds and storm surge fueled by the Atlantic’s record warmth.
Beryl made landfall on the island of Carriacou in Grenada as the earliest Category 4 storm in the Atlantic, then late in the day the National Hurricane Center in Miami said its winds had increased to Category 5 strength. Fluctuations in strength, and later a significant weakening, were forecast as the storm pushes further into the Caribbean in the coming days.
Beryl is headed toward the east coast of Mexico. If it continues on its current course, it should make another landfall on Sunday morning.
Forecast potential path of Hurricane Beryl as of Tuesday morning at 5 a.m. Map via NOAA’s National Hurricane Center.Hurricane Beryl on July 1, 2024. Image via NOAA/ USAToday.
Bottom line: Hurricane Beryl had gusts of up to 160 mph last night, giving it Category 5 hurricane status and making it the earliest Category 5 storm on record.
View larger. | Jupiter and its Great Red Spot in near-infrared light from Webb, using its NIRCam instrument. ESA released the image on June 25, 2024. Image via ESA/ Webb/ NASA/ CSA, Jupiter ERS Team/ J. Schmidt/ H. Melin/ M. Zamani (ESA/ Webb).
The atmosphere above Jupiter’s Great Red Spot is active and dynamic. That’s according to astronomers who observed it with the James Webb Space Telescope, who expected it to be calmer.
Webb found a surprising amount of activity, including dark arcs and bright spots across the whole field of view of the telescope.
Gravity waves in the atmosphere may be creating the unexpected amount of complexity in the region above the Great Red Spot.
Jupiter’s Great Red Spot has surprises
Jupiter’s Great Red Spot is a 190-year-old storm larger than Earth. Yet scientists thought the atmosphere above the storm was rather benign and uneventful. But on June 24, 2025, astronomers said they used NASA’s James Webb Space Telescope to discover the region is not as bland as expected. In fact, they found a variety of previously unseen atmospheric shapes and structures.
The international team of researchers published their peer-reviewed findings in Nature Astronomy on June 21, 2024.
Observing the region above Jupiter’s Great Red Spot
The Great Red Spot is a massive storm on Jupiter that swirls in a counterclockwise motion. It’s a turbulent and chaotic place, to be sure. But scientists thought the upper atmosphere directly above the spot was much calmer, almost boring, even. They thought the atmosphere in this region would be more homogenous, due to the fact that Jupiter receives only 4% of the sunlight Earth does. Therefore, there should be a lot less influence on the atmosphere by sunlight.
There are, however, bright auroras at Jupiter’s poles. These auroras are the result of volcanic material from Jupiter’s moon Io hitting the planet’s magnetic field just above the upper atmosphere.
The researchers wanted to take a closer look at the region just above the Great Red Spot. They used the Near-InfraRed Spectrograph (NIRSpec) on Webb for the observations in July 2022. The research team focused on the atmosphere over the Great Red Spot.
To their surprise, this region turned out to be much more active than anticipated. Webb revealed dark arcs and bright spots across the entire field of view. Lead author Henrik Melin at the University of Leicester in the U.K. said:
We thought this region, perhaps naively, would be really boring. It is in fact just as interesting as the northern lights, if not more so. Jupiter never ceases to surprise.
Here, we present James Webb Space Telescope H3+ observations of Jupiter’s low-latitude ionosphere in the region of the Great Red Spot, showing unexpected small-scale intensity features such as arcs, bands and spots. Our observations may imply that the low-latitude ionosphere of Jupiter is strongly coupled to the lower atmosphere via gravity waves that superimpose to produce this complex and intricate morphology.
View larger. | Near-infrared view of Jupiter’s Great Red Spot (large oval) from Webb’s Near-InfraRed Spectrograph (NIRSpec). The image is a composite of 6 NIRSpec Integral Field Unit images from July 2022. Image via ESA/ Webb/ NASA/ CSA/ H. Melin/ M. Zamani (ESA/Webb).
Why is this region above the Great Red Spot so active?
The researchers said sunlight alone can’t explain why the atmosphere above the Great Red Spot is so much more active than previously thought. One answer might be gravity waves. Melin explained:
One way in which you can change this structure is by gravity waves, similar to waves crashing on a beach, creating ripples in the sand. These waves are generated deep in the turbulent lower atmosphere, all around the Great Red Spot, and they can travel up in altitude, changing the structure and emissions of the upper atmosphere.
The researchers plan to do more follow-up observations to see how the arcs and spots move and change over time. You can see similar waves in Earth’s atmosphere sometimes, but they’re much weaker than the possible ones on Jupiter.
Just days ago, another group of astronomers also said the Great Red Spot is probably only about 190 years old in its current form. So it’s not the same storm that astronomers first saw in the 1600s.
Juice mission
In July 2031, ESA’s Jupiter Icy Moons Explorer (Juice) will arrive at Jupiter. Juice will study Jupiter and three of its largest moons – Ganymede, Callisto and Europa – in incredible detail. It will be able to observe the Great Red Spot and atmosphere up close.
Bottom line: The Webb space telescope observed Jupiter’s Great Red Spot and found the atmosphere above the spot is much more active and dynamic than astronomers expected.
View larger. | Jupiter and its Great Red Spot in near-infrared light from Webb, using its NIRCam instrument. ESA released the image on June 25, 2024. Image via ESA/ Webb/ NASA/ CSA, Jupiter ERS Team/ J. Schmidt/ H. Melin/ M. Zamani (ESA/ Webb).
The atmosphere above Jupiter’s Great Red Spot is active and dynamic. That’s according to astronomers who observed it with the James Webb Space Telescope, who expected it to be calmer.
Webb found a surprising amount of activity, including dark arcs and bright spots across the whole field of view of the telescope.
Gravity waves in the atmosphere may be creating the unexpected amount of complexity in the region above the Great Red Spot.
Jupiter’s Great Red Spot has surprises
Jupiter’s Great Red Spot is a 190-year-old storm larger than Earth. Yet scientists thought the atmosphere above the storm was rather benign and uneventful. But on June 24, 2025, astronomers said they used NASA’s James Webb Space Telescope to discover the region is not as bland as expected. In fact, they found a variety of previously unseen atmospheric shapes and structures.
The international team of researchers published their peer-reviewed findings in Nature Astronomy on June 21, 2024.
Observing the region above Jupiter’s Great Red Spot
The Great Red Spot is a massive storm on Jupiter that swirls in a counterclockwise motion. It’s a turbulent and chaotic place, to be sure. But scientists thought the upper atmosphere directly above the spot was much calmer, almost boring, even. They thought the atmosphere in this region would be more homogenous, due to the fact that Jupiter receives only 4% of the sunlight Earth does. Therefore, there should be a lot less influence on the atmosphere by sunlight.
There are, however, bright auroras at Jupiter’s poles. These auroras are the result of volcanic material from Jupiter’s moon Io hitting the planet’s magnetic field just above the upper atmosphere.
The researchers wanted to take a closer look at the region just above the Great Red Spot. They used the Near-InfraRed Spectrograph (NIRSpec) on Webb for the observations in July 2022. The research team focused on the atmosphere over the Great Red Spot.
To their surprise, this region turned out to be much more active than anticipated. Webb revealed dark arcs and bright spots across the entire field of view. Lead author Henrik Melin at the University of Leicester in the U.K. said:
We thought this region, perhaps naively, would be really boring. It is in fact just as interesting as the northern lights, if not more so. Jupiter never ceases to surprise.
Here, we present James Webb Space Telescope H3+ observations of Jupiter’s low-latitude ionosphere in the region of the Great Red Spot, showing unexpected small-scale intensity features such as arcs, bands and spots. Our observations may imply that the low-latitude ionosphere of Jupiter is strongly coupled to the lower atmosphere via gravity waves that superimpose to produce this complex and intricate morphology.
View larger. | Near-infrared view of Jupiter’s Great Red Spot (large oval) from Webb’s Near-InfraRed Spectrograph (NIRSpec). The image is a composite of 6 NIRSpec Integral Field Unit images from July 2022. Image via ESA/ Webb/ NASA/ CSA/ H. Melin/ M. Zamani (ESA/Webb).
Why is this region above the Great Red Spot so active?
The researchers said sunlight alone can’t explain why the atmosphere above the Great Red Spot is so much more active than previously thought. One answer might be gravity waves. Melin explained:
One way in which you can change this structure is by gravity waves, similar to waves crashing on a beach, creating ripples in the sand. These waves are generated deep in the turbulent lower atmosphere, all around the Great Red Spot, and they can travel up in altitude, changing the structure and emissions of the upper atmosphere.
The researchers plan to do more follow-up observations to see how the arcs and spots move and change over time. You can see similar waves in Earth’s atmosphere sometimes, but they’re much weaker than the possible ones on Jupiter.
Just days ago, another group of astronomers also said the Great Red Spot is probably only about 190 years old in its current form. So it’s not the same storm that astronomers first saw in the 1600s.
Juice mission
In July 2031, ESA’s Jupiter Icy Moons Explorer (Juice) will arrive at Jupiter. Juice will study Jupiter and three of its largest moons – Ganymede, Callisto and Europa – in incredible detail. It will be able to observe the Great Red Spot and atmosphere up close.
Bottom line: The Webb space telescope observed Jupiter’s Great Red Spot and found the atmosphere above the spot is much more active and dynamic than astronomers expected.
On June 27, 2024, Falcon 9 launched 23 Starlink satellites into orbit from Florida. Image via SpaceX.
Upcoming SpaceX Starlink launches in July 2024
Starlink Group 8-9: July 3, 2024, 2:01 a.m. EDT
Falcon 9 Block 5 | Cape Canaveral Space Force Station, Florida | DATE/TIME MAY CHANGE
Starlink Group 9-3: July 6, 2024, 8:33 p.m. PDT
Falcon 9 Block 5 | Vandenberg Space Force Base, California | DATE/TIME MAY CHANGE
You can watch a livestream of the Starlink launches on SpaceX’s X account.
Watch this space for updates!
After launch, look for a train of lights
Following every Starlink launch, the internet buzzes with people asking:
What’s that long line of lights in the sky that looks like a train?
What you’re seeing is the Starlink satellites moving into a higher orbit. You can check to see if they will pass over your area using the Find Starlink website.
Growing numbers amid controversy
According to Wikipedia, as of early March 2024, Starlink consists of over 6,000 mass-produced small satellites in low Earth orbit that communicate with designated ground transceivers. They provide internet access to more than 2 million subscribers.
Love ’em or hate ’em, these Starlink satellites are part of SpaceX’s vision for a global internet communication satellite constellation. They deliver high-speed internet service worldwide, mainly to locations where ground-based internet is unreliable, unavailable or expensive. The private company is well-known for launching batches back-to-back, several times a month, regularly lofting up to 60 satellites at a time. And SpaceX plans to build up to perhaps as many as 30,000 eventually.
Most thought it was exciting to see the first few Starlink satellites traveling together in the night sky. But then more were launched, and then more. And astronomers began to worry.
Because Starlinks are bright, astronomers say they’re photobombing astronomical images. Therefore, they have the potential to interfere with the professional astronomical observations that have brought us our modern-day view of the cosmos. And although SpaceX has tried to address the issue, they remain far from what astronomers say is acceptable.
Bottom line: Get a list of all the SpaceX Starlink launches for July 2024 from both the West and East Coasts. Find out how to watch the livestream, and get updates, too.
On June 27, 2024, Falcon 9 launched 23 Starlink satellites into orbit from Florida. Image via SpaceX.
Upcoming SpaceX Starlink launches in July 2024
Starlink Group 8-9: July 3, 2024, 2:01 a.m. EDT
Falcon 9 Block 5 | Cape Canaveral Space Force Station, Florida | DATE/TIME MAY CHANGE
Starlink Group 9-3: July 6, 2024, 8:33 p.m. PDT
Falcon 9 Block 5 | Vandenberg Space Force Base, California | DATE/TIME MAY CHANGE
You can watch a livestream of the Starlink launches on SpaceX’s X account.
Watch this space for updates!
After launch, look for a train of lights
Following every Starlink launch, the internet buzzes with people asking:
What’s that long line of lights in the sky that looks like a train?
What you’re seeing is the Starlink satellites moving into a higher orbit. You can check to see if they will pass over your area using the Find Starlink website.
Growing numbers amid controversy
According to Wikipedia, as of early March 2024, Starlink consists of over 6,000 mass-produced small satellites in low Earth orbit that communicate with designated ground transceivers. They provide internet access to more than 2 million subscribers.
Love ’em or hate ’em, these Starlink satellites are part of SpaceX’s vision for a global internet communication satellite constellation. They deliver high-speed internet service worldwide, mainly to locations where ground-based internet is unreliable, unavailable or expensive. The private company is well-known for launching batches back-to-back, several times a month, regularly lofting up to 60 satellites at a time. And SpaceX plans to build up to perhaps as many as 30,000 eventually.
Most thought it was exciting to see the first few Starlink satellites traveling together in the night sky. But then more were launched, and then more. And astronomers began to worry.
Because Starlinks are bright, astronomers say they’re photobombing astronomical images. Therefore, they have the potential to interfere with the professional astronomical observations that have brought us our modern-day view of the cosmos. And although SpaceX has tried to address the issue, they remain far from what astronomers say is acceptable.
Bottom line: Get a list of all the SpaceX Starlink launches for July 2024 from both the West and East Coasts. Find out how to watch the livestream, and get updates, too.
On the morning of July 1, 2024, the waning crescent moon will lie close to the red planet Mars. Also nearby will be the bright planet Jupiter and the Pleiades star cluster. Keep watching for the Jupiter and Mars conjunction. They will be drawing closer together over the next 6 weeks. Their conjunction will be August 14. Chart via EarthSky.
As July opens
As July 2024 opens, Jupiter and Mars are near the waning crescent moon, and near each other, in the east before sunup. See the chart above. And – if you watch in the coming weeks – you’ll get to see Mars sideswipe Jupiter in a conjunction that’ll culminate on August 14. Start watching the two neighboring planets now (Mars is the 4th planet from the sun, and Jupiter the 5th). By mid-July, Mars will cross a constellation boundary into Taurus the Bull, where Jupiter is currently hanging out. There are many splendid things to see in Taurus. This conjunction will be fun!
The two are not far from the misty Pleiades star cluster.
A bonus planetary conjunction will happen on July 15, when Mars will be about half a degree from Uranus. Uranus is theoretically visible to the eye, but only in a dark sky and only then if your eyesight is perfect. So, around July, use binoculars to zero in on reddish Mars, then spot Uranus right beside it. Mars is red. And Uranus will be much fainter, and bluish-green in color.
Afterwards, Mars will pull away from Uranus. You’ll see it get a bit closer to the Pleiades, as it makes a beeline toward Jupiter. Just to make it even more interesting, the waning crescent moon enters the scene again on July 30.
On that date, bright Jupiter, red Mars, the bright star Aldebaran, the pretty Pleiades and the V-shaped Hyades star cluster will create quite a scene. They’ll all be in the eastern sky two hours before sunrise.
Then, the next morning, the moon – as an even thinner crescent – hangs a bit farther northeast of the celestial grouping.
We’re headed toward a Jupiter and Mars conjunction in August. Start watching the 2 planets now. For an especially dramatic scene, look during the early morning hours of July 30 and 31. The waning crescent moon joins Mars, Jupiter, the Pleiades, Aldebaran and the Hyades. Chart by John Jardine Goss/ EarthSky.
The big event: Jupiter and Mars conjunction August 14
The closest pairing of this planetary duo will come on the morning of August 14. That’s when bright gas giant Jupiter will get a visit from rocky red Mars on our sky’s dome. Then, the little planet will appear less than the width of a full moon from Jupiter. They’ll look close on our sky’s dome. In reality, the two will remain more than 300 million miles (500 million km) apart, even though they are next-door neighbors in our solar system.
Using just the unaided eye, the bright white light of Jupiter will contrast nicely with the dimmer and distinctly redder shine of Mars. In binoculars, Jupiter’s moons will enhance your enjoyment of the view. And this conjunction will be a great event for telescope owners and astrophotographers. You’ll be able to capture both planets in one view and thoroughly examine these remarkably different worlds. If you catch a great pic, please submit it to EarthSky’s community page!
Binoculars will help you see Mars pass bright Jupiter from August 10 through August 18. They’ll be at their closest to each other in the early morning hours of August 14. Chart by John Jardine Goss/ EarthSky.
For a precise view from your location, visit Stellarium.
Charts from Guy Ottewell
The following charts all come from U.K. astronomer Guy Ottewell. You’ll find charts like these for 2024 in his Astronomical Calendar.
On the morning of August 9, 2024, Jupiter and Mars will be nearing their closest approach to each other. Chart via Guy Ottewell’s 2024 Astronomical Calendar. Used with permission.On August 12, 2024, look for the Jupiter and Mars conjunction in the morning sky. The planets will be in the constellation Taurus. Chart via Guy Ottewell’s 2024 Astronomical Calendar. Used with permission.
Heliocentric solar system view of the planets in July and August 2024
Here’s a heliocentric view of the solar system from above for July and August when Mars and Jupiter will appear close together in the morning sky.
Bottom line: Start watching on July mornings for the upcoming Jupiter and Mars conjunction. The neighboring planets will get closer and closer – against the backdrop of the constellation Taurus the Bull – culminating on August 14, 2024.
On the morning of July 1, 2024, the waning crescent moon will lie close to the red planet Mars. Also nearby will be the bright planet Jupiter and the Pleiades star cluster. Keep watching for the Jupiter and Mars conjunction. They will be drawing closer together over the next 6 weeks. Their conjunction will be August 14. Chart via EarthSky.
As July opens
As July 2024 opens, Jupiter and Mars are near the waning crescent moon, and near each other, in the east before sunup. See the chart above. And – if you watch in the coming weeks – you’ll get to see Mars sideswipe Jupiter in a conjunction that’ll culminate on August 14. Start watching the two neighboring planets now (Mars is the 4th planet from the sun, and Jupiter the 5th). By mid-July, Mars will cross a constellation boundary into Taurus the Bull, where Jupiter is currently hanging out. There are many splendid things to see in Taurus. This conjunction will be fun!
The two are not far from the misty Pleiades star cluster.
A bonus planetary conjunction will happen on July 15, when Mars will be about half a degree from Uranus. Uranus is theoretically visible to the eye, but only in a dark sky and only then if your eyesight is perfect. So, around July, use binoculars to zero in on reddish Mars, then spot Uranus right beside it. Mars is red. And Uranus will be much fainter, and bluish-green in color.
Afterwards, Mars will pull away from Uranus. You’ll see it get a bit closer to the Pleiades, as it makes a beeline toward Jupiter. Just to make it even more interesting, the waning crescent moon enters the scene again on July 30.
On that date, bright Jupiter, red Mars, the bright star Aldebaran, the pretty Pleiades and the V-shaped Hyades star cluster will create quite a scene. They’ll all be in the eastern sky two hours before sunrise.
Then, the next morning, the moon – as an even thinner crescent – hangs a bit farther northeast of the celestial grouping.
We’re headed toward a Jupiter and Mars conjunction in August. Start watching the 2 planets now. For an especially dramatic scene, look during the early morning hours of July 30 and 31. The waning crescent moon joins Mars, Jupiter, the Pleiades, Aldebaran and the Hyades. Chart by John Jardine Goss/ EarthSky.
The big event: Jupiter and Mars conjunction August 14
The closest pairing of this planetary duo will come on the morning of August 14. That’s when bright gas giant Jupiter will get a visit from rocky red Mars on our sky’s dome. Then, the little planet will appear less than the width of a full moon from Jupiter. They’ll look close on our sky’s dome. In reality, the two will remain more than 300 million miles (500 million km) apart, even though they are next-door neighbors in our solar system.
Using just the unaided eye, the bright white light of Jupiter will contrast nicely with the dimmer and distinctly redder shine of Mars. In binoculars, Jupiter’s moons will enhance your enjoyment of the view. And this conjunction will be a great event for telescope owners and astrophotographers. You’ll be able to capture both planets in one view and thoroughly examine these remarkably different worlds. If you catch a great pic, please submit it to EarthSky’s community page!
Binoculars will help you see Mars pass bright Jupiter from August 10 through August 18. They’ll be at their closest to each other in the early morning hours of August 14. Chart by John Jardine Goss/ EarthSky.
For a precise view from your location, visit Stellarium.
Charts from Guy Ottewell
The following charts all come from U.K. astronomer Guy Ottewell. You’ll find charts like these for 2024 in his Astronomical Calendar.
On the morning of August 9, 2024, Jupiter and Mars will be nearing their closest approach to each other. Chart via Guy Ottewell’s 2024 Astronomical Calendar. Used with permission.On August 12, 2024, look for the Jupiter and Mars conjunction in the morning sky. The planets will be in the constellation Taurus. Chart via Guy Ottewell’s 2024 Astronomical Calendar. Used with permission.
Heliocentric solar system view of the planets in July and August 2024
Here’s a heliocentric view of the solar system from above for July and August when Mars and Jupiter will appear close together in the morning sky.
Bottom line: Start watching on July mornings for the upcoming Jupiter and Mars conjunction. The neighboring planets will get closer and closer – against the backdrop of the constellation Taurus the Bull – culminating on August 14, 2024.
