View larger. | Artist’s concept of an Earth-sized exoplanet, in this case LP 791-18 d, some 90 light-years away. Evidence suggests it’s a volcano-covered world, perhaps as active as Jupiter’s moon Io. So, what is a planet? Image via NASA/ Goddard Space Flight Center/ Chris Smith (KRBwyle).
On Monday, July 22, 2024, EarthSky’s Deborah Byrd will speak LIVE with Jean-Luc Margot, a Belgian-born astronomer and UCLA professor. Margot and his team just published a new study, outlining the reason we need a new definition of “planet.” They will present their ideas to the IAU General Assembly – a global meeting of astronomers – beginning on August 6 in Cape Town, South Africa.
When Pluto was demoted from full planet status in 2006, it was because the International Astronomical Union’s definition of a planet had changed. The change created an uproar. But, since the mid-1990s, scientists have discovered more than 5,000 exoplanets, or worlds orbiting distant stars. Meanwhile, the IAU definition applies only to planets within our solar system. The newly proposed planet definition is less sun-centric.
The new definition specifies that “planets” may orbit one or more stars, brown dwarfs or stellar remnants.
It sets mass limits that its originators say should apply to planets everywhere.
But does it return Pluto to full planet status?
Jean-Luc Margot and team published a new study in The Planetary Science Journal this past week (July 17, 2024) outlining their reasons for the suggested change in the definition to “planet.” Find their study here: Quantitative Criteria for Defining Planets.
Jean-Luc Margot is a Belgian-born astronomer and UCLA professor. He obtained a B.S. in electrical engineering from the University of Louvain (1993) and a Ph.D. in astronomy from Cornell University (1999). His research interests include the dynamics and geophysics of planetary bodies, radio and radar astronomy, and SETI. Image via The Planetary Society/ Jean-Luc Margot. Used with permission.
Bottom line: When the International Astronomical Union created a definition for “planet” in 2006, Pluto lost full planet status. Now astronomers are proposing a new definition of “planet.”
View larger. | Artist’s concept of an Earth-sized exoplanet, in this case LP 791-18 d, some 90 light-years away. Evidence suggests it’s a volcano-covered world, perhaps as active as Jupiter’s moon Io. So, what is a planet? Image via NASA/ Goddard Space Flight Center/ Chris Smith (KRBwyle).
On Monday, July 22, 2024, EarthSky’s Deborah Byrd will speak LIVE with Jean-Luc Margot, a Belgian-born astronomer and UCLA professor. Margot and his team just published a new study, outlining the reason we need a new definition of “planet.” They will present their ideas to the IAU General Assembly – a global meeting of astronomers – beginning on August 6 in Cape Town, South Africa.
When Pluto was demoted from full planet status in 2006, it was because the International Astronomical Union’s definition of a planet had changed. The change created an uproar. But, since the mid-1990s, scientists have discovered more than 5,000 exoplanets, or worlds orbiting distant stars. Meanwhile, the IAU definition applies only to planets within our solar system. The newly proposed planet definition is less sun-centric.
The new definition specifies that “planets” may orbit one or more stars, brown dwarfs or stellar remnants.
It sets mass limits that its originators say should apply to planets everywhere.
But does it return Pluto to full planet status?
Jean-Luc Margot and team published a new study in The Planetary Science Journal this past week (July 17, 2024) outlining their reasons for the suggested change in the definition to “planet.” Find their study here: Quantitative Criteria for Defining Planets.
Jean-Luc Margot is a Belgian-born astronomer and UCLA professor. He obtained a B.S. in electrical engineering from the University of Louvain (1993) and a Ph.D. in astronomy from Cornell University (1999). His research interests include the dynamics and geophysics of planetary bodies, radio and radar astronomy, and SETI. Image via The Planetary Society/ Jean-Luc Margot. Used with permission.
Bottom line: When the International Astronomical Union created a definition for “planet” in 2006, Pluto lost full planet status. Now astronomers are proposing a new definition of “planet.”
On July 16, 2024, the Royal Astronomical Society released the first image of a strange ‘garden sprinkler-like’ jet coming from a neutron star. The structure has an S shape, created as the jet changes direction due to the wobbling of the disk of hot gas around the star. The wobbling is due to a process called precession. Astronomers had observed precession with jets around black holes before but never with neutron stars.
This particular object sits in the binary system Circinus X-1, which is more than 30,000 light-years from Earth. It formed from the core of a massive supergiant star that collapsed around the same time Stonehenge was built. It is so dense that a teaspoon of its material weighs as much as Mount Everest.
Binary systems have two stars that are bound together by gravity. In the case of Circinus X-1, one of these is a neutron star.
Both neutron stars and black holes are cosmological monsters. They form when the biggest stars in the universe die and collapse under their own gravity.
However, black holes are considerably more massive. And scientists can only detect them through their gravitational effects. Meanwhile, scientists can observe neutron stars directly, despite their denseness. Neutron stars are some of the most extreme objects in the universe and have interiors almost entirely made of neutrons.
This is a radio image of the S-shaped neutron-star jet in Circinus X-1. Circinus X-1 is an X-ray binary star system with jets flowing outward. Scientists subtracted both the binary star system itself from the center of the image and a background source to make the S-shape clearer. The size of the jets against the sky is the same apparent size as a penny viewed from 328 feet (100 meters) away. But their real size is greater than 5 light-years. Image via Fraser Cowie/ Royal Astronomical Society.
Spotting the neutron-star jet
A team of astronomers at the University of Oxford used MeerKAT – a radio telescope in South Africa – to spot the jet emanating from the neutron star. The radio telescope created the most detailed high-resolution images of Circinus X-1.
The pictures – presented at this week’s National Astronomy Meeting at the University of Hull – include the first-ever image of an S-shaped jet coming from a confirmed neutron star. It’s a breakthrough that could help unravel the extreme physics behind the astronomical phenomenon.
Lead researcher Fraser Cowie of the University of Oxford said there was another system known for its S-shaped jets, called SS433, but recent results suggest that object is likely a black hole. Cowie said:
This image is the first time we have seen strong evidence for a precessing jet from a confirmed neutron star. This evidence comes from both the symmetric S shape of the radio-emitting plasma in the jets and from the fast, wide shockwave, which can only be produced by a jet changing direction. This will give valuable information about the extreme physics behind the launching of the jet, a phenomenon which is still not well understood.
This radio image from the MeerKAT telescope shows Circinus X-1 in the center within the spherical remnant of the supernova where it was born. The shockwaves from the jets are above and below Circinus X-1. A bright source in the background somewhat obscures the S-shape structure in the jets. Image via Fraser Cowie/ Royal Astronomical Society.
Accretion from a binary system
The neutron star’s huge density creates a strong force of gravity that strips gas from the companion star. That hot gas forms a disk that spirals down toward the neutron star’s surface.
This process, known as accretion, releases huge amounts of energy per second with more power than a million suns. Some of this energy powers jets – or narrow beams of outflowing material – from the binary system, traveling close to the speed of light.
Recent upgrades to the MeerKAT telescope have resulted in excellent sensitivity and higher-resolution images. With these the team saw clear evidence of an S-shaped structure, similar in shape to water spraying from a garden sprinkler, in Circinus X-1’s jet.
Not only that, but researchers also discovered moving termination shocks. These were the first recorded from an X-ray binary. These are regions where the jet violently rams into the surrounding material, causing a shockwave.
Cowie’s team measured the waves moving at roughly 10% the speed of light. This confirmed the fast-moving jet caused them and not something slower, such as a wind of material from the stars. Cowie said:
The fact that these shockwaves span a wide angle agrees with our model. So we have two strong pieces of evidence telling us the neutron star jet is precessing.
What are the jets made from?
Measuring the velocity of the shockwaves will also help astronomers understand what the jets causing them consist of.
The shockwaves effectively act as particle accelerators in space – producing high-energy cosmic rays – and the maximum energy of particles that can be accelerated depends on their velocity. Cowie said:
Circinus X-1 is one of the brightest objects in the X-ray sky and has been studied for over half a century. But despite this, it remains one of the most enigmatic systems we know of. Several aspects of its behavior are not well explained. So it’s very rewarding to help shed new light on this system, building on 50 years of work from others.
The next steps will be to continue to monitor the jets and see if they change over time in the way we expect. This will allow us to more precisely measure their properties and continue to learn more about this puzzling object.
Bottom line: Astronomers using the MeerKAT radio telescope in South Africa have observed a neutron-star jet with an S shape for the first time. The star’s wobble creates the jet’s S shape.
On July 16, 2024, the Royal Astronomical Society released the first image of a strange ‘garden sprinkler-like’ jet coming from a neutron star. The structure has an S shape, created as the jet changes direction due to the wobbling of the disk of hot gas around the star. The wobbling is due to a process called precession. Astronomers had observed precession with jets around black holes before but never with neutron stars.
This particular object sits in the binary system Circinus X-1, which is more than 30,000 light-years from Earth. It formed from the core of a massive supergiant star that collapsed around the same time Stonehenge was built. It is so dense that a teaspoon of its material weighs as much as Mount Everest.
Binary systems have two stars that are bound together by gravity. In the case of Circinus X-1, one of these is a neutron star.
Both neutron stars and black holes are cosmological monsters. They form when the biggest stars in the universe die and collapse under their own gravity.
However, black holes are considerably more massive. And scientists can only detect them through their gravitational effects. Meanwhile, scientists can observe neutron stars directly, despite their denseness. Neutron stars are some of the most extreme objects in the universe and have interiors almost entirely made of neutrons.
This is a radio image of the S-shaped neutron-star jet in Circinus X-1. Circinus X-1 is an X-ray binary star system with jets flowing outward. Scientists subtracted both the binary star system itself from the center of the image and a background source to make the S-shape clearer. The size of the jets against the sky is the same apparent size as a penny viewed from 328 feet (100 meters) away. But their real size is greater than 5 light-years. Image via Fraser Cowie/ Royal Astronomical Society.
Spotting the neutron-star jet
A team of astronomers at the University of Oxford used MeerKAT – a radio telescope in South Africa – to spot the jet emanating from the neutron star. The radio telescope created the most detailed high-resolution images of Circinus X-1.
The pictures – presented at this week’s National Astronomy Meeting at the University of Hull – include the first-ever image of an S-shaped jet coming from a confirmed neutron star. It’s a breakthrough that could help unravel the extreme physics behind the astronomical phenomenon.
Lead researcher Fraser Cowie of the University of Oxford said there was another system known for its S-shaped jets, called SS433, but recent results suggest that object is likely a black hole. Cowie said:
This image is the first time we have seen strong evidence for a precessing jet from a confirmed neutron star. This evidence comes from both the symmetric S shape of the radio-emitting plasma in the jets and from the fast, wide shockwave, which can only be produced by a jet changing direction. This will give valuable information about the extreme physics behind the launching of the jet, a phenomenon which is still not well understood.
This radio image from the MeerKAT telescope shows Circinus X-1 in the center within the spherical remnant of the supernova where it was born. The shockwaves from the jets are above and below Circinus X-1. A bright source in the background somewhat obscures the S-shape structure in the jets. Image via Fraser Cowie/ Royal Astronomical Society.
Accretion from a binary system
The neutron star’s huge density creates a strong force of gravity that strips gas from the companion star. That hot gas forms a disk that spirals down toward the neutron star’s surface.
This process, known as accretion, releases huge amounts of energy per second with more power than a million suns. Some of this energy powers jets – or narrow beams of outflowing material – from the binary system, traveling close to the speed of light.
Recent upgrades to the MeerKAT telescope have resulted in excellent sensitivity and higher-resolution images. With these the team saw clear evidence of an S-shaped structure, similar in shape to water spraying from a garden sprinkler, in Circinus X-1’s jet.
Not only that, but researchers also discovered moving termination shocks. These were the first recorded from an X-ray binary. These are regions where the jet violently rams into the surrounding material, causing a shockwave.
Cowie’s team measured the waves moving at roughly 10% the speed of light. This confirmed the fast-moving jet caused them and not something slower, such as a wind of material from the stars. Cowie said:
The fact that these shockwaves span a wide angle agrees with our model. So we have two strong pieces of evidence telling us the neutron star jet is precessing.
What are the jets made from?
Measuring the velocity of the shockwaves will also help astronomers understand what the jets causing them consist of.
The shockwaves effectively act as particle accelerators in space – producing high-energy cosmic rays – and the maximum energy of particles that can be accelerated depends on their velocity. Cowie said:
Circinus X-1 is one of the brightest objects in the X-ray sky and has been studied for over half a century. But despite this, it remains one of the most enigmatic systems we know of. Several aspects of its behavior are not well explained. So it’s very rewarding to help shed new light on this system, building on 50 years of work from others.
The next steps will be to continue to monitor the jets and see if they change over time in the way we expect. This will allow us to more precisely measure their properties and continue to learn more about this puzzling object.
Bottom line: Astronomers using the MeerKAT radio telescope in South Africa have observed a neutron-star jet with an S shape for the first time. The star’s wobble creates the jet’s S shape.
Mercury is our sun’s innermost planet. So it always lies near the sun in our sky. Mercury is now back in the west after sunset. It’ll reach its greatest elongation, its greatest apparent distance from the sun in our sky, on July 22, 2024. For more, see the two charts below:
The Mercury elongation of July 22, 2024, carries the innermost planet farther from the sun in our sky than any other Mercury elongation this year. Yet, from the Northern Hemisphere, Mercury is not outstandingly high in the sky after sunset. The reason is that the ecliptic – or path of the sun, moon and planets (shown as a gray line on this chart) – makes a relatively narrow angle with the evening horizon after sunset now. So Mercury’s distance from the sun is largely sideways along the western sunset horizon. You can see Mercury around its elongation. But you need to look soon after sunset to see it. Chart via Guy Ottewell’s blog. Used with permission.From Earth’s Southern Hemisphere around the time of the Mercury elongation on July 22, 2024, Mercury stands high in the west after sunset. The planet is easier to see – truly, more glorious – as seen from Earth’s Southern Hemisphere now because the ecliptic – the X line on this chart – stands nearly perpendicular to the sunset. Chart via Guy Ottewell’s blog. Used with permission.
Mercury after sunset in July 2024
Where to look: Look west, in the sunset direction – shortly after sunset – for Mercury. Greatest elongation: Mercury is farthest from the sun on our sky’s dome – and in fact farthest from the sun in the sky for all of 2024 – at 7 UTC (2 a.m. CDT) on July 22, 2024. At that time, Mercury will be 27 degrees from the sun in our sky. See A comparison of elongations, below. Brightness: Mercury was bright when it emerged in the evening sky during the last week of June. At that time, it was shining at -0.6 magnitude. At greatest elongation, Mercury shines more faintly at magnitude 0.3. But it’ll be barther from the sunset glare then and still brighter than most stars! In the evenings after greatest elongation, the innermost planet will rapidly fade as it sweeps up from behind Earth, in orbit around the sun, causing its illuminated side, or day side, to turn away from us. It’ll disappear in early August 2024 and will reach inferior conjunction – when it passes between Earth and the sun – on August 19. Through a telescope: Mercury will appear about 43% illuminated at greatest elongation. It’ll measure 7.8 arcseconds across. Constellation: Mercury will lie in front of the constellation Leo the Lion at this elongation. Doubtless, most of the stars in this constellation will be lost in the twilight. Note: As the innermost planet, Mercury is tied to the sun in our sky. As a result, it never ventures very far above the horizon after sunset. So as soon as the sun disappears below your horizon, your clock starts ticking. Will you see the glowing point of light that is Mercury before it drops below the horizon, following the setting sun? Note that this July, 2024, apparition of the sun’s innermost planet will be at its best for the year for the Southern Hemisphere.
Mercury in 1 minute
The video below gives you a 1-minute synopsis of the evening elongation of Mercury in July 2024.
Venus is up there, too
Venus – the brightest planet – also passed behind the sun recently and has officially re-entered the evening sky. It, too, is easier to spot from Earth’s Southern Hemisphere than from its Northern Hemisphere, and for the same reasons as mentioned above: because the angle of the ecliptic, or path of the sun, moon and planets is more favorable for Southern Hemisphere viewers. But Venus is much brighter than Mercury. Watch for it below Mercury in the western twilight. We’ve gotten only a few photographs of Venus so far from members of the EarthSky community. We present two below. The first is from Earth’s Northern Hemisphere, and the second is from Earth’s Southern Hemisphere.
View at EarthSky Community Photos. | Rita Raina of Rockville, Maryland, captured this image on July 7, 2024, and wrote: “I have never before seen Mercury. Yesterday evening the sky was clear and right below the 2 day old Moon was a bright Star. SkyView App said it was Mercury! And to top it, the star visible on the right lower corner, just above the horizon, was Venus, and that the star on the upper left corner was Regulus! A perfect straight line! i think I got lucky again, after a long time though!” Thank you, Rita!View at EarthSky Community Photos. | Peter Lowenstein in Mutare, Zimbabwe, created this montage this week. It’s the brightest planet, Venus, now back in the evening sky. You’ll find it exceedingly low in the sky after sunset, near the sunset glare. This montage shows it setting behind the sun. Peter wrote: “On July 15, I obtained good views of a full Venus, setting behind a tree in fading volcanic sunset glow, shortly after sundown. A full Venus is rare to see, because the planet only appears full from Earth when on the far side of the sun.” Venus has just emerged from being behind the sun. It’ll get higher in the western twilight sky as the weeks pass. How soon will you see it? For more, visit EarthSky’s night sky guide.
For precise sun and Mercury rising times at your location:
Jan 12, 2024: Greatest elongation (morning) Feb 28, 2024: Superior conjunction (passes behind sun from Earth) Mar 24, 2024: Greatest elongation (evening) Apr 11, 2024: Inferior conjunction (races between Earth and sun) May 9, 2024: Greatest elongation (morning) Jun 14, 2024: Superior conjunction (passes behind sun from Earth) Jul 22, 2024: Greatest elongation (evening) Aug 19, 2024: Inferior conjunction (races between Earth and sun) Sep 5, 2024: Greatest elongation (morning) Sep 30, 2024: Superior conjunction (passes behind sun from Earth) Nov 16, 2024: Greatest elongation (evening) Dec 5, 2024: Inferior conjunction (races between Earth and sun) Dec 25, 2024: Greatest elongation (morning)
In July 2024, Mercury stretches out a full 27 degrees from the sun in our sky. The farthest from the sun that Mercury can ever appear on the sky’s dome is about 28 degrees. And the least distance is around 18 degrees.
Mercury (and Venus) elongations are better or worse depending on the time of the year they occur. So in 2024, the Southern Hemisphere will have the best evening elongation of Mercury in July 2024. And the Northern Hemisphere will have the best evening apparition in March.
In the autumn for either hemisphere, the ecliptic – or path of the sun, moon and planets – makes a narrow angle to the horizon in the evening. But it makes a steep slant, nearly perpendicular, in the morning. So, in autumn from either hemisphere, morning elongations of Mercury are best. That’s when Mercury appears higher above the horizon and farther from the glow of the sun. However, evening elongations in autumn are harder to see.
In the spring for either hemisphere, the situation reverses. The ecliptic and horizon meet at a sharper angle on spring evenings and a narrower angle on spring mornings. So, in springtime for either hemisphere, evening elongations of Mercury are best. Meanwhile, morning elongations in springtime are harder to see.
Mercury elongations compared. Here, gray areas represent evening apparitions (eastward elongation). Blue areas represent morning apparitions (westward elongation). The top figures are the maximum elongations, reached at the top dates shown beneath. Curves show the altitude of the planet above the horizon at sunrise or sunset, for latitude 40 degrees north (thick line) and 35 degrees south (thin line). Maxima are reached at the parenthesized dates below (40 degrees north bold). Chart via Guy Ottewell’s 2024 Astronomical Calendar. Used with permission.
More Mercury evening elongation comparisons for 2024
Mercury’s greatest evening elongations in 2024 from the Northern Hemisphere as viewed through a powerful telescope. The planet images are at the 1st, 11th, and 21st of each month. Dots show the actual positions of the planet for every day. Chart via Guy Ottewell’s 2024 Astronomical Calendar. Used with permission.Mercury’s greatest evening elongations in 2024 from the Southern Hemisphere as viewed through a powerful telescope. The planet images are at the 1st, 11th, and 21st of each month. Dots show the actual positions of the planet for every day. Chart via Guy Ottewell’s 2024 Astronomical Calendar. Used with permission.
Mercury elongations
At greatest elongation, Mercury is to one side of the sun and is at its greatest distance from the sun on our sky’s dome. Mercury reaches greatest eastern (evening) elongation from the sun on July 22, 2024. It is then 27 degrees from the sun in the evening sky. This July elongation carries Mercury as far from the sun as it will be in 2024. Chart via EarthSky. .
Bottom line: The sun’s innermost planet, Mercury, will stretch out a full 27 degrees from the sunset on July 22, 2024. That is nearly as far from the sunset as Mercury can be.
Mercury is our sun’s innermost planet. So it always lies near the sun in our sky. Mercury is now back in the west after sunset. It’ll reach its greatest elongation, its greatest apparent distance from the sun in our sky, on July 22, 2024. For more, see the two charts below:
The Mercury elongation of July 22, 2024, carries the innermost planet farther from the sun in our sky than any other Mercury elongation this year. Yet, from the Northern Hemisphere, Mercury is not outstandingly high in the sky after sunset. The reason is that the ecliptic – or path of the sun, moon and planets (shown as a gray line on this chart) – makes a relatively narrow angle with the evening horizon after sunset now. So Mercury’s distance from the sun is largely sideways along the western sunset horizon. You can see Mercury around its elongation. But you need to look soon after sunset to see it. Chart via Guy Ottewell’s blog. Used with permission.From Earth’s Southern Hemisphere around the time of the Mercury elongation on July 22, 2024, Mercury stands high in the west after sunset. The planet is easier to see – truly, more glorious – as seen from Earth’s Southern Hemisphere now because the ecliptic – the X line on this chart – stands nearly perpendicular to the sunset. Chart via Guy Ottewell’s blog. Used with permission.
Mercury after sunset in July 2024
Where to look: Look west, in the sunset direction – shortly after sunset – for Mercury. Greatest elongation: Mercury is farthest from the sun on our sky’s dome – and in fact farthest from the sun in the sky for all of 2024 – at 7 UTC (2 a.m. CDT) on July 22, 2024. At that time, Mercury will be 27 degrees from the sun in our sky. See A comparison of elongations, below. Brightness: Mercury was bright when it emerged in the evening sky during the last week of June. At that time, it was shining at -0.6 magnitude. At greatest elongation, Mercury shines more faintly at magnitude 0.3. But it’ll be barther from the sunset glare then and still brighter than most stars! In the evenings after greatest elongation, the innermost planet will rapidly fade as it sweeps up from behind Earth, in orbit around the sun, causing its illuminated side, or day side, to turn away from us. It’ll disappear in early August 2024 and will reach inferior conjunction – when it passes between Earth and the sun – on August 19. Through a telescope: Mercury will appear about 43% illuminated at greatest elongation. It’ll measure 7.8 arcseconds across. Constellation: Mercury will lie in front of the constellation Leo the Lion at this elongation. Doubtless, most of the stars in this constellation will be lost in the twilight. Note: As the innermost planet, Mercury is tied to the sun in our sky. As a result, it never ventures very far above the horizon after sunset. So as soon as the sun disappears below your horizon, your clock starts ticking. Will you see the glowing point of light that is Mercury before it drops below the horizon, following the setting sun? Note that this July, 2024, apparition of the sun’s innermost planet will be at its best for the year for the Southern Hemisphere.
Mercury in 1 minute
The video below gives you a 1-minute synopsis of the evening elongation of Mercury in July 2024.
Venus is up there, too
Venus – the brightest planet – also passed behind the sun recently and has officially re-entered the evening sky. It, too, is easier to spot from Earth’s Southern Hemisphere than from its Northern Hemisphere, and for the same reasons as mentioned above: because the angle of the ecliptic, or path of the sun, moon and planets is more favorable for Southern Hemisphere viewers. But Venus is much brighter than Mercury. Watch for it below Mercury in the western twilight. We’ve gotten only a few photographs of Venus so far from members of the EarthSky community. We present two below. The first is from Earth’s Northern Hemisphere, and the second is from Earth’s Southern Hemisphere.
View at EarthSky Community Photos. | Rita Raina of Rockville, Maryland, captured this image on July 7, 2024, and wrote: “I have never before seen Mercury. Yesterday evening the sky was clear and right below the 2 day old Moon was a bright Star. SkyView App said it was Mercury! And to top it, the star visible on the right lower corner, just above the horizon, was Venus, and that the star on the upper left corner was Regulus! A perfect straight line! i think I got lucky again, after a long time though!” Thank you, Rita!View at EarthSky Community Photos. | Peter Lowenstein in Mutare, Zimbabwe, created this montage this week. It’s the brightest planet, Venus, now back in the evening sky. You’ll find it exceedingly low in the sky after sunset, near the sunset glare. This montage shows it setting behind the sun. Peter wrote: “On July 15, I obtained good views of a full Venus, setting behind a tree in fading volcanic sunset glow, shortly after sundown. A full Venus is rare to see, because the planet only appears full from Earth when on the far side of the sun.” Venus has just emerged from being behind the sun. It’ll get higher in the western twilight sky as the weeks pass. How soon will you see it? For more, visit EarthSky’s night sky guide.
For precise sun and Mercury rising times at your location:
Jan 12, 2024: Greatest elongation (morning) Feb 28, 2024: Superior conjunction (passes behind sun from Earth) Mar 24, 2024: Greatest elongation (evening) Apr 11, 2024: Inferior conjunction (races between Earth and sun) May 9, 2024: Greatest elongation (morning) Jun 14, 2024: Superior conjunction (passes behind sun from Earth) Jul 22, 2024: Greatest elongation (evening) Aug 19, 2024: Inferior conjunction (races between Earth and sun) Sep 5, 2024: Greatest elongation (morning) Sep 30, 2024: Superior conjunction (passes behind sun from Earth) Nov 16, 2024: Greatest elongation (evening) Dec 5, 2024: Inferior conjunction (races between Earth and sun) Dec 25, 2024: Greatest elongation (morning)
In July 2024, Mercury stretches out a full 27 degrees from the sun in our sky. The farthest from the sun that Mercury can ever appear on the sky’s dome is about 28 degrees. And the least distance is around 18 degrees.
Mercury (and Venus) elongations are better or worse depending on the time of the year they occur. So in 2024, the Southern Hemisphere will have the best evening elongation of Mercury in July 2024. And the Northern Hemisphere will have the best evening apparition in March.
In the autumn for either hemisphere, the ecliptic – or path of the sun, moon and planets – makes a narrow angle to the horizon in the evening. But it makes a steep slant, nearly perpendicular, in the morning. So, in autumn from either hemisphere, morning elongations of Mercury are best. That’s when Mercury appears higher above the horizon and farther from the glow of the sun. However, evening elongations in autumn are harder to see.
In the spring for either hemisphere, the situation reverses. The ecliptic and horizon meet at a sharper angle on spring evenings and a narrower angle on spring mornings. So, in springtime for either hemisphere, evening elongations of Mercury are best. Meanwhile, morning elongations in springtime are harder to see.
Mercury elongations compared. Here, gray areas represent evening apparitions (eastward elongation). Blue areas represent morning apparitions (westward elongation). The top figures are the maximum elongations, reached at the top dates shown beneath. Curves show the altitude of the planet above the horizon at sunrise or sunset, for latitude 40 degrees north (thick line) and 35 degrees south (thin line). Maxima are reached at the parenthesized dates below (40 degrees north bold). Chart via Guy Ottewell’s 2024 Astronomical Calendar. Used with permission.
More Mercury evening elongation comparisons for 2024
Mercury’s greatest evening elongations in 2024 from the Northern Hemisphere as viewed through a powerful telescope. The planet images are at the 1st, 11th, and 21st of each month. Dots show the actual positions of the planet for every day. Chart via Guy Ottewell’s 2024 Astronomical Calendar. Used with permission.Mercury’s greatest evening elongations in 2024 from the Southern Hemisphere as viewed through a powerful telescope. The planet images are at the 1st, 11th, and 21st of each month. Dots show the actual positions of the planet for every day. Chart via Guy Ottewell’s 2024 Astronomical Calendar. Used with permission.
Mercury elongations
At greatest elongation, Mercury is to one side of the sun and is at its greatest distance from the sun on our sky’s dome. Mercury reaches greatest eastern (evening) elongation from the sun on July 22, 2024. It is then 27 degrees from the sun in the evening sky. This July elongation carries Mercury as far from the sun as it will be in 2024. Chart via EarthSky. .
Bottom line: The sun’s innermost planet, Mercury, will stretch out a full 27 degrees from the sunset on July 22, 2024. That is nearly as far from the sunset as Mercury can be.
When to watch in 2024: Overnight of July 20. Where to look: Look for the bright round moon in the east in the evening of July 20, highest in the sky around midnight, and in the west before sunrise morning on July 21. Crest of the full moon falls at 10:17 UTC (5:17 a.m. CDT) on July 21. So, if you live in either North or South America, your fullest moon hangs somewhere above the western horizon just before sunrise on July 21.
All full moons rise along the eastern horizon near sunset, and set along the western horizon near sunrise. They are visible all night. At full moon, the sun, Earth and moon are aligned in space, with Earth in the middle. The moon’s day side – its fully lighted hemisphere – directly faces us. That’s why the moon appears full. Note that the moon will look full and round the day before and the day after it reaches its fullest.
The July full moon will occur at 10:17 UTC on July 21. That is 5:17 a.m. on July 21 in the central United States. On the evening of July 20, the moon will rise in the east just before sunset and will lie east of the Teapot asterism of Sagittarius. Chart via EarthSky.At full moon, the sun, Earth, and moon are aligned, with Earth in the middle. The moon’s day side – its fully lighted hemisphere – directly faces us. Chart via EarthSky.
It’s the Buck Moon
All the full moons have names. Popular nicknames for the July full moon include the Feather Molting Moon and the Salmon Moon, but Buck Moon is the most common. At this time of year the antlers of male deer grow rapidly, sometimes to an impressive size. Hence, the name Buck Moon. Some Native Americans used the names Thunder Moon, Berry Moon and Raspberry Moon.
The 2024 July full moon falls in the morning of July 21 (at 5:17 a.m. CDT) and lies in eastern Sagittarius. It will appear full on the overnights of July 20 and 21. Chart via EarthSky.
July full moon is in Sagittarius in 2024
The July full moon can lie in front of two constellations of the zodiac. Most frequently it appears in Sagittarius the Archer, and less often in the constellation to Sagittarius’ east, Capricornus the Sea Goat. This full moon glows in far eastern Sagittarius near its border with Capricornus. Because of the bright moonlight, the stars in the vicinity of the moon will be very difficult to see with the unaided eye.
This July full moon mimics January sun
Because a full moon more or less stays opposite the sun, the full moon’s nighttime path mimics the sun’s daytime path from six months ago, or six months hence. In this case, it’s following the path the sun took at the end of the third week in January. Since the January sun arcs relatively low across the sky, so does the July full moon.
North of the Arctic Circle, the January sun either never climbs above the horizon or only a short bit above it. This July full moon does the same.
Meanwhile, in the Southern Hemisphere, the moon’s path across the sky will nearly mirror that of the high summer solstice sun.
And, south of the Antarctic Circle, the moon will be out for 24 hours around the clock or nearly so, matching the path of the January sun.
Arc of the July full moon, Northern Hemisphere
The moon’s arc across our sky varies from month to month and from season to season. Every full moon rises somewhere along the eastern horizon, opposite the sun as it sets in the west. And every full moon arcs across the sky throughout the night and sets along the western horizon around dawn. For us in the Northern Hemisphere, in most years the arc of July’s full moon is lower than any other, except June’s.
For observers in the Northern Hemisphere, the low arc across the sky of the July full moon nearly matches the path of the January sun. The arc of the July sun is always much higher than the arc of the July full moon. Chart via EarthSky.
Arc of the July full moon, Southern Hemisphere
For those in the Southern Hemisphere, the July full moon’s arc across the sky reaches not quite as high as June’s, since it matches the path of January’s sun.
For observers in the Southern Hemisphere, the high arc across the sky of the July full moon nearly matches the path of the January sun. The arc of the July sun is always much lower than the arc of the July full moon. Chart via EarthSky.
Bottom line: The July full moon – the Buck Moon – falls overnight on July 20, reaching its fullest at 10:17 UTC (5:17 a.m. CDT) the morning of July 21.
When to watch in 2024: Overnight of July 20. Where to look: Look for the bright round moon in the east in the evening of July 20, highest in the sky around midnight, and in the west before sunrise morning on July 21. Crest of the full moon falls at 10:17 UTC (5:17 a.m. CDT) on July 21. So, if you live in either North or South America, your fullest moon hangs somewhere above the western horizon just before sunrise on July 21.
All full moons rise along the eastern horizon near sunset, and set along the western horizon near sunrise. They are visible all night. At full moon, the sun, Earth and moon are aligned in space, with Earth in the middle. The moon’s day side – its fully lighted hemisphere – directly faces us. That’s why the moon appears full. Note that the moon will look full and round the day before and the day after it reaches its fullest.
The July full moon will occur at 10:17 UTC on July 21. That is 5:17 a.m. on July 21 in the central United States. On the evening of July 20, the moon will rise in the east just before sunset and will lie east of the Teapot asterism of Sagittarius. Chart via EarthSky.At full moon, the sun, Earth, and moon are aligned, with Earth in the middle. The moon’s day side – its fully lighted hemisphere – directly faces us. Chart via EarthSky.
It’s the Buck Moon
All the full moons have names. Popular nicknames for the July full moon include the Feather Molting Moon and the Salmon Moon, but Buck Moon is the most common. At this time of year the antlers of male deer grow rapidly, sometimes to an impressive size. Hence, the name Buck Moon. Some Native Americans used the names Thunder Moon, Berry Moon and Raspberry Moon.
The 2024 July full moon falls in the morning of July 21 (at 5:17 a.m. CDT) and lies in eastern Sagittarius. It will appear full on the overnights of July 20 and 21. Chart via EarthSky.
July full moon is in Sagittarius in 2024
The July full moon can lie in front of two constellations of the zodiac. Most frequently it appears in Sagittarius the Archer, and less often in the constellation to Sagittarius’ east, Capricornus the Sea Goat. This full moon glows in far eastern Sagittarius near its border with Capricornus. Because of the bright moonlight, the stars in the vicinity of the moon will be very difficult to see with the unaided eye.
This July full moon mimics January sun
Because a full moon more or less stays opposite the sun, the full moon’s nighttime path mimics the sun’s daytime path from six months ago, or six months hence. In this case, it’s following the path the sun took at the end of the third week in January. Since the January sun arcs relatively low across the sky, so does the July full moon.
North of the Arctic Circle, the January sun either never climbs above the horizon or only a short bit above it. This July full moon does the same.
Meanwhile, in the Southern Hemisphere, the moon’s path across the sky will nearly mirror that of the high summer solstice sun.
And, south of the Antarctic Circle, the moon will be out for 24 hours around the clock or nearly so, matching the path of the January sun.
Arc of the July full moon, Northern Hemisphere
The moon’s arc across our sky varies from month to month and from season to season. Every full moon rises somewhere along the eastern horizon, opposite the sun as it sets in the west. And every full moon arcs across the sky throughout the night and sets along the western horizon around dawn. For us in the Northern Hemisphere, in most years the arc of July’s full moon is lower than any other, except June’s.
For observers in the Northern Hemisphere, the low arc across the sky of the July full moon nearly matches the path of the January sun. The arc of the July sun is always much higher than the arc of the July full moon. Chart via EarthSky.
Arc of the July full moon, Southern Hemisphere
For those in the Southern Hemisphere, the July full moon’s arc across the sky reaches not quite as high as June’s, since it matches the path of January’s sun.
For observers in the Southern Hemisphere, the high arc across the sky of the July full moon nearly matches the path of the January sun. The arc of the July sun is always much lower than the arc of the July full moon. Chart via EarthSky.
Bottom line: The July full moon – the Buck Moon – falls overnight on July 20, reaching its fullest at 10:17 UTC (5:17 a.m. CDT) the morning of July 21.
The world watched on television as Neil Armstrong from Apollo 11 was the first human to leave footsteps on the moon on July 20, 1969. It was the first time humans walked on another world as he stepped onto the lunar surface, Armstrong said: “That is one small step for [a] man, one giant leap for mankind.” Still image via NASA video.
The Eagle has landed and footsteps on the moon
On July 20, 1969, Apollo 11 astronauts Buzz Aldrin and Neil Armstrong landed their moon module on a broad dark lunar lava flow, called the Sea of Tranquility. And six hours later, Neil Armstrong became the first human being to walk on the surface of a world beyond Earth.
In the video below, you can hear the excitement in Armstrong’s voice at the successful landing of Eagle on the moon’s surface as he says:
Tranquility Base here. The Eagle has landed.
The first footsteps on the moon, leaving human footprints on the moon. Image via NASA.
Altogether, Armstrong and Aldrin spent 21 1/2 hours on the moon’s surface. Furthermore, they collected 47.5 pounds (21.5 kg) of moon rocks for return to Earth. And then they blasted off in their module from the lunar surface to meet up with Michael Collins in the command module orbiting overhead.
Finally they returned safely to Earth and landed in the Pacific Ocean on July 24, 1969.
The Apollo 11 launch
Apollo 11 launched at 13:32:00 UTC (9:32:00 a.m. EDT local time) on July 16, 1969. Astronauts Neil A. Armstrong, Michael Collins and Edwin E. “Buzz” Aldrin, Jr., were aboard. Image via Wikipedia.Apollo 11 left Earth via a type of rocket not longer in use, called Saturn V. The giant Saturn V rocket was 111 meters (363 feet) tall, about the height of a 36-story-tall building. Read more about the Saturn V rocket. Image via Wikimedia.Apollo 11 orbited Earth 1 1/2 times. Twelve minutes after launch, it separated from the Saturn V rocket, as a propulsion maneuver sent it on a path toward the moon. Meanwhile here is a view of Earth from Apollo 11, shortly after it left Earth orbit. Image via Wikimedia.
Apollo 11: Watching from mission control
Happy Apollo 11 mission officials in the Launch Control Center following the successful Apollo 11 liftoff on July 16, 1969. That is the famous German rocket engineer Wernher von Braun, 4th from left (with binoculars). Read more about Wernher von Braun. Image via NASA.
Oh what a view for the Apollo 11 astronauts
Buzz Aldrin looks into a TV camera during the 3rd broadcast from space on the way to the moon. Image via NASA.Earth seen by Apollo 11 astronauts on their way to the moon. Image via NASA.The Eagle lunar module captured this image of the Columbia command module in lunar orbit. Meanwhile Columbia stayed in lunar orbit with Michael Collins aboard during Eagle’s descent and landing. Image via NASA.
The lunar module and Saturn V
Here is the Apollo 11 lunar module, the vehicle that would carry Neil Armstrong and Buzz Aldrin to the moon’s surface. It was called “Eagle.” This photo also shows the module in its landing configuration, photographed in lunar orbit from the command module, which was called “Columbia.” Astronaut Michael Collins, alone aboard Columbia, inspected Eagle as it pirouetted before him to ensure the craft was not damaged. Image via Wikimedia.The Apollo command module’s position atop the Saturn V at launch. The lunar module – the craft that descended to the moon’s surface – is positioned just below the command module in this diagram. Image via Wikimedia.
There are now 2 heavy lift rockets, either of which could be used for moon missions. Read about SLS v Starship.
Concerns about the surface for footsteps on the moon
An early concern of space engineers had been that the lunar regolith, the fine soil covering the moon, would be soft like quicksand. There was some fear that the Eagle lunar module would sink after landing. Hence Armstrong’s comment about the depth of the footpads in the lunar soil as he descended the ladder before stepping onto the moon.
Buzz Aldrin descends the steps of the lunar module ladder as he becomes the second human being to walk on the moon. Image via NASA.Armstrong and Aldrin beginning work on the moon. This included deploying a U.S. flag, performing several science experiments, and collecting moon rocks. Still image via NASA video.Here is Buzz Aldrin, who piloted the lunar module Eagle to the moon’s surface, with the LR-3, a reflecting array designed to bounce laser beams fired from Earth back to Earth. This experiment helped refine our knowledge of the moon’s distance and the shape of its orbit around Earth. Image via NASA.Lastly, the lunar module Eagle on the surface of the moon. Image via Wikimedia.
Holding down the fort with a great view
Neil Armstrong in the lunar module Eagle shortly after his historic 1st moonwalk, when he became the 1st human to set foot on a world besides Earth. Image via Wikipedia.Michael Collins caught this photo of the lunar module with Armstrong and Aldrin inside – and with Earth in the distance – as the module ascended from the moon’s surface to rejoin the command module. The lunar module docked with the orbiting command module, and, shortly afterwards, the astronauts began their journey back to Earth. Image via Wikimedia.
Splashdown and celebrations for a successful return
There were no runway landings in those days. Splashdown for the 3 astronauts was in the Pacific Ocean. Here, they await pickup by a helicopter from the USS Hornet. Image via Wikipedia.Celebration at Mission Control as Apollo 11 draws to a successful end. Image via NASA.Ticker-tape parade for the Apollo 11 astronauts in New York City on August 13, 1969. This section of Broadway is known as the Canyon of Heroes. Image via Wikimedia.
A bounty of moon rocks brought back to Earth
The Apollo astronauts brought the 1st moon rocks back to Earth. Here is a sample.
August 5, 1969 – NASA displays moon rocks brought back with the Apollo 11 mission. The rock box was opened for the first time in the Vacuum Laboratory of Johnson Space Center’s Lunar Receiving Laboratory. pic.twitter.com/Eka8sss6Z6
This lunar sample, known as 10057, was collected during Apollo 11 and later sliced into pieces. Image via NASA.
Experience the Apollo 11 landing site as it appears today, in this video:
Bottom line: This week is the 55th anniversary of humanity’s historic Apollo moon landing and the first human footsteps on the moon. The story in pictures, here.
The world watched on television as Neil Armstrong from Apollo 11 was the first human to leave footsteps on the moon on July 20, 1969. It was the first time humans walked on another world as he stepped onto the lunar surface, Armstrong said: “That is one small step for [a] man, one giant leap for mankind.” Still image via NASA video.
The Eagle has landed and footsteps on the moon
On July 20, 1969, Apollo 11 astronauts Buzz Aldrin and Neil Armstrong landed their moon module on a broad dark lunar lava flow, called the Sea of Tranquility. And six hours later, Neil Armstrong became the first human being to walk on the surface of a world beyond Earth.
In the video below, you can hear the excitement in Armstrong’s voice at the successful landing of Eagle on the moon’s surface as he says:
Tranquility Base here. The Eagle has landed.
The first footsteps on the moon, leaving human footprints on the moon. Image via NASA.
Altogether, Armstrong and Aldrin spent 21 1/2 hours on the moon’s surface. Furthermore, they collected 47.5 pounds (21.5 kg) of moon rocks for return to Earth. And then they blasted off in their module from the lunar surface to meet up with Michael Collins in the command module orbiting overhead.
Finally they returned safely to Earth and landed in the Pacific Ocean on July 24, 1969.
The Apollo 11 launch
Apollo 11 launched at 13:32:00 UTC (9:32:00 a.m. EDT local time) on July 16, 1969. Astronauts Neil A. Armstrong, Michael Collins and Edwin E. “Buzz” Aldrin, Jr., were aboard. Image via Wikipedia.Apollo 11 left Earth via a type of rocket not longer in use, called Saturn V. The giant Saturn V rocket was 111 meters (363 feet) tall, about the height of a 36-story-tall building. Read more about the Saturn V rocket. Image via Wikimedia.Apollo 11 orbited Earth 1 1/2 times. Twelve minutes after launch, it separated from the Saturn V rocket, as a propulsion maneuver sent it on a path toward the moon. Meanwhile here is a view of Earth from Apollo 11, shortly after it left Earth orbit. Image via Wikimedia.
Apollo 11: Watching from mission control
Happy Apollo 11 mission officials in the Launch Control Center following the successful Apollo 11 liftoff on July 16, 1969. That is the famous German rocket engineer Wernher von Braun, 4th from left (with binoculars). Read more about Wernher von Braun. Image via NASA.
Oh what a view for the Apollo 11 astronauts
Buzz Aldrin looks into a TV camera during the 3rd broadcast from space on the way to the moon. Image via NASA.Earth seen by Apollo 11 astronauts on their way to the moon. Image via NASA.The Eagle lunar module captured this image of the Columbia command module in lunar orbit. Meanwhile Columbia stayed in lunar orbit with Michael Collins aboard during Eagle’s descent and landing. Image via NASA.
The lunar module and Saturn V
Here is the Apollo 11 lunar module, the vehicle that would carry Neil Armstrong and Buzz Aldrin to the moon’s surface. It was called “Eagle.” This photo also shows the module in its landing configuration, photographed in lunar orbit from the command module, which was called “Columbia.” Astronaut Michael Collins, alone aboard Columbia, inspected Eagle as it pirouetted before him to ensure the craft was not damaged. Image via Wikimedia.The Apollo command module’s position atop the Saturn V at launch. The lunar module – the craft that descended to the moon’s surface – is positioned just below the command module in this diagram. Image via Wikimedia.
There are now 2 heavy lift rockets, either of which could be used for moon missions. Read about SLS v Starship.
Concerns about the surface for footsteps on the moon
An early concern of space engineers had been that the lunar regolith, the fine soil covering the moon, would be soft like quicksand. There was some fear that the Eagle lunar module would sink after landing. Hence Armstrong’s comment about the depth of the footpads in the lunar soil as he descended the ladder before stepping onto the moon.
Buzz Aldrin descends the steps of the lunar module ladder as he becomes the second human being to walk on the moon. Image via NASA.Armstrong and Aldrin beginning work on the moon. This included deploying a U.S. flag, performing several science experiments, and collecting moon rocks. Still image via NASA video.Here is Buzz Aldrin, who piloted the lunar module Eagle to the moon’s surface, with the LR-3, a reflecting array designed to bounce laser beams fired from Earth back to Earth. This experiment helped refine our knowledge of the moon’s distance and the shape of its orbit around Earth. Image via NASA.Lastly, the lunar module Eagle on the surface of the moon. Image via Wikimedia.
Holding down the fort with a great view
Neil Armstrong in the lunar module Eagle shortly after his historic 1st moonwalk, when he became the 1st human to set foot on a world besides Earth. Image via Wikipedia.Michael Collins caught this photo of the lunar module with Armstrong and Aldrin inside – and with Earth in the distance – as the module ascended from the moon’s surface to rejoin the command module. The lunar module docked with the orbiting command module, and, shortly afterwards, the astronauts began their journey back to Earth. Image via Wikimedia.
Splashdown and celebrations for a successful return
There were no runway landings in those days. Splashdown for the 3 astronauts was in the Pacific Ocean. Here, they await pickup by a helicopter from the USS Hornet. Image via Wikipedia.Celebration at Mission Control as Apollo 11 draws to a successful end. Image via NASA.Ticker-tape parade for the Apollo 11 astronauts in New York City on August 13, 1969. This section of Broadway is known as the Canyon of Heroes. Image via Wikimedia.
A bounty of moon rocks brought back to Earth
The Apollo astronauts brought the 1st moon rocks back to Earth. Here is a sample.
August 5, 1969 – NASA displays moon rocks brought back with the Apollo 11 mission. The rock box was opened for the first time in the Vacuum Laboratory of Johnson Space Center’s Lunar Receiving Laboratory. pic.twitter.com/Eka8sss6Z6
This lunar sample, known as 10057, was collected during Apollo 11 and later sliced into pieces. Image via NASA.
Experience the Apollo 11 landing site as it appears today, in this video:
Bottom line: This week is the 55th anniversary of humanity’s historic Apollo moon landing and the first human footsteps on the moon. The story in pictures, here.
Frogs around the world are being wiped out by a deadly fungus.
The chytrid fungus has caused some 90 frog species to go extinct.
Scientists found “frog saunas” can help warm frogs and fight off the fungus. The frogs didn’t need any encouragement, flocking to the saunas in winter.
You can make a frog sauna with simple materials to help save frogs. Researchers used a masonry brick with holes, veggie greenhouse, black paint and cable ties.
This catastrophic and ongoing biodiversity loss surpasses the devastation wrought by other notorious invasive species such as cats, rats and even cane toads. Short of removing species from the wild and treating them in captivity, few strategies exist to deal with the chytrid threat.
Our new research, published June 26, 2024, in the journal Nature, offers a promising option.
Outbreaks of chytrid (pronounced “KY-trid”) are more common in cold winter months, just like seasonal human flu. We found a way to combat these winter outbreaks using heat. Our purpose-built “frog saunas” allow affected amphibians to warm up and bake off their infections. They are so simple you can build a frog sauna using supplies from the hardware store.
If frogs’ good looks are not enough for you to care about their welfare, perhaps learning how they contribute to the environment or human health will pique your interest.
Frogs eat insects that carry and spread human diseases. Their skin is also a rich source of new medicines that could help us combat antibiotic-resistant superbugs or curb the startling increase in opioid addiction.
Often starting life as a tadpole eating algae, before morphing into a carnivorous adult, frogs carry energy from aquatic ecosystems onto land. There it can be transferred throughout the food web. So losing a single frog species can have serious flow-on effects.
The green and golden bell frog has declined from more than 90% of its former range since the chytrid fungus arrived in Australia. Image via Anthony Waddle/ The Conversation.
The origin and spread of chytrid
It’s likely the chytrid fungus originated in Asia. The pathogen there seems to coexist with native amphibians. But chytrid is deadly elsewhere, possibly because other frogs have no natural defenses.
Chytrid harms frogs by disrupting the integrity of their skin. It depletes electrolytes needed for heart function. Infected frogs can die of cardiac arrest.
Chytrid has spread worldwide through the trade of amphibians, becoming a seemingly permanent part of ecosystems. As eradicating chytrid from the wild is not possible, we need a way to help frogs battle infection.
Chytrid: the frog-killing fungus, featuring Associate Professor Lee Berger (Australian Academy of Science)
Introducing frog saunas
Research has shown chytrid is worse in winter. My colleagues and I wondered whether, if frogs had access to warmth during winter, could they fight off infection?
The fungus can’t tolerate high temperatures, so if we gave frogs a place to stay warm – even for a few hours a day – perhaps they could survive and recover.
We tested this idea, both in the laboratory and in outdoor experiments.
First we established that endangered green and golden bell frogs will select temperatures that reduce or eliminate chytrid infections, when given the opportunity.
Then we conducted experiments in the lab, with 66 infected frogs. The group given the option of choosing the temperature they liked best rapidly cleared their infection. The group placed in a set, warm temperature also cleared their infection, but it took longer. The low-temperature control group remained infected.
Next, we wanted to see what would happen if frogs that cured infections with heat would still get sick. Or were they immune? The group of 23 heat-cured frogs were 22 times more likely to survive the second infection than the 23 frogs that were heat-treated but not previously infected. So frogs cured with heat acquire resistance to future infections.
Testing frog saunas in the wild
Finally, we wanted to see if this could work in a natural setting. We ran outdoor experiments with 239 frogs. Half were infected with chytrid one week before the experiment began. Then they were placed in enclosures with artificial structures that heat up in the sun, called “frog saunas”. But the frogs could choose from shaded and unshaded areas, with or without saunas.
We found frogs flocked to the sunny saunas, heated up their little bodies, and quickly fought off infection. Think of frog saunas as little factories that pump out healthy, chytrid-resistant frogs.
The frog saunas could be used on a wider scale. We believe they would be best suited to supporting populations of Australian green and golden bell frogs, but they could be useful for other species too.
The saunas are made of inexpensive materials that can be found at your local hardware store, making them accessible to the general public and wildlife managers alike.
We are already building shelters at Sydney Olympic Park, working with Macquarie University and the Sydney Olympic Park Authority. The park is home to one of the largest remaining populations of green and golden bell frogs.
Frog saunas have been set up to support a wild population of frogs in Sydney. Image via Anthony Waddle/ The Conversation.
Want to get involved?
You can become a citizen scientist and help save frogs from extinction. Start by downloading the FrogID app to learn how frogs are faring. Record frog calls with the app for scientists to identify them. This helps provide valuable data for frog conservation.
Build a frog sauna for your backyard, to help keep them healthy through winter.
It’s essentially a brick-filled greenhouse, warmed by sunlight. All you need is some common clay ten-hole masonry bricks, black paint and cable ties – and a little greenhouse to put the sauna inside.
Changing the fate of frogs
Since the discovery of chytrid more than 25 years ago, the pathogen has been a seemingly insurmountable challenge to endangered frog conservation. Now, we have developed a promising, inexpensive and widely applicable strategy to combat chytrid.
Amphibians are such a diverse group that no single approach will be suitable for all species. So this is no silver bullet. But a useful tool for even one threatened or endangered species is cause for optimism.
The concept could also be applied to other wildlife diseases, where differences between the physiology of the host and pathogen can be exploited.
Frogs around the world are being wiped out by a deadly fungus.
The chytrid fungus has caused some 90 frog species to go extinct.
Scientists found “frog saunas” can help warm frogs and fight off the fungus. The frogs didn’t need any encouragement, flocking to the saunas in winter.
You can make a frog sauna with simple materials to help save frogs. Researchers used a masonry brick with holes, veggie greenhouse, black paint and cable ties.
This catastrophic and ongoing biodiversity loss surpasses the devastation wrought by other notorious invasive species such as cats, rats and even cane toads. Short of removing species from the wild and treating them in captivity, few strategies exist to deal with the chytrid threat.
Our new research, published June 26, 2024, in the journal Nature, offers a promising option.
Outbreaks of chytrid (pronounced “KY-trid”) are more common in cold winter months, just like seasonal human flu. We found a way to combat these winter outbreaks using heat. Our purpose-built “frog saunas” allow affected amphibians to warm up and bake off their infections. They are so simple you can build a frog sauna using supplies from the hardware store.
If frogs’ good looks are not enough for you to care about their welfare, perhaps learning how they contribute to the environment or human health will pique your interest.
Frogs eat insects that carry and spread human diseases. Their skin is also a rich source of new medicines that could help us combat antibiotic-resistant superbugs or curb the startling increase in opioid addiction.
Often starting life as a tadpole eating algae, before morphing into a carnivorous adult, frogs carry energy from aquatic ecosystems onto land. There it can be transferred throughout the food web. So losing a single frog species can have serious flow-on effects.
The green and golden bell frog has declined from more than 90% of its former range since the chytrid fungus arrived in Australia. Image via Anthony Waddle/ The Conversation.
The origin and spread of chytrid
It’s likely the chytrid fungus originated in Asia. The pathogen there seems to coexist with native amphibians. But chytrid is deadly elsewhere, possibly because other frogs have no natural defenses.
Chytrid harms frogs by disrupting the integrity of their skin. It depletes electrolytes needed for heart function. Infected frogs can die of cardiac arrest.
Chytrid has spread worldwide through the trade of amphibians, becoming a seemingly permanent part of ecosystems. As eradicating chytrid from the wild is not possible, we need a way to help frogs battle infection.
Chytrid: the frog-killing fungus, featuring Associate Professor Lee Berger (Australian Academy of Science)
Introducing frog saunas
Research has shown chytrid is worse in winter. My colleagues and I wondered whether, if frogs had access to warmth during winter, could they fight off infection?
The fungus can’t tolerate high temperatures, so if we gave frogs a place to stay warm – even for a few hours a day – perhaps they could survive and recover.
We tested this idea, both in the laboratory and in outdoor experiments.
First we established that endangered green and golden bell frogs will select temperatures that reduce or eliminate chytrid infections, when given the opportunity.
Then we conducted experiments in the lab, with 66 infected frogs. The group given the option of choosing the temperature they liked best rapidly cleared their infection. The group placed in a set, warm temperature also cleared their infection, but it took longer. The low-temperature control group remained infected.
Next, we wanted to see what would happen if frogs that cured infections with heat would still get sick. Or were they immune? The group of 23 heat-cured frogs were 22 times more likely to survive the second infection than the 23 frogs that were heat-treated but not previously infected. So frogs cured with heat acquire resistance to future infections.
Testing frog saunas in the wild
Finally, we wanted to see if this could work in a natural setting. We ran outdoor experiments with 239 frogs. Half were infected with chytrid one week before the experiment began. Then they were placed in enclosures with artificial structures that heat up in the sun, called “frog saunas”. But the frogs could choose from shaded and unshaded areas, with or without saunas.
We found frogs flocked to the sunny saunas, heated up their little bodies, and quickly fought off infection. Think of frog saunas as little factories that pump out healthy, chytrid-resistant frogs.
The frog saunas could be used on a wider scale. We believe they would be best suited to supporting populations of Australian green and golden bell frogs, but they could be useful for other species too.
The saunas are made of inexpensive materials that can be found at your local hardware store, making them accessible to the general public and wildlife managers alike.
We are already building shelters at Sydney Olympic Park, working with Macquarie University and the Sydney Olympic Park Authority. The park is home to one of the largest remaining populations of green and golden bell frogs.
Frog saunas have been set up to support a wild population of frogs in Sydney. Image via Anthony Waddle/ The Conversation.
Want to get involved?
You can become a citizen scientist and help save frogs from extinction. Start by downloading the FrogID app to learn how frogs are faring. Record frog calls with the app for scientists to identify them. This helps provide valuable data for frog conservation.
Build a frog sauna for your backyard, to help keep them healthy through winter.
It’s essentially a brick-filled greenhouse, warmed by sunlight. All you need is some common clay ten-hole masonry bricks, black paint and cable ties – and a little greenhouse to put the sauna inside.
Changing the fate of frogs
Since the discovery of chytrid more than 25 years ago, the pathogen has been a seemingly insurmountable challenge to endangered frog conservation. Now, we have developed a promising, inexpensive and widely applicable strategy to combat chytrid.
Amphibians are such a diverse group that no single approach will be suitable for all species. So this is no silver bullet. But a useful tool for even one threatened or endangered species is cause for optimism.
The concept could also be applied to other wildlife diseases, where differences between the physiology of the host and pathogen can be exploited.
This chart shows the 3 stars of the Summer Triangle, in the east in the evening in July. Note Vega’s constellation, Lyra. The Summer Triangle is big! A 12-inch (1/3-meter) ruler, placed at an arm’s length from your eye, will span the approximate distance from Vega to the star Altair. And an outstretched hand will fill the gap between Vega and Deneb. You can see the Summer Triangle in the evening from around May through the end of every year.
The Summer Triangle
On July evenings, look eastward in the evening for the season’s signature star pattern. It’s an asterism called the Summer Triangle, and, as you might guess, it consists of three stars: blue-white Vega, distant Deneb and fast-spinning Altair.
They’re the first three stars to light up the eastern half of the sky after sunset. You can see them even from light-polluted cities, or on a moonlit night.
Watch for the Summer Triangle pattern in the evening beginning around June, through the end of each year.
Vega is bright and blue-white
Blue-white Vega shines brightest of the three stars in the Summer Triangle. It’s the brightest star in the east in the evening on July evenings. And it’s the brightest light in the constellation Lyra the Harp. Thus Vega is also known as Alpha Lyrae. It shines at magnitude +0.03.
Vega is located about 25 light-years away from us. Many people recognize Vega’s constellation, Lyra. This pattern of stars looks like a triangle of stars connected to a parallelogram.
Skywatchers around the world have a special place in their hearts for the beautiful blue-white star, Vega. Come to know it, and you will see why.
How to see Vega and its constellation
Observers in the Northern Hemisphere typically begin noticing Vega in the evening around May, when this star comes into view in the northeast in mid-evening. Throughout northern summer, Vega shines brightly in the east in the evening. It’s high overhead on northern autumn evenings, and in the northwest by December evenings.
The little constellation Lyra has some interesting features. Near Vega you can see Epsilon Lyrae, which telescope users know as a famous double-double star. In other words, through small telescopes, you can see Epsilon Lyrae as double, with each of the two components also a double star.
Meanwhile, another famous telescopic sight lies between the Gamma and Beta stars in Lyra, the Ring Nebula, also called M57.
You can see Vega, Epsilon Lyrae and M57 (the Ring Nebula) marked on the chart below.
The constellation Lyra the Harp, a triangle plus a parallelogram with Vega as the brightest star. We’ve marked some other noteworthy objects in this constellation, too. Notice Epsilon Lyrae, a double-double star, really 5 stars in all. And notice the location of M57, also called the Ring Nebula.
Science of the star Vega
Vega is the fifth-brightest star visible from Earth, and the third-brightest easily visible from mid-northern latitudes, after Sirius and Arcturus. At about 25 light-years away, it is the sixth-closest of all the bright stars, or fifth if you exclude Alpha Centauri, which most of the Northern Hemisphere can’t easily see.
The star’s distinct blue color indicates a surface temperature of nearly 17,000 degrees Fahrenheit (9,400 Celsius), which is is about 7,000 degrees F (4,000 C) hotter than our sun. Vega’s diameter is roughly 2.5 times the diameter of the sun, and it has about twice its mass. But Vega’s internal pressures and temperatures, far greater than our sun’s, will cause it to burn its internal fuel faster. At only half a billion years old, Vega is already middle-aged. That’s in contrast to our middle-aged sun, which is 4 1/2 billion years old. Vega is only about a tenth our sun’s age, but it will run out of fuel in only another half-billion years.
In astronomer-speak, Vega is an “A0V main sequence star.” The “A0” signifies its temperature, whereas the “V” is a measure of energy output (luminosity), indicating that Vega is a normal star (not a giant). “Main sequence” means it’s in the category of normal stars, and produces energy through stable fusion of hydrogen into helium. With a visual magnitude of +0.03 (apparent brightness), Vega appears only marginally dimmer than Arcturus, but with a distinctly different, cool-blue color.
Vega rotates so fast it’s flattened
Vega rotates rapidly, making a single full rotation about its axis once about every 12.5 hours. In contrast, our sun requires 27 days to spin once. As a result, if you could visit Vega in space, you’d find it noticeably flattened, as shown in the computer simulation below. Though a fast spinner, Vega isn’t the fastest of the three Summer Triangle stars. Altair rotates once in only about 10 hours!
This artist’s concept contrasts Vega with our own Sun. It rotates so fast that, if you could see it close-up, the star would appear flattened. Image via Aufdenberg/ NOAO/ AURA/ NSF.
Vega appears to have an asteroid belt
In 2018, astronomers announced it appears Vega has a large asteroid belt surrounding it. NASA’s Spitzer Space Telescope and the European Space Agency’s Herschel Space Observatory detected a ring of warm, rocky debris. NASA said:
In this diagram, the Vega system, which was already known to have a cooler outer belt of comets (orange), is compared to our solar system with its asteroid and Kuiper belts. The relative size of our solar system compared to Vega is illustrated by the small drawing in the middle. On the right, our solar system is scaled up four times.
The comparison illustrates that both systems have inner and outer belts with similar proportions. The gap between the inner and outer debris belts in both systems works out to a ratio of about 1-to-10, with the outer belt 10 times farther away from its host star than the inner belt.
Astronomers think that the gap in the Vega system might contain planets, as is the case in our solar system.
Illustration of a possible asteroid belt (shown here as warm inner belt) around the star Vega. The outer cool belt might be comets. Also, this shows the Vega system in comparison to our solar system enlarged 4 times and to scale. Image via NASA / JPL.
In tradition and myth
In western skylore, Vega’s constellation Lyra was a harp played by the legendary Greek musician Orpheus. According to legend, when Orpheus played his harp, neither god nor mortal could turn away.
In western culture, Vega is known as the Harp Star.
But Asia has the most beautiful stories relating to Vega. In China, the legend speaks of a forbidden romance between the goddess Zhinü – represented by Vega – and a humble farm boy, Niulang, represented by the star Altair. Separated in the night sky by the Milky Way, or Celestial River, the two lovers may meet only once a year. It’s said that their meeting comes on the 7th night of the 7th moon, when a bridge of magpies forms across the Celestial River, and the two lovers briefly reunite.
In Japan, the Tanabata festival features Orihime, a celestial princess or goddess, represented by Vega, who falls in love with a mortal, Hikoboshi, represented by the star Altair. However, this enrages Orihime’s father so he forbids her to see this mere mortal. Then … you know the story. The gods place the two lovers in the sky, separated by the Celestial River or Milky Way. Yet the sky gods in kindness let them reunite on the 7th night of the 7th moon each year. Sometimes Hikoboshi’s annual trip across the Celestial River is treacherous, though, and he doesn’t make it. In that case, Orihime’s tears form raindrops that fall over Japan.
Many Japanese celebrations of Tanabata occur in July, but sometimes they take place in August. Sometimes the Perseid meteor shower represents Orihime’s tears in myth.
For observation, Vega’s position is RA: 18h 36m 56.3s, dec: +38° 47′ 1.3″.
Bottom line: The star Vega in the constellation Lyra is one of the sky’s most beloved stars, for people around the world.
This chart shows the 3 stars of the Summer Triangle, in the east in the evening in July. Note Vega’s constellation, Lyra. The Summer Triangle is big! A 12-inch (1/3-meter) ruler, placed at an arm’s length from your eye, will span the approximate distance from Vega to the star Altair. And an outstretched hand will fill the gap between Vega and Deneb. You can see the Summer Triangle in the evening from around May through the end of every year.
The Summer Triangle
On July evenings, look eastward in the evening for the season’s signature star pattern. It’s an asterism called the Summer Triangle, and, as you might guess, it consists of three stars: blue-white Vega, distant Deneb and fast-spinning Altair.
They’re the first three stars to light up the eastern half of the sky after sunset. You can see them even from light-polluted cities, or on a moonlit night.
Watch for the Summer Triangle pattern in the evening beginning around June, through the end of each year.
Vega is bright and blue-white
Blue-white Vega shines brightest of the three stars in the Summer Triangle. It’s the brightest star in the east in the evening on July evenings. And it’s the brightest light in the constellation Lyra the Harp. Thus Vega is also known as Alpha Lyrae. It shines at magnitude +0.03.
Vega is located about 25 light-years away from us. Many people recognize Vega’s constellation, Lyra. This pattern of stars looks like a triangle of stars connected to a parallelogram.
Skywatchers around the world have a special place in their hearts for the beautiful blue-white star, Vega. Come to know it, and you will see why.
How to see Vega and its constellation
Observers in the Northern Hemisphere typically begin noticing Vega in the evening around May, when this star comes into view in the northeast in mid-evening. Throughout northern summer, Vega shines brightly in the east in the evening. It’s high overhead on northern autumn evenings, and in the northwest by December evenings.
The little constellation Lyra has some interesting features. Near Vega you can see Epsilon Lyrae, which telescope users know as a famous double-double star. In other words, through small telescopes, you can see Epsilon Lyrae as double, with each of the two components also a double star.
Meanwhile, another famous telescopic sight lies between the Gamma and Beta stars in Lyra, the Ring Nebula, also called M57.
You can see Vega, Epsilon Lyrae and M57 (the Ring Nebula) marked on the chart below.
The constellation Lyra the Harp, a triangle plus a parallelogram with Vega as the brightest star. We’ve marked some other noteworthy objects in this constellation, too. Notice Epsilon Lyrae, a double-double star, really 5 stars in all. And notice the location of M57, also called the Ring Nebula.
Science of the star Vega
Vega is the fifth-brightest star visible from Earth, and the third-brightest easily visible from mid-northern latitudes, after Sirius and Arcturus. At about 25 light-years away, it is the sixth-closest of all the bright stars, or fifth if you exclude Alpha Centauri, which most of the Northern Hemisphere can’t easily see.
The star’s distinct blue color indicates a surface temperature of nearly 17,000 degrees Fahrenheit (9,400 Celsius), which is is about 7,000 degrees F (4,000 C) hotter than our sun. Vega’s diameter is roughly 2.5 times the diameter of the sun, and it has about twice its mass. But Vega’s internal pressures and temperatures, far greater than our sun’s, will cause it to burn its internal fuel faster. At only half a billion years old, Vega is already middle-aged. That’s in contrast to our middle-aged sun, which is 4 1/2 billion years old. Vega is only about a tenth our sun’s age, but it will run out of fuel in only another half-billion years.
In astronomer-speak, Vega is an “A0V main sequence star.” The “A0” signifies its temperature, whereas the “V” is a measure of energy output (luminosity), indicating that Vega is a normal star (not a giant). “Main sequence” means it’s in the category of normal stars, and produces energy through stable fusion of hydrogen into helium. With a visual magnitude of +0.03 (apparent brightness), Vega appears only marginally dimmer than Arcturus, but with a distinctly different, cool-blue color.
Vega rotates so fast it’s flattened
Vega rotates rapidly, making a single full rotation about its axis once about every 12.5 hours. In contrast, our sun requires 27 days to spin once. As a result, if you could visit Vega in space, you’d find it noticeably flattened, as shown in the computer simulation below. Though a fast spinner, Vega isn’t the fastest of the three Summer Triangle stars. Altair rotates once in only about 10 hours!
This artist’s concept contrasts Vega with our own Sun. It rotates so fast that, if you could see it close-up, the star would appear flattened. Image via Aufdenberg/ NOAO/ AURA/ NSF.
Vega appears to have an asteroid belt
In 2018, astronomers announced it appears Vega has a large asteroid belt surrounding it. NASA’s Spitzer Space Telescope and the European Space Agency’s Herschel Space Observatory detected a ring of warm, rocky debris. NASA said:
In this diagram, the Vega system, which was already known to have a cooler outer belt of comets (orange), is compared to our solar system with its asteroid and Kuiper belts. The relative size of our solar system compared to Vega is illustrated by the small drawing in the middle. On the right, our solar system is scaled up four times.
The comparison illustrates that both systems have inner and outer belts with similar proportions. The gap between the inner and outer debris belts in both systems works out to a ratio of about 1-to-10, with the outer belt 10 times farther away from its host star than the inner belt.
Astronomers think that the gap in the Vega system might contain planets, as is the case in our solar system.
Illustration of a possible asteroid belt (shown here as warm inner belt) around the star Vega. The outer cool belt might be comets. Also, this shows the Vega system in comparison to our solar system enlarged 4 times and to scale. Image via NASA / JPL.
In tradition and myth
In western skylore, Vega’s constellation Lyra was a harp played by the legendary Greek musician Orpheus. According to legend, when Orpheus played his harp, neither god nor mortal could turn away.
In western culture, Vega is known as the Harp Star.
But Asia has the most beautiful stories relating to Vega. In China, the legend speaks of a forbidden romance between the goddess Zhinü – represented by Vega – and a humble farm boy, Niulang, represented by the star Altair. Separated in the night sky by the Milky Way, or Celestial River, the two lovers may meet only once a year. It’s said that their meeting comes on the 7th night of the 7th moon, when a bridge of magpies forms across the Celestial River, and the two lovers briefly reunite.
In Japan, the Tanabata festival features Orihime, a celestial princess or goddess, represented by Vega, who falls in love with a mortal, Hikoboshi, represented by the star Altair. However, this enrages Orihime’s father so he forbids her to see this mere mortal. Then … you know the story. The gods place the two lovers in the sky, separated by the Celestial River or Milky Way. Yet the sky gods in kindness let them reunite on the 7th night of the 7th moon each year. Sometimes Hikoboshi’s annual trip across the Celestial River is treacherous, though, and he doesn’t make it. In that case, Orihime’s tears form raindrops that fall over Japan.
Many Japanese celebrations of Tanabata occur in July, but sometimes they take place in August. Sometimes the Perseid meteor shower represents Orihime’s tears in myth.
For observation, Vega’s position is RA: 18h 36m 56.3s, dec: +38° 47′ 1.3″.
Bottom line: The star Vega in the constellation Lyra is one of the sky’s most beloved stars, for people around the world.
