Barnard’s Star has 1 planet, maybe more, at last!

Chart showing nearest stars to the sun, with an arrow pointing to Barnard's Star.
Our sun’s closest neighbors among the stars, including Barnard’s Star. Image via NASA PhotoJournal.
  • Barnard’s star is the closest single star to our sun, at only 6 light-years away. For decades, astronomers have been saying it might have a planet. Now a planet has been found.
  • There’s at least one planet orbiting Barnard’s star, an international team of astronomers has confirmed. The confirmed planet is about half the mass of Venus and orbits very close to its star, with a “year” only three days long.
  • And there might be at least three more planets orbiting Barnard’s star. That’s super exciting, because Barnard’s Star is so nearby!

More exciting news! EarthSky has received a $50,000 gift, with a request that it be used to collect matching funds. It’s time to make good on our obligation to match. Click here to donate to EarthSky!

A confirmed planet for Barnard’s Star

Barnard’s star is the closest single star to our sun, only 6 light-years away. Yes, the Alpha Centauri system is closer. But it consists of at least two and probably three stars. Despite being so nearby – and despite decades of speculation – astronomers had not yet confirmed a planet obiting Barnard’s Star. But now, we know it has at least one. An international team of astronomers using the European Southern Observatory’s Very Large Telescope (VLT) in Chile said on October 1, 2024, that they have confirmed a planet about half the mass of Venus. The planet, dubbed Barnard b, completes an orbit around the red dwarf star in only 3.15 Earth days.

The researchers published the peer-reviewed discovery in the journal Astronomy & Astrophysics on October 1, 2024.

Barnard’s Star in popular culture

Why is a planet for Barnard’s Star so exciting? The star is nearby. And it’s single, like our sun. As long ago as the 1960s and ’70s – long before successful planet-hunters like the Kepler spacecraft – there were suggestions that Barnard’s Star might have a family of planets. At that time, reported discrepancies in the motion of the star led to a claim that at least one Jupiter-size planet, and possibly several planets, orbit it. But later evidence disputed the claim.

Then, in November 2018, an international team of astronomers announced it was “99 percent confident” that a planet for Barnard’s Star had been found. Yet that discovery, too, seemed to evaporate when, in 2021, additional work refuted the existence of this planet.

The long-standing rumor of planets for Barnard’s Star secured this star’s place in science fiction. It’s featured in, for example, “The Hitchhiker’s Guide to the Galaxy” by Douglas Adams; “The Garden of Rama” by Arthur C. Clarke and Gentry Lee; and several novels of physicist Robert L. Forward. In these works, the fictional planets of Barnard’s Star are locations for early colonization or way-stations for exploration further into the cosmos.

Barnard’s Star also was the hypothetical target of Project Daedalus, a design study by members of the British Interplanetary Society, in which they envisioned an interstellar craft that could reach its destination within a human lifetime.

And Barnard’s Star has been featured in online games.

Clearly, Barnard’s Star captures peoples’ imaginations!

How they confirmed the new planet

Astronomers had made a tentative detection of a small planet around Barnard’s star back in 2018, orbiting once every 233 days, but it was never confirmed. The astronomers emphasize that the newly discovered exoplanet is not the same as the 2018 candidate.

The discovery comes after five years of observations with the Very Large Telescope at Paranal Observatory in Chile. The new observations were worth it, these astronomers said. Lead author Jonay González Hernández at the Institute of Astrophysics of the Canary Islands in Spain, explained:

Even if it took a long time, we were always confident that we could find something.

The astronomers were looking for possible planets in or close to the habitable zone around Barnard’s star. That’s the distance where temperatures could allow liquid water to exist.

Such planets are easier to find around red dwarf stars – and indeed seem to be common – since those stars are less bright than stars like our sun.


Discovery of the 1st known exoplanet orbiting Barnard’s star. Video via ESO.

It’s hot, hot, hot!

Barnard b is a bit too close to its star to be habitable by earthly standards, however. It orbits its star 20 times closer than Mercury orbits the sun. It takes only 3.15 days to orbit the star. Even though Barnard’s star is a lot cooler than the sun, that is still too close for comfort. Barnard b has an estimated surface temperature of 257 degrees Fahrenheit (125 C). As Hernández noted:

Barnard b is one of the lowest-mass exoplanets known and one of the few known with a mass less than that of Earth. But the planet is too close to the host star, closer than the habitable zone. Even if the star is about 2,500 degrees cooler than our sun, it is too hot there to maintain liquid water on the surface.

The researchers used an instrument on the telescope called ESPRESSO to find the planet. ESPRESSO detects exoplanets using the radial velocity method. In this method, a telescope measures the tiny “wobble” a star makes as the planets’ gravitational pull tugs at the star. In addition, three other instruments elsewhere helped to confirm the planet: HARPS at ESO’s La Silla Observatory, HARPS-N and CARMENES.


Animation of a sub-Earth-mass planet orbiting Barnard’s star. Video via ESO/ M. Kornmesser.

More planets?

Intriguingly, there may be more planets in the Barnard’s star system as well. The research team found hints of at least three more planets orbiting Barnard’s star. These, however, will require more observations to confirm if they really are planets. Co-author Alejandro Suárez Mascareño, also at the Institute of Astrophysics of the Canary Islands, said:

We now need to continue observing this star to confirm the other candidate signals. But the discovery of this planet, along with other previous discoveries such as Proxima b and d, shows that our cosmic backyard is full of low-mass planets.

The paper stated:

Confirming the presence of a compact four-planet system orbiting Barnard’s star, similar to other planetary systems orbiting nearby stars, would require many more ESPRESSO observations.

The discovery, along with other planets – both small and large – around other nearby stars, shows that smaller rocky worlds are common in our galaxy. Could any of them support life? We don’t know yet, but the more we find, the closer we get to answering the long-standing question: “Are we alone?”

Barnard's star: Brownish rocky planet with bright reddish sun above it in the distance.
View larger. | Artist’s concept of the newly discovered exoplanet orbiting Barnard’s star, only 6 light-years away. The planet is about half the mass of Venus with an estimated temperature of 257 degrees Fahrenheit (125 C). There is also tentative evidence for possibly 3 more planets as well. Image via ESO/ M. Kornmesser.

Bottom line: Astronomers have confirmed a small exoplanet orbiting Barnard’s star, the closest single star to our sun. There are hints of at least 3 more planets as well.

Source: A sub-Earth-mass planet orbiting Barnard’s star

Via ESO

Read more: The enduring mystique of Barnard’s Star

Read more: Primitive life at Barnard’s Star?

The post Barnard’s Star has 1 planet, maybe more, at last! first appeared on EarthSky.



from EarthSky https://ift.tt/2HKUodQ
Chart showing nearest stars to the sun, with an arrow pointing to Barnard's Star.
Our sun’s closest neighbors among the stars, including Barnard’s Star. Image via NASA PhotoJournal.
  • Barnard’s star is the closest single star to our sun, at only 6 light-years away. For decades, astronomers have been saying it might have a planet. Now a planet has been found.
  • There’s at least one planet orbiting Barnard’s star, an international team of astronomers has confirmed. The confirmed planet is about half the mass of Venus and orbits very close to its star, with a “year” only three days long.
  • And there might be at least three more planets orbiting Barnard’s star. That’s super exciting, because Barnard’s Star is so nearby!

More exciting news! EarthSky has received a $50,000 gift, with a request that it be used to collect matching funds. It’s time to make good on our obligation to match. Click here to donate to EarthSky!

A confirmed planet for Barnard’s Star

Barnard’s star is the closest single star to our sun, only 6 light-years away. Yes, the Alpha Centauri system is closer. But it consists of at least two and probably three stars. Despite being so nearby – and despite decades of speculation – astronomers had not yet confirmed a planet obiting Barnard’s Star. But now, we know it has at least one. An international team of astronomers using the European Southern Observatory’s Very Large Telescope (VLT) in Chile said on October 1, 2024, that they have confirmed a planet about half the mass of Venus. The planet, dubbed Barnard b, completes an orbit around the red dwarf star in only 3.15 Earth days.

The researchers published the peer-reviewed discovery in the journal Astronomy & Astrophysics on October 1, 2024.

Barnard’s Star in popular culture

Why is a planet for Barnard’s Star so exciting? The star is nearby. And it’s single, like our sun. As long ago as the 1960s and ’70s – long before successful planet-hunters like the Kepler spacecraft – there were suggestions that Barnard’s Star might have a family of planets. At that time, reported discrepancies in the motion of the star led to a claim that at least one Jupiter-size planet, and possibly several planets, orbit it. But later evidence disputed the claim.

Then, in November 2018, an international team of astronomers announced it was “99 percent confident” that a planet for Barnard’s Star had been found. Yet that discovery, too, seemed to evaporate when, in 2021, additional work refuted the existence of this planet.

The long-standing rumor of planets for Barnard’s Star secured this star’s place in science fiction. It’s featured in, for example, “The Hitchhiker’s Guide to the Galaxy” by Douglas Adams; “The Garden of Rama” by Arthur C. Clarke and Gentry Lee; and several novels of physicist Robert L. Forward. In these works, the fictional planets of Barnard’s Star are locations for early colonization or way-stations for exploration further into the cosmos.

Barnard’s Star also was the hypothetical target of Project Daedalus, a design study by members of the British Interplanetary Society, in which they envisioned an interstellar craft that could reach its destination within a human lifetime.

And Barnard’s Star has been featured in online games.

Clearly, Barnard’s Star captures peoples’ imaginations!

How they confirmed the new planet

Astronomers had made a tentative detection of a small planet around Barnard’s star back in 2018, orbiting once every 233 days, but it was never confirmed. The astronomers emphasize that the newly discovered exoplanet is not the same as the 2018 candidate.

The discovery comes after five years of observations with the Very Large Telescope at Paranal Observatory in Chile. The new observations were worth it, these astronomers said. Lead author Jonay González Hernández at the Institute of Astrophysics of the Canary Islands in Spain, explained:

Even if it took a long time, we were always confident that we could find something.

The astronomers were looking for possible planets in or close to the habitable zone around Barnard’s star. That’s the distance where temperatures could allow liquid water to exist.

Such planets are easier to find around red dwarf stars – and indeed seem to be common – since those stars are less bright than stars like our sun.


Discovery of the 1st known exoplanet orbiting Barnard’s star. Video via ESO.

It’s hot, hot, hot!

Barnard b is a bit too close to its star to be habitable by earthly standards, however. It orbits its star 20 times closer than Mercury orbits the sun. It takes only 3.15 days to orbit the star. Even though Barnard’s star is a lot cooler than the sun, that is still too close for comfort. Barnard b has an estimated surface temperature of 257 degrees Fahrenheit (125 C). As Hernández noted:

Barnard b is one of the lowest-mass exoplanets known and one of the few known with a mass less than that of Earth. But the planet is too close to the host star, closer than the habitable zone. Even if the star is about 2,500 degrees cooler than our sun, it is too hot there to maintain liquid water on the surface.

The researchers used an instrument on the telescope called ESPRESSO to find the planet. ESPRESSO detects exoplanets using the radial velocity method. In this method, a telescope measures the tiny “wobble” a star makes as the planets’ gravitational pull tugs at the star. In addition, three other instruments elsewhere helped to confirm the planet: HARPS at ESO’s La Silla Observatory, HARPS-N and CARMENES.


Animation of a sub-Earth-mass planet orbiting Barnard’s star. Video via ESO/ M. Kornmesser.

More planets?

Intriguingly, there may be more planets in the Barnard’s star system as well. The research team found hints of at least three more planets orbiting Barnard’s star. These, however, will require more observations to confirm if they really are planets. Co-author Alejandro Suárez Mascareño, also at the Institute of Astrophysics of the Canary Islands, said:

We now need to continue observing this star to confirm the other candidate signals. But the discovery of this planet, along with other previous discoveries such as Proxima b and d, shows that our cosmic backyard is full of low-mass planets.

The paper stated:

Confirming the presence of a compact four-planet system orbiting Barnard’s star, similar to other planetary systems orbiting nearby stars, would require many more ESPRESSO observations.

The discovery, along with other planets – both small and large – around other nearby stars, shows that smaller rocky worlds are common in our galaxy. Could any of them support life? We don’t know yet, but the more we find, the closer we get to answering the long-standing question: “Are we alone?”

Barnard's star: Brownish rocky planet with bright reddish sun above it in the distance.
View larger. | Artist’s concept of the newly discovered exoplanet orbiting Barnard’s star, only 6 light-years away. The planet is about half the mass of Venus with an estimated temperature of 257 degrees Fahrenheit (125 C). There is also tentative evidence for possibly 3 more planets as well. Image via ESO/ M. Kornmesser.

Bottom line: Astronomers have confirmed a small exoplanet orbiting Barnard’s star, the closest single star to our sun. There are hints of at least 3 more planets as well.

Source: A sub-Earth-mass planet orbiting Barnard’s star

Via ESO

Read more: The enduring mystique of Barnard’s Star

Read more: Primitive life at Barnard’s Star?

The post Barnard’s Star has 1 planet, maybe more, at last! first appeared on EarthSky.



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Are the Andromeda and Milky Way galaxies already merging?

Oblique view of a large white disk-shaped nebula with bright reddish spots, dark lanes and thousands of foreground stars.
View at EarthSky Community Photos. | Jeremy Likness in Newport, Oregon, captured this telescopic view of the Andromeda galaxy on July 9, 2024. Jeremy wrote: “It’s a galaxy so near it could be interacting with our stars. It’s so big and bright that you can photograph it with an ordinary camera. The Andromeda galaxy, named for the constellation it hangs out in, is located just off the edge of the distinct ‘W’ of Cassiopeia. I used a hydrogen-alpha filter to find the red emissions hanging out in the limbs of this barred spiral galaxy that is our neighbor.” Thank you, Jeremy!

Super-fast stars from Andromeda may already be here

Could stars flung out of the nearby Andromeda galaxy already be tearing through the Milky Way?

Probably, yes, a group of astronomers said on March 12, 2024. After sifting through data from the Gaia probe, they hypothesized that some of the fastest stars speeding through the Milky Way might come from outside it.

While the researchers aren’t certain, exploration of this intriguing possibility goes on. The group – astrophysicists Lukas Gülzow, Malcolm Fairbairn and Dominik J. Schwarz – focused on extremely fast moving stars in our galaxy. These hypervelocity stars are from the fastest class of stellar object known. The first one discovered back in 1988 moves 1.5 million mph (2.4 million kph). That’s about 430 miles (700 km) a second!

To find out if they’re right, the trio built themselves a couple of galaxies, in a computer, of course:

Therefore, we simulate hypervelocity stars originating in Andromeda with initial conditions based on attributes of high-velocity stars measured in the Milky Way and a simple model for the gravitational potential of Andromeda and the Milky Way.

Gravitational potential is the amount of energy needed to move an object. The peer-reviewed Monthly Notices of the Royal Astronomical Society published their results in the April 2024 issue.

Ready to make a cosmic impact? Help us achieve our $50,000 match goal by donating today!

Andromeda is on a crash course with us!

Andromeda – a galaxy bigger than our own – is heading right for us. For each tick of the clock, it gets 70 miles closer. But don’t freak out yet.

The bulks of the Milky Way and Andromeda are still about 2.5 million light-years apart. That means these big members of our cosmic neighborhood – the Local Group – won’t really start mixing together for another 5 billion years. And that makes it something to worry about later.

Except the merger is technically already happening. Sort of. Research published in 2022 suggests the galactic halos are already touching. Galactic halos are spheres of stars, dust and dark matter that surround many, if not most, galaxies.

And they’re big. The Milky Way’s galactic halo is at least 2 million light years across. Larger Andromeda’s halo is about the same size, but lumpy.

If stars from Andromeda are inside the Milky Way – and vice versa – it’s more evidence the merger really is underway now.

Night sky with huge, bright oblique swirl of stars - Andromeda galaxy - next to cloudy band of Milky Way.
Artist’s concept of Earth’s night sky as the Andromeda galaxy approaches the Milky Way. Image via NASA/ ESA/ Z. Levay and R. van der Marel, STScI/ T. Hallas/ A. Mellinger.

How many neighboring stars are already in the Milky Way?

Since the first hypervelocity star was discovered back in 1988, several others have been detected inside the Milky Way. The question is: How many of them came from outside the galaxy? More specifically, how many are from Andromeda? It could be a handful. It could be thousands, the researchers said:

While we expect that the vast majority of hypervelocity stars in our galaxy will originate here, we expect the number of stars present from Andromeda at any one time to be between 12 and 3,910, depending upon model assumptions.

And why are they moving so mindbogglingly fast? The paper provides the current best guess:

The cause for such high kinetic energies is thought to be gravitational interactions between binary stars and the supermassive black hole in the Milky Way Center or other massive black holes in that region.

So sometimes a pair of stars gets too close to the monstrously large black hole in a galactic core. Then one of the stars gains enough velocity to fling out of its orbit. The other is captured by the black hole. The amount of momentum involved pushes the escapees to millions of miles or kilometers a second. This is like the gravitational slingshot technique used to speed up spacecraft in the solar system. The probes pass near large planets, like Jupiter, and pick up speed toward their final destinations.

When this happens with stars, it’s known as the Hills mechanism.

ID’ing stars from the Andromeda galaxy

According to the researchers, their models show some hypervelocity stars in our galaxy could have originated in Andromeda. They said:

We found that it is possible for them to reach the Milky Way. We approximated the amount of Andromeda hypervelocity stars in the Milky Way at the present time and analyzed their position and velocity properties. In addition, we discuss whether it is possible to detect them.

Possible isn’t the same as actual. The researchers needed to know the path hypervelocity stars followed to reach their current positions. This is how they did it. They began by looking for stuck hypervelocity stars:

To start with, we find that many hypervelocity stars at lower velocities are not fast enough to be able to escape the Milky Way again. Thus, a significant fraction of the hypervelocity stars arriving from Andromeda remain bound to the Milky Way gravity.

The group then compared their simulations to real data:

To assess whether hypervelocity stars from Andromeda reaching the Milky Way is ruled out by observations, we compare the simulated HVSs at present time with star data from the Gaia DR3.

Gaia is a European probe studying the distribution of stars in the Milky Way. The DR3 is the 3rd data release of Gaia’s observations. It came out in June 2022.

At least 10 stars from Andromeda should be here

So are stars traveling as fast as is possible already arriving from Andromeda? The researchers said yes, they are, or really, really should be:

We have compared the velocity directions from the simulation results with the Gaia data to find an approximately homogeneous population of velocity directions that overlaps with the simulated velocity directions.

The models said there must be at least 10 of them in the Milky Way, or even possibly thousands. We just don’t know yet. But we do know what to look for, said authors Gülzow, Fairbairn and Schwarz:

It might be possible to detect them based on their velocity and trajectory orientation. Further, it would be interesting to extend this analysis to include estimates of the stellar ages and other astrophysical information of hypervelocity stars in order to gain further insight into their origin and migration history.

Looks like yet another mystery for Gaia to explore.

Bottom line: Researchers studying the fastest stars in the Milky Way galaxy believe some may come from the nearby Andromeda galaxy. This supports the idea the two galaxies are already merging.

Source: On stellar migration from Andromeda to the Milky Way

Read more: The Andromeda galaxy: All you need to know

The post Are the Andromeda and Milky Way galaxies already merging? first appeared on EarthSky.



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Oblique view of a large white disk-shaped nebula with bright reddish spots, dark lanes and thousands of foreground stars.
View at EarthSky Community Photos. | Jeremy Likness in Newport, Oregon, captured this telescopic view of the Andromeda galaxy on July 9, 2024. Jeremy wrote: “It’s a galaxy so near it could be interacting with our stars. It’s so big and bright that you can photograph it with an ordinary camera. The Andromeda galaxy, named for the constellation it hangs out in, is located just off the edge of the distinct ‘W’ of Cassiopeia. I used a hydrogen-alpha filter to find the red emissions hanging out in the limbs of this barred spiral galaxy that is our neighbor.” Thank you, Jeremy!

Super-fast stars from Andromeda may already be here

Could stars flung out of the nearby Andromeda galaxy already be tearing through the Milky Way?

Probably, yes, a group of astronomers said on March 12, 2024. After sifting through data from the Gaia probe, they hypothesized that some of the fastest stars speeding through the Milky Way might come from outside it.

While the researchers aren’t certain, exploration of this intriguing possibility goes on. The group – astrophysicists Lukas Gülzow, Malcolm Fairbairn and Dominik J. Schwarz – focused on extremely fast moving stars in our galaxy. These hypervelocity stars are from the fastest class of stellar object known. The first one discovered back in 1988 moves 1.5 million mph (2.4 million kph). That’s about 430 miles (700 km) a second!

To find out if they’re right, the trio built themselves a couple of galaxies, in a computer, of course:

Therefore, we simulate hypervelocity stars originating in Andromeda with initial conditions based on attributes of high-velocity stars measured in the Milky Way and a simple model for the gravitational potential of Andromeda and the Milky Way.

Gravitational potential is the amount of energy needed to move an object. The peer-reviewed Monthly Notices of the Royal Astronomical Society published their results in the April 2024 issue.

Ready to make a cosmic impact? Help us achieve our $50,000 match goal by donating today!

Andromeda is on a crash course with us!

Andromeda – a galaxy bigger than our own – is heading right for us. For each tick of the clock, it gets 70 miles closer. But don’t freak out yet.

The bulks of the Milky Way and Andromeda are still about 2.5 million light-years apart. That means these big members of our cosmic neighborhood – the Local Group – won’t really start mixing together for another 5 billion years. And that makes it something to worry about later.

Except the merger is technically already happening. Sort of. Research published in 2022 suggests the galactic halos are already touching. Galactic halos are spheres of stars, dust and dark matter that surround many, if not most, galaxies.

And they’re big. The Milky Way’s galactic halo is at least 2 million light years across. Larger Andromeda’s halo is about the same size, but lumpy.

If stars from Andromeda are inside the Milky Way – and vice versa – it’s more evidence the merger really is underway now.

Night sky with huge, bright oblique swirl of stars - Andromeda galaxy - next to cloudy band of Milky Way.
Artist’s concept of Earth’s night sky as the Andromeda galaxy approaches the Milky Way. Image via NASA/ ESA/ Z. Levay and R. van der Marel, STScI/ T. Hallas/ A. Mellinger.

How many neighboring stars are already in the Milky Way?

Since the first hypervelocity star was discovered back in 1988, several others have been detected inside the Milky Way. The question is: How many of them came from outside the galaxy? More specifically, how many are from Andromeda? It could be a handful. It could be thousands, the researchers said:

While we expect that the vast majority of hypervelocity stars in our galaxy will originate here, we expect the number of stars present from Andromeda at any one time to be between 12 and 3,910, depending upon model assumptions.

And why are they moving so mindbogglingly fast? The paper provides the current best guess:

The cause for such high kinetic energies is thought to be gravitational interactions between binary stars and the supermassive black hole in the Milky Way Center or other massive black holes in that region.

So sometimes a pair of stars gets too close to the monstrously large black hole in a galactic core. Then one of the stars gains enough velocity to fling out of its orbit. The other is captured by the black hole. The amount of momentum involved pushes the escapees to millions of miles or kilometers a second. This is like the gravitational slingshot technique used to speed up spacecraft in the solar system. The probes pass near large planets, like Jupiter, and pick up speed toward their final destinations.

When this happens with stars, it’s known as the Hills mechanism.

ID’ing stars from the Andromeda galaxy

According to the researchers, their models show some hypervelocity stars in our galaxy could have originated in Andromeda. They said:

We found that it is possible for them to reach the Milky Way. We approximated the amount of Andromeda hypervelocity stars in the Milky Way at the present time and analyzed their position and velocity properties. In addition, we discuss whether it is possible to detect them.

Possible isn’t the same as actual. The researchers needed to know the path hypervelocity stars followed to reach their current positions. This is how they did it. They began by looking for stuck hypervelocity stars:

To start with, we find that many hypervelocity stars at lower velocities are not fast enough to be able to escape the Milky Way again. Thus, a significant fraction of the hypervelocity stars arriving from Andromeda remain bound to the Milky Way gravity.

The group then compared their simulations to real data:

To assess whether hypervelocity stars from Andromeda reaching the Milky Way is ruled out by observations, we compare the simulated HVSs at present time with star data from the Gaia DR3.

Gaia is a European probe studying the distribution of stars in the Milky Way. The DR3 is the 3rd data release of Gaia’s observations. It came out in June 2022.

At least 10 stars from Andromeda should be here

So are stars traveling as fast as is possible already arriving from Andromeda? The researchers said yes, they are, or really, really should be:

We have compared the velocity directions from the simulation results with the Gaia data to find an approximately homogeneous population of velocity directions that overlaps with the simulated velocity directions.

The models said there must be at least 10 of them in the Milky Way, or even possibly thousands. We just don’t know yet. But we do know what to look for, said authors Gülzow, Fairbairn and Schwarz:

It might be possible to detect them based on their velocity and trajectory orientation. Further, it would be interesting to extend this analysis to include estimates of the stellar ages and other astrophysical information of hypervelocity stars in order to gain further insight into their origin and migration history.

Looks like yet another mystery for Gaia to explore.

Bottom line: Researchers studying the fastest stars in the Milky Way galaxy believe some may come from the nearby Andromeda galaxy. This supports the idea the two galaxies are already merging.

Source: On stellar migration from Andromeda to the Milky Way

Read more: The Andromeda galaxy: All you need to know

The post Are the Andromeda and Milky Way galaxies already merging? first appeared on EarthSky.



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An annular solar eclipse on October 2, 2024

Annular solar eclipse: Orange ring with some little flames coming out ou it.
View at EarthSky Community Photos. | Alan Howell from Albuquerque, New Mexico, took this photo in Mariposa Basin Park during the maximum annular solar eclipse on October 14, 2023, and wrote: “What an incredible adventure! It took months of planning, gear testing, software and equipment training, booking flights and hotels, car traveling, weather forecast monitoring, and location scouting to produce this colorized H-alpha image of the ‘ring of fire’ eclipse, showing prominences.” Thank you, Alan!

Annular solar eclipse October 2, 2024 occurs worldwide

The second solar eclipse of 2024 will be an annular – sometimes called a “ring of fire” – solar eclipse on Wednesday, October 2, 2024. The solar eclipse will be visible from parts of South America, the Pacific Ocean, the Atlantic Ocean, and Antarctica. As you can tell from the map below, most of it will be visible over the ocean.

Below are the times of the annular solar eclipse phases on October 2, 2024:

    Partial eclipse begins at 15:42 UTC
    Annular eclipse begins at 16:50 UTC
    Maximum Eclipse begins at 18:45 UTC
    Annular eclipse ends at 20:39 UTC
    Partial eclipse ends at 21:47 UTC

For precise timing from your location check temeanddate.com.

Globe of the Earth showing path of annular solar eclipse on October 2, 2024.
View larger. | The orange line shows the path of the October 2, 2024, annular solar eclipse. And those farther from the path will see a partial solar eclipse. Image via Fred Espenak. Used with permission.

Click here to learn how to watch a solar eclipse safely.

Animations and seeing the eclipse from your location

Watch an animation of the path of the annular solar eclipse at timeanddate.com.

Another animation of the eclipse at eclipsewise.com

For information from your location timeanddate.com

The Solar Eclipse Circumstances Calculator is an interactive web page

Why is it called an annular eclipse?

Astronomers call this an annular eclipse of the sun. In fact, that name comes from the Latin word for ring: annulus. That’s because it refers to the outer rings of the sun’s surface, visible at mid-eclipse. And, though not as dramatic as a total solar eclipse, this eclipse will be fascinating to view. You really only need to know two things. First, how much of the sun will be covered from your location? Second, what time is the eclipse from your location?

Overall, the eclipse will last 223 minutes. At maximum eclipse – for those along the center eclipse path – the sun will be just over 86 percent covered by the moon. The part of the sun that will be visible is its outer surface. So essentially, an annular eclipse is a partial eclipse, throughout the event. So remember, use eye protection! At no time will this eclipse be safe to view without some form of solar filter protection.

Diagram showing sun, moon, and Earth, with different parts of moon's shadow labeled.
The moon’s umbra and antumbra, surrounded by the penumbra. Image via timeanddate.com. Used with permission.

Overview of the October 2 annular solar eclipse path

The path of the annular eclipse will begin about 1,056 miles (1,700 kilometers) southwest of the Hawaiian Islands at 16:54 UTC. That’s where the moon’s antumbral shadow first falls on Earth forming a 205-mile-wide (331 kilometers) path. And the annular eclipse lasting there for 5 minutes and 39 seconds.

Then the annular eclipse sun will move southwest and reach greatest eclipse at 18:45 UTC with a duration of 7 minutes and 2 seconds over a path 165 miles (266 kilometers) wide. The eclipse magnitude is 0.93 with 0.87 of the sun obscured.

At 19:07 UTC, the annular eclipse will finally reach land when it passes over Rapa Nui. The remote island is 42 miles (68 kilometers) northeast of the central line, but they’ll still have 6 minutes and 23 seconds of the annular eclipse. The next land it reaches is Chile’s Patagonian coast at 20:22 UTC. The central line there is 6 minutes and 26 seconds. Crossing the Andes, the eclipse reaches Argentina at 20:24 UTC. The shadow takes a little over three minutes to cross Argentina before reaching the South Atlantic coast at 20:27 UTC.

Finally, the eclipse will pass north of the Falkland Islands, where the antumbral path ends 341 miles (550 kilometers) north of South Georgia at 20:36 UTC. In the end, the antumbral path will pass over 8,800 miles (14,200 kilometers) in 3 hours and 43 minutes. And it will cover 0.82% of the Earth’s surface area.

Meanwhile, those outside the shadow path will see a partial solar eclipse. Important: this is not a total eclipse. And the first thing to remember, at no time during this eclipse will it be safe to look at the sun without proper eye protection.

This is 2024’s 2nd solar eclipse

The first solar eclipse in 2024 – on April 8, 2024 – was a total solar eclipse whose path of totality passed over North America.

Black circle with fuzzy white rim; bright crescent; thin brilliant ring in fuzzy orange circle.
The appearance of a total solar eclipse (left), partial solar eclipse (middle) and annular solar eclipse (right). The one on the right – the annular eclipse – is what those along the eclipse path will see on Wednesday, October 2. Image via K. Bikos/ timeanddate.com.

Bottom line: The October 2, 2024, annular solar eclipse will cross over parts of South America, the Pacific Ocean, the Atlantic Ocean, and Antarctica.

Read more:

The total solar eclipse of April 8, 2024

Read more by Fred Espenak at EclipseWise.com

The post An annular solar eclipse on October 2, 2024 first appeared on EarthSky.



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Annular solar eclipse: Orange ring with some little flames coming out ou it.
View at EarthSky Community Photos. | Alan Howell from Albuquerque, New Mexico, took this photo in Mariposa Basin Park during the maximum annular solar eclipse on October 14, 2023, and wrote: “What an incredible adventure! It took months of planning, gear testing, software and equipment training, booking flights and hotels, car traveling, weather forecast monitoring, and location scouting to produce this colorized H-alpha image of the ‘ring of fire’ eclipse, showing prominences.” Thank you, Alan!

Annular solar eclipse October 2, 2024 occurs worldwide

The second solar eclipse of 2024 will be an annular – sometimes called a “ring of fire” – solar eclipse on Wednesday, October 2, 2024. The solar eclipse will be visible from parts of South America, the Pacific Ocean, the Atlantic Ocean, and Antarctica. As you can tell from the map below, most of it will be visible over the ocean.

Below are the times of the annular solar eclipse phases on October 2, 2024:

    Partial eclipse begins at 15:42 UTC
    Annular eclipse begins at 16:50 UTC
    Maximum Eclipse begins at 18:45 UTC
    Annular eclipse ends at 20:39 UTC
    Partial eclipse ends at 21:47 UTC

For precise timing from your location check temeanddate.com.

Globe of the Earth showing path of annular solar eclipse on October 2, 2024.
View larger. | The orange line shows the path of the October 2, 2024, annular solar eclipse. And those farther from the path will see a partial solar eclipse. Image via Fred Espenak. Used with permission.

Click here to learn how to watch a solar eclipse safely.

Animations and seeing the eclipse from your location

Watch an animation of the path of the annular solar eclipse at timeanddate.com.

Another animation of the eclipse at eclipsewise.com

For information from your location timeanddate.com

The Solar Eclipse Circumstances Calculator is an interactive web page

Why is it called an annular eclipse?

Astronomers call this an annular eclipse of the sun. In fact, that name comes from the Latin word for ring: annulus. That’s because it refers to the outer rings of the sun’s surface, visible at mid-eclipse. And, though not as dramatic as a total solar eclipse, this eclipse will be fascinating to view. You really only need to know two things. First, how much of the sun will be covered from your location? Second, what time is the eclipse from your location?

Overall, the eclipse will last 223 minutes. At maximum eclipse – for those along the center eclipse path – the sun will be just over 86 percent covered by the moon. The part of the sun that will be visible is its outer surface. So essentially, an annular eclipse is a partial eclipse, throughout the event. So remember, use eye protection! At no time will this eclipse be safe to view without some form of solar filter protection.

Diagram showing sun, moon, and Earth, with different parts of moon's shadow labeled.
The moon’s umbra and antumbra, surrounded by the penumbra. Image via timeanddate.com. Used with permission.

Overview of the October 2 annular solar eclipse path

The path of the annular eclipse will begin about 1,056 miles (1,700 kilometers) southwest of the Hawaiian Islands at 16:54 UTC. That’s where the moon’s antumbral shadow first falls on Earth forming a 205-mile-wide (331 kilometers) path. And the annular eclipse lasting there for 5 minutes and 39 seconds.

Then the annular eclipse sun will move southwest and reach greatest eclipse at 18:45 UTC with a duration of 7 minutes and 2 seconds over a path 165 miles (266 kilometers) wide. The eclipse magnitude is 0.93 with 0.87 of the sun obscured.

At 19:07 UTC, the annular eclipse will finally reach land when it passes over Rapa Nui. The remote island is 42 miles (68 kilometers) northeast of the central line, but they’ll still have 6 minutes and 23 seconds of the annular eclipse. The next land it reaches is Chile’s Patagonian coast at 20:22 UTC. The central line there is 6 minutes and 26 seconds. Crossing the Andes, the eclipse reaches Argentina at 20:24 UTC. The shadow takes a little over three minutes to cross Argentina before reaching the South Atlantic coast at 20:27 UTC.

Finally, the eclipse will pass north of the Falkland Islands, where the antumbral path ends 341 miles (550 kilometers) north of South Georgia at 20:36 UTC. In the end, the antumbral path will pass over 8,800 miles (14,200 kilometers) in 3 hours and 43 minutes. And it will cover 0.82% of the Earth’s surface area.

Meanwhile, those outside the shadow path will see a partial solar eclipse. Important: this is not a total eclipse. And the first thing to remember, at no time during this eclipse will it be safe to look at the sun without proper eye protection.

This is 2024’s 2nd solar eclipse

The first solar eclipse in 2024 – on April 8, 2024 – was a total solar eclipse whose path of totality passed over North America.

Black circle with fuzzy white rim; bright crescent; thin brilliant ring in fuzzy orange circle.
The appearance of a total solar eclipse (left), partial solar eclipse (middle) and annular solar eclipse (right). The one on the right – the annular eclipse – is what those along the eclipse path will see on Wednesday, October 2. Image via K. Bikos/ timeanddate.com.

Bottom line: The October 2, 2024, annular solar eclipse will cross over parts of South America, the Pacific Ocean, the Atlantic Ocean, and Antarctica.

Read more:

The total solar eclipse of April 8, 2024

Read more by Fred Espenak at EclipseWise.com

The post An annular solar eclipse on October 2, 2024 first appeared on EarthSky.



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October birthstone: Colorful opal and tourmaline

October birthstone: Several polished oval opals, primarily white with iridescent blue, green, yellow and red specks.
Polished opals from Australia. The opal is an October birthstone. Image via Sevenopal/ Wikimedia Commons (CC BY-SA 4.0).

October babies have two birthstones to choose from: opal or tourmaline.

Opal, the primary October birthstone

The best known October birthstone is the opal. They’re amazingly diverse rocks, taking on different appearances depending on how they formed. Precious opals, known for their flashy iridescent colors, are popular in some jewelry. But even the less dazzling common opals possess a quiet beauty that makes them popular in specimen collections.

Unlike most other gemstones, opals don’t qualify as minerals in the usual sense. They contain myriads of tiny silica spheres in a tightly-packed lattice. These gemstones are famous for their play of colors. They flash rainbow hues when moved. The colors come from the interference of light with their internal structures.

Opals form in near-surface volcanic rocks, within cavities and cracks. In sedimentary volcanic ash rock, percolating water in the ground dissolves silica that eventually precipitates to form the opal. On rare occasions, it becomes the replacement material for fossils – shells, bones, wood – whose original material had dissolved away.

Characteristics of opals

An opal is a soft stone, easily altered in appearance by changes in heat and pressure. Varying amounts of water within it determine the appearance of the gemstone. When water evaporates out of an opal, the stone appears slightly smaller and the stress of the evaporation creates cracks on it.

Australia mines most of the world’s opals. That’s especially the case for magnificent black opals. Ethiopia is another emerging source of opals. At a smaller scale, a wide variety of opals are found in northern Nevada; some of those opals are in the form of fossilized wood. Other commercial sources of opal are Mexico, Canada, Brazil, Honduras, Nicaragua, Guatemala, Turkey and the Czech Republic.

Impurities within the stones create the characteristic colors of opals. Milky or pearly opals indicate tiny gas bubble inclusions. Yellows and reds indicate iron oxides inclusions. The spectacular black opals that sometimes flash green, blue and red get their color from magnesium oxides and organic carbon within the stone. Perhaps the most valuable opal pattern is the harlequin. It has large angular patches of red, yellow and green resembling the checks on a clown’s costume.

An oval polished opal showing roughly squarish colors of red, yellow, blue and green.
A Harlequin opal. Image via Aisha Brown/ Wikimedia Commons (CC BY-SA 2.0).

Opal lore

The name opal is derived from the Sanskrit word “upala,” as well as the Latin “opalus,” meaning “precious stone.”

The ancient Roman natural historian Pliny the Elder wrote about the captivating iridescence of the opal in his book, The Natural History of Precious Stones.

Of all precious stones, it is opal that presents the greatest difficulties of description, it displaying at once the piercing fire of carbunculus, the purple brilliancy of amethystos, and the sea-green of smaragdus, the whole blended together and refulgent with a brightness that is quite incredible.

There is an Indian legend about the origin of the opal. As Willard Heaps wrote in Gemstones:

… the gods Brahma, Vishnu and Shiva once vied in jealous love for a beautiful woman. This angered the Eternal, who changed the fair mortal into a creature made of mist. Thereupon each of the three gods endowed her with his own color so as to be able to recognize her. Brahma gave her the glorious blue of the heavens, Vishnu enriched her with the splendor of gold and Shiva lent her his flaming red. But all this was in vain, since the lovely phantom was whisked away by the winds. Finally, the Eternal took pity on her and transformed her into a stone, the opal, that sparkles in all the colors of the rainbow.

Heaps also wrote that ancient cultures attached meaning to opals. Romans called opals the Cupid stone. Asians called it the anchor of hope. Arabians believed they fell from the sky. In Poland, People thought that opals made their wearer invisible, hence the opal was the talisman of thieves and spies.

October birthstone: evil superstitions

During the medieval period, a change in color intensity of an opal was believed to indicate if its wearer was ill or in good health. Supposedly the opal maintained a strong heart, prevented fainting, protected against infection and cleansed foul-smelling air. The stone, as in ancient times, still represented a symbol of hope.

But the opal’s reputation changed in the mid-14th century. The Black Death swept across Europe, killing 1/4 of its population. People thought the gem was the cause of death. When worn by someone struck with the deadly plague, it would appear brilliant only until the person died. Then it would change in appearance, losing its luster. In reality, it was the sensitivity of this stone to changes in temperature that altered its appearance, as the heat from a burning fever gave way to the cold of death.

In Elizabethan England, people treasured the opal for its beauty. Shakespeare wrote of it in his play Twelfth Night as the queen of gems. Queen Victoria is said to have loved opals and presented them to her children, thus making the stone popular. But the stone continued to have a mixed reputation, chiefly due to a novel, Anne of Geierstein, written by Sir Walter Scott in 1829 that depicted it as a stone of evil.

In Australia, opals have long been a part of Australian Aboriginal cultures. In one story, set during the Dreamtime, a pelican was resting in an area of beautiful colors. When he pecked at the colored stones, a spark flew out and lit the dry grass on fire. As the fire spread, it reached his people who, for the first time, were able to cook fish and meat.

Tourmaline, an alternate October birthstone

An alternate October birthstone is tourmaline, a gemstone that exhibits the broadest spectrum of gemstone colors. Gem-quality forms of this mineral have in the past been misidentified as rubies, emeralds and sapphires. In fact, a famous tourmaline – the size of a pigeon’s egg – belonging to the Russian empress Catherine the Great, was long thought to be a ruby.

The name of this gemstone is believed to derive from the Singhalese (Sri Lankan) word toramalli, a term applied to colorful stones.

A squarish green linear crystal with an inclusion of some white crystals at the top.
A green elbaite crystal, a type of tourmaline, from Brazil. (The white crystal is the mineral albite.) Image via Ivar Leidus/ Wikimedia Commons (CC BY-SA 4.0).

Tourmaline characteristics

Tourmaline is a complex boron-bearing silicate mineral that can also contain other elements such as aluminum, magnesium, sodium, iron and lithium. They come in a myriad of colors: yellow, green, red, blue, pink, brown and black. Metals within the crystal structure are responsible for the gemstone colors. Pink, for example, comes from the presence of manganese. Iron produces black to deep brown colors, while magnesium creates browns and yellows. Tourmalines rich in lithium can produce several different colors such as blues, greens and reds. Some crystals even have bicolored properties. One variety, called the watermelon tourmaline, has green outer edges that transition to a transparent white zone that gives way to a pink or light red interior.

When tourmalines are warmed or rubbed, they attract small bits of paper, lint and ash. This occurs because the gem becomes charged with static electricity. In fact, Benjamin Franklin used this gem in his studies of electricity. Maintaining a tourmaline exhibit at museums requires frequent cleaning of the gemstone because heat from lights of the display case create a charge in the stone that attracts dust.

Compared with other gemstones, tourmalines are a relatively recent discovery. Hence, it lacks the rich lore that accompanies many other precious gems. However, some people think of tourmaline as the peace stone, believed to dispel fear and make its wearer calm.

Black rectangular tourmaline crystals on white rock, with a small green fluorite crystal.
Schorl is the most commonly found form of tourmaline. In this specimen from Namibia, a small piece of green fluorite is perched atop the tourmaline crystals. Image via Robert M. Lavinsky/ Wikimedia Commons (CC BY-SA 3.0).

Find out about birthstones for the rest of the year

January birthstone
February birthstone
March birthstone
April birthstone
May birthstone
June birthstone
July birthstone
August birthstone
September birthstone
October birthstone
November birthstone
December birthstone

Bottom line: October has two birthstones, opal and tourmaline.

The post October birthstone: Colorful opal and tourmaline first appeared on EarthSky.



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October birthstone: Several polished oval opals, primarily white with iridescent blue, green, yellow and red specks.
Polished opals from Australia. The opal is an October birthstone. Image via Sevenopal/ Wikimedia Commons (CC BY-SA 4.0).

October babies have two birthstones to choose from: opal or tourmaline.

Opal, the primary October birthstone

The best known October birthstone is the opal. They’re amazingly diverse rocks, taking on different appearances depending on how they formed. Precious opals, known for their flashy iridescent colors, are popular in some jewelry. But even the less dazzling common opals possess a quiet beauty that makes them popular in specimen collections.

Unlike most other gemstones, opals don’t qualify as minerals in the usual sense. They contain myriads of tiny silica spheres in a tightly-packed lattice. These gemstones are famous for their play of colors. They flash rainbow hues when moved. The colors come from the interference of light with their internal structures.

Opals form in near-surface volcanic rocks, within cavities and cracks. In sedimentary volcanic ash rock, percolating water in the ground dissolves silica that eventually precipitates to form the opal. On rare occasions, it becomes the replacement material for fossils – shells, bones, wood – whose original material had dissolved away.

Characteristics of opals

An opal is a soft stone, easily altered in appearance by changes in heat and pressure. Varying amounts of water within it determine the appearance of the gemstone. When water evaporates out of an opal, the stone appears slightly smaller and the stress of the evaporation creates cracks on it.

Australia mines most of the world’s opals. That’s especially the case for magnificent black opals. Ethiopia is another emerging source of opals. At a smaller scale, a wide variety of opals are found in northern Nevada; some of those opals are in the form of fossilized wood. Other commercial sources of opal are Mexico, Canada, Brazil, Honduras, Nicaragua, Guatemala, Turkey and the Czech Republic.

Impurities within the stones create the characteristic colors of opals. Milky or pearly opals indicate tiny gas bubble inclusions. Yellows and reds indicate iron oxides inclusions. The spectacular black opals that sometimes flash green, blue and red get their color from magnesium oxides and organic carbon within the stone. Perhaps the most valuable opal pattern is the harlequin. It has large angular patches of red, yellow and green resembling the checks on a clown’s costume.

An oval polished opal showing roughly squarish colors of red, yellow, blue and green.
A Harlequin opal. Image via Aisha Brown/ Wikimedia Commons (CC BY-SA 2.0).

Opal lore

The name opal is derived from the Sanskrit word “upala,” as well as the Latin “opalus,” meaning “precious stone.”

The ancient Roman natural historian Pliny the Elder wrote about the captivating iridescence of the opal in his book, The Natural History of Precious Stones.

Of all precious stones, it is opal that presents the greatest difficulties of description, it displaying at once the piercing fire of carbunculus, the purple brilliancy of amethystos, and the sea-green of smaragdus, the whole blended together and refulgent with a brightness that is quite incredible.

There is an Indian legend about the origin of the opal. As Willard Heaps wrote in Gemstones:

… the gods Brahma, Vishnu and Shiva once vied in jealous love for a beautiful woman. This angered the Eternal, who changed the fair mortal into a creature made of mist. Thereupon each of the three gods endowed her with his own color so as to be able to recognize her. Brahma gave her the glorious blue of the heavens, Vishnu enriched her with the splendor of gold and Shiva lent her his flaming red. But all this was in vain, since the lovely phantom was whisked away by the winds. Finally, the Eternal took pity on her and transformed her into a stone, the opal, that sparkles in all the colors of the rainbow.

Heaps also wrote that ancient cultures attached meaning to opals. Romans called opals the Cupid stone. Asians called it the anchor of hope. Arabians believed they fell from the sky. In Poland, People thought that opals made their wearer invisible, hence the opal was the talisman of thieves and spies.

October birthstone: evil superstitions

During the medieval period, a change in color intensity of an opal was believed to indicate if its wearer was ill or in good health. Supposedly the opal maintained a strong heart, prevented fainting, protected against infection and cleansed foul-smelling air. The stone, as in ancient times, still represented a symbol of hope.

But the opal’s reputation changed in the mid-14th century. The Black Death swept across Europe, killing 1/4 of its population. People thought the gem was the cause of death. When worn by someone struck with the deadly plague, it would appear brilliant only until the person died. Then it would change in appearance, losing its luster. In reality, it was the sensitivity of this stone to changes in temperature that altered its appearance, as the heat from a burning fever gave way to the cold of death.

In Elizabethan England, people treasured the opal for its beauty. Shakespeare wrote of it in his play Twelfth Night as the queen of gems. Queen Victoria is said to have loved opals and presented them to her children, thus making the stone popular. But the stone continued to have a mixed reputation, chiefly due to a novel, Anne of Geierstein, written by Sir Walter Scott in 1829 that depicted it as a stone of evil.

In Australia, opals have long been a part of Australian Aboriginal cultures. In one story, set during the Dreamtime, a pelican was resting in an area of beautiful colors. When he pecked at the colored stones, a spark flew out and lit the dry grass on fire. As the fire spread, it reached his people who, for the first time, were able to cook fish and meat.

Tourmaline, an alternate October birthstone

An alternate October birthstone is tourmaline, a gemstone that exhibits the broadest spectrum of gemstone colors. Gem-quality forms of this mineral have in the past been misidentified as rubies, emeralds and sapphires. In fact, a famous tourmaline – the size of a pigeon’s egg – belonging to the Russian empress Catherine the Great, was long thought to be a ruby.

The name of this gemstone is believed to derive from the Singhalese (Sri Lankan) word toramalli, a term applied to colorful stones.

A squarish green linear crystal with an inclusion of some white crystals at the top.
A green elbaite crystal, a type of tourmaline, from Brazil. (The white crystal is the mineral albite.) Image via Ivar Leidus/ Wikimedia Commons (CC BY-SA 4.0).

Tourmaline characteristics

Tourmaline is a complex boron-bearing silicate mineral that can also contain other elements such as aluminum, magnesium, sodium, iron and lithium. They come in a myriad of colors: yellow, green, red, blue, pink, brown and black. Metals within the crystal structure are responsible for the gemstone colors. Pink, for example, comes from the presence of manganese. Iron produces black to deep brown colors, while magnesium creates browns and yellows. Tourmalines rich in lithium can produce several different colors such as blues, greens and reds. Some crystals even have bicolored properties. One variety, called the watermelon tourmaline, has green outer edges that transition to a transparent white zone that gives way to a pink or light red interior.

When tourmalines are warmed or rubbed, they attract small bits of paper, lint and ash. This occurs because the gem becomes charged with static electricity. In fact, Benjamin Franklin used this gem in his studies of electricity. Maintaining a tourmaline exhibit at museums requires frequent cleaning of the gemstone because heat from lights of the display case create a charge in the stone that attracts dust.

Compared with other gemstones, tourmalines are a relatively recent discovery. Hence, it lacks the rich lore that accompanies many other precious gems. However, some people think of tourmaline as the peace stone, believed to dispel fear and make its wearer calm.

Black rectangular tourmaline crystals on white rock, with a small green fluorite crystal.
Schorl is the most commonly found form of tourmaline. In this specimen from Namibia, a small piece of green fluorite is perched atop the tourmaline crystals. Image via Robert M. Lavinsky/ Wikimedia Commons (CC BY-SA 3.0).

Find out about birthstones for the rest of the year

January birthstone
February birthstone
March birthstone
April birthstone
May birthstone
June birthstone
July birthstone
August birthstone
September birthstone
October birthstone
November birthstone
December birthstone

Bottom line: October has two birthstones, opal and tourmaline.

The post October birthstone: Colorful opal and tourmaline first appeared on EarthSky.



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Wow! Another one! Big new sungrazer comet could get SUPER-bright

Sungrazer comet: White comet with long tail in a starry sky.
There’s a brand new comet in the sky! No, not Comet C/2023 A3 Tsuchinshan-ATLAS. Like the incredibly bright Comet Ikeya–Seki (above) in 1965, the new one is what’s called a sungrazer comet. How bright will it get? Image via NASA/ Wikimedia Commons.

Big new sungrazer comet

Heads up, comet-watchers! The ATLAS survey in Hawaii has discovered another new comet that could become bright in Earth’s skies. The discovery date is September 27, 2024. The comet is so new it’s still waiting for its name. But for now it has the designation of A11bP7I. Predictions for the comet have it reaching as bright as magnitude -5 to -7 when it comes closest to the sun, at perihelion, on October 28. Those ranges would make the comet even brighter than the brightest planet, Venus. It might even be visible in the daytime sky. But! Keep in mind that comets are notoriously unpredictable.

The Southern Hemisphere will have the best view before perihelion. After its close encounter with the sun (if it survives!) it could put on a fantastic show for the Northern Hemisphere in the morning skies. It would definitely be something to wake up early for.

In the meantime, don’t forget the other comet in Earth’s skies right now. C/2023 A3 Tsuchinshan-ATLAS will be visible in the morning sky in the east through October 2. Afterwards, it’ll reappear on the other side of the sun in the evening sky after about October 12.

A Kreutz sungrazer

The new sungrazing comet is part of the Kreutz sungrazers. These are comets that come perilously close to the sun, where they can disintegrate or, if we’re lucky, become fantastically bright. Many of the comets through history that have been given the name “Great” (for example the Great Comet of 1882, the Great Comet of 1106 and the Great Comet of 371 BC) were all Kreutz sungrazers. More recently, Comet Ikeya–Seki in 1965 was a Kreutz sungrazer that became as bright as magnitude -11. That’s as bright as a first quarter moon.

Scientists believe Kreutz sungrazers all come from a big comet that broke up a couple millennia ago. Most Kreutz sungrazers are small fragments, but this one may be larger than most.

Will it become as bright as Ikeya-Seki? Not likely. The new comet is about 1 astronomical unit (AU) from the sun now. And it’s about 4 to 5 magnitudes dimmer than Ikeya-Seki was at that distance. The comet is currently around magnitude 15.

But expectations for this comet are still high. Check back for updates, and keep an eye out in late October and early November for this comet! If you get great images, submit them to us!

Bottom line: A big new sungrazing comet could get really bright – and even be visible in daylight – in late October and early November.

Via Spaceweather

Via Starwalk

The post Wow! Another one! Big new sungrazer comet could get SUPER-bright first appeared on EarthSky.



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Sungrazer comet: White comet with long tail in a starry sky.
There’s a brand new comet in the sky! No, not Comet C/2023 A3 Tsuchinshan-ATLAS. Like the incredibly bright Comet Ikeya–Seki (above) in 1965, the new one is what’s called a sungrazer comet. How bright will it get? Image via NASA/ Wikimedia Commons.

Big new sungrazer comet

Heads up, comet-watchers! The ATLAS survey in Hawaii has discovered another new comet that could become bright in Earth’s skies. The discovery date is September 27, 2024. The comet is so new it’s still waiting for its name. But for now it has the designation of A11bP7I. Predictions for the comet have it reaching as bright as magnitude -5 to -7 when it comes closest to the sun, at perihelion, on October 28. Those ranges would make the comet even brighter than the brightest planet, Venus. It might even be visible in the daytime sky. But! Keep in mind that comets are notoriously unpredictable.

The Southern Hemisphere will have the best view before perihelion. After its close encounter with the sun (if it survives!) it could put on a fantastic show for the Northern Hemisphere in the morning skies. It would definitely be something to wake up early for.

In the meantime, don’t forget the other comet in Earth’s skies right now. C/2023 A3 Tsuchinshan-ATLAS will be visible in the morning sky in the east through October 2. Afterwards, it’ll reappear on the other side of the sun in the evening sky after about October 12.

A Kreutz sungrazer

The new sungrazing comet is part of the Kreutz sungrazers. These are comets that come perilously close to the sun, where they can disintegrate or, if we’re lucky, become fantastically bright. Many of the comets through history that have been given the name “Great” (for example the Great Comet of 1882, the Great Comet of 1106 and the Great Comet of 371 BC) were all Kreutz sungrazers. More recently, Comet Ikeya–Seki in 1965 was a Kreutz sungrazer that became as bright as magnitude -11. That’s as bright as a first quarter moon.

Scientists believe Kreutz sungrazers all come from a big comet that broke up a couple millennia ago. Most Kreutz sungrazers are small fragments, but this one may be larger than most.

Will it become as bright as Ikeya-Seki? Not likely. The new comet is about 1 astronomical unit (AU) from the sun now. And it’s about 4 to 5 magnitudes dimmer than Ikeya-Seki was at that distance. The comet is currently around magnitude 15.

But expectations for this comet are still high. Check back for updates, and keep an eye out in late October and early November for this comet! If you get great images, submit them to us!

Bottom line: A big new sungrazing comet could get really bright – and even be visible in daylight – in late October and early November.

Via Spaceweather

Via Starwalk

The post Wow! Another one! Big new sungrazer comet could get SUPER-bright first appeared on EarthSky.



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Lifeform of the week: Axolotls, the key to eternal youth?

Have you ever heard of the axolotl? This friendly animal is fascinating, and it stays in a young form its whole life, like Peter Pan. Axolotls are amphibians that never grow beyond their tadpole shapes. Furthermore, axolotls can regenerate almost all parts of their bodies, not just their limbs. It makes them a popular subject for medical research.

Where do axolotls live?

There are 33 species of axolotls, which are distributed in North America from southwest Alaska and southern Canada to the highlands of Mexico. In Mexico, there are 17 species in the northeast and center of the country, 16 of which are endemic. Sadly, most wild Mexican axolotls are critically endangered.

Their habitats are shallow-water lakes or canals with lots of aquatic vegetation. They are sometimes confused with salamanders. In fact, the two have a lot in common. The main difference is that salamanders are born in water as tadpoles but then undergo a metamorphosis and leave the water to inhabit land. Axolotls, however, are completely aquatic.

This environment is where they feed on worms, larvae, insect eggs, mollusks, crustaceans and some small fish. Axolotls catch food by opening their mouths quickly, sucking their food in like a vacuum, and then using their small teeth to retain the food in their mouths.

Axolotls: Green creature with brown dots and feathery gills behind its head. Walking on thin legs with four fingers.
Axolotls are sometimes confused with salamanders. But salamanders are born in water as tadpoles and then undergo a metamorphosis to inhabit land. Axolotls, however, are completely aquatic. Image via Seánín Óg/ iNaturalist (CC BY-NC-ND).

Axolotls have a unique anatomy

The axolotl is a peculiar amphibian. When the egg hatches underwater, the axolotl maintains its tadpole-like dorsal fin for life. A female lays between 300 and 1,000 eggs per clutch. The eggs are transparent and take between 10 and 14 days to hatch.

Axolotls are born without limbs but later develop four legs. First, they grow the two front legs. A week later, they develop the two back ones. They have four toes on their front paws and five on their back paws.

Another curious fact is axolotls don’t have eyelids, which makes them sensitive to light. Therefore, they must remain in dark environments. Not surprisingly, axolotls are nocturnal animals.

The average size of an axolotl is 6 inches (15 cm) in length, although there are some that measure up to 12 inches (30 cm). In addition, females are wider than males and have a shorter fin/tail.

Wide, flat purple creature with a finned tail, 4 legs, and external gills with filaments behind its head.
Axolotls maintain their tadpole-like dorsal fins for life. They are born without limbs but later develop 4 legs. Also, they don’t have eyelids. Image via Raphael Brasileiro/ Pexels.

Various ways to breathe

Axolotls have three different ways to breathe: through gills, lungs and their skin.

Those “feathers” on both sides of the head are their external gills. This is the primary means by which they breathe. When water enters through the mouth, it escapes through the gills. Through this process, the axolotl brings oxygen to its blood.

What we call breathing is – in the axolotl – technically known as gas exchange, something that is also done through the skin and lungs.

The quality of the water they live in is extremely important. The life expectancy of axolotls in captivity ranges from 10 to 15 years, while in the wild they only live three to six years.

Fleshy pink creature that looks like it is smiling. It has 2 small, black eyes and stubby external gills.
Axolotls can breathe through gills, lungs and their skin. Image via Mattias Banguese/ Unsplash.

An axolotl’s regeneration superpower

Axolotls have the incredible ability to regenerate from their tails/fins to important organs such as the heart, brain, lungs or kidneys. In fact, if they lose any of their limbs, they grow back.

When they regenerate an organ, it doesn’t even leave a scar! The organs look fresh and new. For this reason, axolotls are part of large scientific studies worldwide.

Black creature on a sandy sea floor. It has 4 thin legs with long toes.
These fascinating creatures can regenerate their tails/fins, hearts, brains, lungs and kidneys. Image via Nathan Guzman/ Unsplash.

The axolotl is a colorful animal

Axolotls can have a great variety of colors, although they mainly have four shades. The pink axolotl is the most famous. This one has a happy and tender face, and funny little round black eyes.

The gold one is similar but with a slight golden tone.

The albino axolotl is rather whitish, and its eyes are red. Albinism – or lack of skin color – is caused by a recessive gene transmitted to offspring when both parents carry the gene.

And last but not least are those that camouflage themselves best among aquatic plants, the green-brown or black axolotls.

A pink and a black creature with feathery external gills. The gills are darker than the rest of the body.
These amphibians are colorful. They can be pink, golden, white or black/dark green/brown. Image via TK/ Unsplash.

The axolotl is in critical danger of extinction

Unfortunately, wild axolotls are critically endangered due to several factors. One is the contamination of the waters where they live, largely due to chemical pollution, plastic waste and other garbage dumped in the water.

Luis Zambrano, professor of zoology at the National Autonomous University of Mexico, wrote:

All our aquatic animals suffer from poor water quality, but amphibians more so because they have to breathe with their skin.

Another important factor is axolotls are captured illegally and exploited for their medicinal uses (without a scientific basis), as food for humans and also sold as pets.

Another factor causing the decline of the axolotl population is the introduction of invasive species for human consumption. These species feed on axolotls, becoming their predators.

Currently, different environmental regulations protect axolotls. Plus, there are various research and conservation centers that work hard to change their situation.

However, the reintroduction into their natural habitat is not occurring yet because the threats are still high. According to experts, the natural environment must first be properly conditioned.

Pink creature with neck gills in an aquarium. It is reflected in the glass.
Axolotls are critically endangered due to pollution, illegal fishing, their use as food and for medicinal purposes, the introduction of invasive species and because they are sold as pets. Image via Guillaume de Germain/ Unsplash.

Axolotls in mythology

Axolotls have inhabited Mexico’s great lakes area since pre-Hispanic times, when the Aztecs lived. They are part of the culture and mythology of the Mexican people. In fact, their name comes from Nahuatl. Atl means water and xolotl means monster. Put together, it means water monster.

These small animals are protagonists of Mexican mythology, since the axolotl is related to the Aztec god Xolotl, who disguised himself as this animal to avoid being sacrificed.

Axolotls: A couple of fishy white aquatic creatures with feathery external gills, hidden among rocks and plants.
Axolotls have been part of the culture and mythology of the Mexican people since the days of the Aztecs. Image via Guillaume de Germain/ Unsplash.

Bottom line: This spectacular amphibian keeps its body forever young. It never loses its tadpole tail and can regenerate not only its limbs or fin/tail, but also its organs!

The adorable leaf sheep sea slug: Lifeform of the week.

Incredible sea rays: Lifeform of the week

The post Lifeform of the week: Axolotls, the key to eternal youth? first appeared on EarthSky.



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Have you ever heard of the axolotl? This friendly animal is fascinating, and it stays in a young form its whole life, like Peter Pan. Axolotls are amphibians that never grow beyond their tadpole shapes. Furthermore, axolotls can regenerate almost all parts of their bodies, not just their limbs. It makes them a popular subject for medical research.

Where do axolotls live?

There are 33 species of axolotls, which are distributed in North America from southwest Alaska and southern Canada to the highlands of Mexico. In Mexico, there are 17 species in the northeast and center of the country, 16 of which are endemic. Sadly, most wild Mexican axolotls are critically endangered.

Their habitats are shallow-water lakes or canals with lots of aquatic vegetation. They are sometimes confused with salamanders. In fact, the two have a lot in common. The main difference is that salamanders are born in water as tadpoles but then undergo a metamorphosis and leave the water to inhabit land. Axolotls, however, are completely aquatic.

This environment is where they feed on worms, larvae, insect eggs, mollusks, crustaceans and some small fish. Axolotls catch food by opening their mouths quickly, sucking their food in like a vacuum, and then using their small teeth to retain the food in their mouths.

Axolotls: Green creature with brown dots and feathery gills behind its head. Walking on thin legs with four fingers.
Axolotls are sometimes confused with salamanders. But salamanders are born in water as tadpoles and then undergo a metamorphosis to inhabit land. Axolotls, however, are completely aquatic. Image via Seánín Óg/ iNaturalist (CC BY-NC-ND).

Axolotls have a unique anatomy

The axolotl is a peculiar amphibian. When the egg hatches underwater, the axolotl maintains its tadpole-like dorsal fin for life. A female lays between 300 and 1,000 eggs per clutch. The eggs are transparent and take between 10 and 14 days to hatch.

Axolotls are born without limbs but later develop four legs. First, they grow the two front legs. A week later, they develop the two back ones. They have four toes on their front paws and five on their back paws.

Another curious fact is axolotls don’t have eyelids, which makes them sensitive to light. Therefore, they must remain in dark environments. Not surprisingly, axolotls are nocturnal animals.

The average size of an axolotl is 6 inches (15 cm) in length, although there are some that measure up to 12 inches (30 cm). In addition, females are wider than males and have a shorter fin/tail.

Wide, flat purple creature with a finned tail, 4 legs, and external gills with filaments behind its head.
Axolotls maintain their tadpole-like dorsal fins for life. They are born without limbs but later develop 4 legs. Also, they don’t have eyelids. Image via Raphael Brasileiro/ Pexels.

Various ways to breathe

Axolotls have three different ways to breathe: through gills, lungs and their skin.

Those “feathers” on both sides of the head are their external gills. This is the primary means by which they breathe. When water enters through the mouth, it escapes through the gills. Through this process, the axolotl brings oxygen to its blood.

What we call breathing is – in the axolotl – technically known as gas exchange, something that is also done through the skin and lungs.

The quality of the water they live in is extremely important. The life expectancy of axolotls in captivity ranges from 10 to 15 years, while in the wild they only live three to six years.

Fleshy pink creature that looks like it is smiling. It has 2 small, black eyes and stubby external gills.
Axolotls can breathe through gills, lungs and their skin. Image via Mattias Banguese/ Unsplash.

An axolotl’s regeneration superpower

Axolotls have the incredible ability to regenerate from their tails/fins to important organs such as the heart, brain, lungs or kidneys. In fact, if they lose any of their limbs, they grow back.

When they regenerate an organ, it doesn’t even leave a scar! The organs look fresh and new. For this reason, axolotls are part of large scientific studies worldwide.

Black creature on a sandy sea floor. It has 4 thin legs with long toes.
These fascinating creatures can regenerate their tails/fins, hearts, brains, lungs and kidneys. Image via Nathan Guzman/ Unsplash.

The axolotl is a colorful animal

Axolotls can have a great variety of colors, although they mainly have four shades. The pink axolotl is the most famous. This one has a happy and tender face, and funny little round black eyes.

The gold one is similar but with a slight golden tone.

The albino axolotl is rather whitish, and its eyes are red. Albinism – or lack of skin color – is caused by a recessive gene transmitted to offspring when both parents carry the gene.

And last but not least are those that camouflage themselves best among aquatic plants, the green-brown or black axolotls.

A pink and a black creature with feathery external gills. The gills are darker than the rest of the body.
These amphibians are colorful. They can be pink, golden, white or black/dark green/brown. Image via TK/ Unsplash.

The axolotl is in critical danger of extinction

Unfortunately, wild axolotls are critically endangered due to several factors. One is the contamination of the waters where they live, largely due to chemical pollution, plastic waste and other garbage dumped in the water.

Luis Zambrano, professor of zoology at the National Autonomous University of Mexico, wrote:

All our aquatic animals suffer from poor water quality, but amphibians more so because they have to breathe with their skin.

Another important factor is axolotls are captured illegally and exploited for their medicinal uses (without a scientific basis), as food for humans and also sold as pets.

Another factor causing the decline of the axolotl population is the introduction of invasive species for human consumption. These species feed on axolotls, becoming their predators.

Currently, different environmental regulations protect axolotls. Plus, there are various research and conservation centers that work hard to change their situation.

However, the reintroduction into their natural habitat is not occurring yet because the threats are still high. According to experts, the natural environment must first be properly conditioned.

Pink creature with neck gills in an aquarium. It is reflected in the glass.
Axolotls are critically endangered due to pollution, illegal fishing, their use as food and for medicinal purposes, the introduction of invasive species and because they are sold as pets. Image via Guillaume de Germain/ Unsplash.

Axolotls in mythology

Axolotls have inhabited Mexico’s great lakes area since pre-Hispanic times, when the Aztecs lived. They are part of the culture and mythology of the Mexican people. In fact, their name comes from Nahuatl. Atl means water and xolotl means monster. Put together, it means water monster.

These small animals are protagonists of Mexican mythology, since the axolotl is related to the Aztec god Xolotl, who disguised himself as this animal to avoid being sacrificed.

Axolotls: A couple of fishy white aquatic creatures with feathery external gills, hidden among rocks and plants.
Axolotls have been part of the culture and mythology of the Mexican people since the days of the Aztecs. Image via Guillaume de Germain/ Unsplash.

Bottom line: This spectacular amphibian keeps its body forever young. It never loses its tadpole tail and can regenerate not only its limbs or fin/tail, but also its organs!

The adorable leaf sheep sea slug: Lifeform of the week.

Incredible sea rays: Lifeform of the week

The post Lifeform of the week: Axolotls, the key to eternal youth? first appeared on EarthSky.



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Fomalhaut is the loneliest star in the southern sky

Green ecliptic line with white dots for Saturn and Fomalhaut.
On October evenings in 2024, Saturn can guide you to the lonely, but bright, star Fomalhaut. They are the brightest object in that area of the sky. Chart via EarthSky.

Fomalhaut, bright and lonely

Fomalhaut, aka Alpha Piscis Austrinus, is also called the Loneliest Star. It’s because Fomalhaut is the only bright star in a wide stretch of sky. From the Northern Hemisphere, Fomalhaut arcs in solitary splendor across the southern sky in autumn. Therefore, some call it the Autumn Star. From the Southern Hemisphere, you’ll look higher up to see Fomalhaut in your season of spring. In 2024, Fomalhaut isn’t so solitary, though! A bright planet, Saturn, appears near it in the sky. Of course, Fomalhaut will be the one that’s twinkling since Saturn will shine with a steady light.

Keep reading to learn more about this young star. It’s of special interest to astronomers because it has a debris ring around it. Astronomers think new worlds might be forming in Fomalhaut’s ring, as an early stage in the planet-forming process.

Very bright bluish star with many more stars in background.
The star Fomalhaut as seen by an Earth-based telescope on November 13, 2008. Image via NASA/ ESA/ Digitized Sky Survey 2/ Davide De Martin (ESA/Hubble)/ ESA.

How to see it

Fomalhaut is the 18th brightest star in the night sky. It’s part of the faint constellation Piscis Austrinus the Southern Fish. In a dark sky, you’ll see a half-circle of faint stars of which bright Fomalhaut is a part. This star pattern marks the open mouth of the Southern Fish.

In early September, Fomalhaut is opposite the sun. So, it shines in the sky all night. It reaches its culmination – its highest point in the sky – around local midnight in mid-September.

Fomalhaut culminates at different times on different dates. Here are just a few approximate times and dates of culmination:

July 15: 4:30 a.m. daylight saving time (DST)
August 15: 2:30 a.m. DST
September 15: 12:30 a.m. DST
October 15: 10:30 p.m. DST
November 15: 8:30 p.m. DST
December 15: 5:30 p.m. standard time

Finder chart for the moon, Saturn and Fomalhaut

Saturn in October near the star Fomalhaut with the moon on October 13 and 14 near Saturn.
The bright waxing gibbous moon will hang near Saturn and the bright star Fomalhaut in the east after sunset on the evenings of October 13 and 14, 2024. They’ll set a few hours before dawn.

The view from different hemispheres

From the Northern Hemisphere, you can see Fomalhaut from as far north as 60 degrees latitude (southern Alaska, central Canada, northern Europe), where it just skims the southern horizon. From the Southern Hemisphere, Fomalhaut appears much higher in the sky. You can use one of several stargazing smartphone apps, some that are free, to help you find it. Or visit Stellarium-Web.org, the free online planetarium, and enter your location and time.

Star chart with arrow showing pointing from the west side of the Great Square of Pegasus to Fomalhaut.
A view of the sky from Austin, Texas, about an hour after sunset on October 1. To find Fomalhaut (and Saturn) locate the great square of Pegasus. Then use the west side of the square to guide you south, and about three times its length, you’ll find Fomalhaut. In 2024, the steady light of Saturn will lie between the Great Square and Fomalhaut. Image via Stellarium.

Rings of dust and gas

Fomalhaut is a hot white star about 25 light-years away. It’s almost twice the mass and size of our sun but radiates over 16 times the sun’s energy. Fomalhaut has a companion star less than a light-year away from it. The companion is an orange dwarf star, about 70% the mass of our sun. A third member of the Fomalhaut star system was announced in 2013, a small reddish star about 2.5 light-years from Fomalhaut. From Earth, we see the third star located in the constellation Aquarius instead of Piscis Austrinus.

Fomalhaut itself is a young star, just 440 million years old. That’s in contrast to 4 1/2 billion years for our sun. Fomalhaut is of special interest to astronomers because it has several rings of dust and gas around it, early indications of planets in the process of formation around this star. Astronomers have detected inner debris disks close to the star, within a few astronomical units (AU) from the star.

There’s a much larger, thicker debris ring about 133 AU from the star. A study published in 2008 generated a lot of excitement when Hubble Space Telescope images, taken in 2004, 2006 and 2008 showed an apparent planet very close to this debris ring. Astronomers first thought it was the first directly imaged exoplanet. But data from other telescopes brought that conclusion under scrutiny. And, by 2014, this object was no longer visible to Hubble.

A possible explanation

So what happened? Astronomers think that the “planet” was actually a large dust cloud generated by the collision of two large bodies near the ring. And over time, that dust cloud may have dissipated. And even though it turned out not to be a planet, astronomers were pleased. Catching the aftermath of a collision in a planet-forming disk was good, too! The event provided clues to a deeper understanding about how planets form.

Left: a dark circle with a fuzzy red ring around it. Right: a series of dots, fading from bright to dim.
On the left, a Hubble Space Telescope image showing Fomalhaut’s debris disk. The star itself has been blocked so its brightness doesn’t drown out the view of the faint ring. The small box shows the object once thought to be a planet (but no more). On the right is a simulation, based on observations, of how the object appeared from 2004 to 2014. The object is now thought to be the result of a collision in the disk. Image via NASA.

Fomalhaut in history and mythology

The name Fomalhaut derives from the Arabic Fum al Hut, meaning Mouth of the Fish.

In the sky visible from the Northern Hemisphere, the constellation Aquarius the Water Bearer resides above Fomalhaut’s constellation Piscis Austrinus. You can see a zigzag line of stars from Aquarius to Piscis Austrinus. In sky lore, this line of stars represents water from the Jar of the Water Bearer, trickling into the open Mouth of the Fish.

According to Richard Hinckley Allen, Fomalhaut was one of the four guardians of the heavens to the ancient Persians, in 3,000 BCE, called by them Hastorang. (The other guardians were Aldebaran in Taurus, Antares in Scorpius, and Regulus in Leo.) Around 2,500 BCE, Fomalhaut helped mark the location of the winter solstice, meaning that it helped to define the location in the sky where the sun crossed the meridian at noon on the first day of winter. Also Allen also says that in 500 BCE, people worshipped Fomalhaut at the temple of Demeter in Eleusis, in ancient Greece.

Antique etching of an old man carrying a water jug. Below him is a fish. Stars are scattered over the chart.
View larger. | Aquarius the Water Carrier appears above Piscis Austrinus the Southern Fish, in the Celestial Atlas by Alexander Jamieson, published in 1822. In the illustration, water from the Water Jar of Aquarius is going into the Mouth of the Southern Fish. if it’s dark where you are, you can easily see a zigzag line of stars representing this flow of water. Image via Wikimedia (public domain).

Bottom line: Fomalhaut is relatively easy to spot as it shines brightly in an area of sky with no other bright sources nearby, except for planet Saturn in 2024. It’s of special interest to astronomers because of debris rings around it that are possibly the beginnings of a planetary system.

Read more: Fomalhaut has 3 nested belts around the star

The post Fomalhaut is the loneliest star in the southern sky first appeared on EarthSky.



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Green ecliptic line with white dots for Saturn and Fomalhaut.
On October evenings in 2024, Saturn can guide you to the lonely, but bright, star Fomalhaut. They are the brightest object in that area of the sky. Chart via EarthSky.

Fomalhaut, bright and lonely

Fomalhaut, aka Alpha Piscis Austrinus, is also called the Loneliest Star. It’s because Fomalhaut is the only bright star in a wide stretch of sky. From the Northern Hemisphere, Fomalhaut arcs in solitary splendor across the southern sky in autumn. Therefore, some call it the Autumn Star. From the Southern Hemisphere, you’ll look higher up to see Fomalhaut in your season of spring. In 2024, Fomalhaut isn’t so solitary, though! A bright planet, Saturn, appears near it in the sky. Of course, Fomalhaut will be the one that’s twinkling since Saturn will shine with a steady light.

Keep reading to learn more about this young star. It’s of special interest to astronomers because it has a debris ring around it. Astronomers think new worlds might be forming in Fomalhaut’s ring, as an early stage in the planet-forming process.

Very bright bluish star with many more stars in background.
The star Fomalhaut as seen by an Earth-based telescope on November 13, 2008. Image via NASA/ ESA/ Digitized Sky Survey 2/ Davide De Martin (ESA/Hubble)/ ESA.

How to see it

Fomalhaut is the 18th brightest star in the night sky. It’s part of the faint constellation Piscis Austrinus the Southern Fish. In a dark sky, you’ll see a half-circle of faint stars of which bright Fomalhaut is a part. This star pattern marks the open mouth of the Southern Fish.

In early September, Fomalhaut is opposite the sun. So, it shines in the sky all night. It reaches its culmination – its highest point in the sky – around local midnight in mid-September.

Fomalhaut culminates at different times on different dates. Here are just a few approximate times and dates of culmination:

July 15: 4:30 a.m. daylight saving time (DST)
August 15: 2:30 a.m. DST
September 15: 12:30 a.m. DST
October 15: 10:30 p.m. DST
November 15: 8:30 p.m. DST
December 15: 5:30 p.m. standard time

Finder chart for the moon, Saturn and Fomalhaut

Saturn in October near the star Fomalhaut with the moon on October 13 and 14 near Saturn.
The bright waxing gibbous moon will hang near Saturn and the bright star Fomalhaut in the east after sunset on the evenings of October 13 and 14, 2024. They’ll set a few hours before dawn.

The view from different hemispheres

From the Northern Hemisphere, you can see Fomalhaut from as far north as 60 degrees latitude (southern Alaska, central Canada, northern Europe), where it just skims the southern horizon. From the Southern Hemisphere, Fomalhaut appears much higher in the sky. You can use one of several stargazing smartphone apps, some that are free, to help you find it. Or visit Stellarium-Web.org, the free online planetarium, and enter your location and time.

Star chart with arrow showing pointing from the west side of the Great Square of Pegasus to Fomalhaut.
A view of the sky from Austin, Texas, about an hour after sunset on October 1. To find Fomalhaut (and Saturn) locate the great square of Pegasus. Then use the west side of the square to guide you south, and about three times its length, you’ll find Fomalhaut. In 2024, the steady light of Saturn will lie between the Great Square and Fomalhaut. Image via Stellarium.

Rings of dust and gas

Fomalhaut is a hot white star about 25 light-years away. It’s almost twice the mass and size of our sun but radiates over 16 times the sun’s energy. Fomalhaut has a companion star less than a light-year away from it. The companion is an orange dwarf star, about 70% the mass of our sun. A third member of the Fomalhaut star system was announced in 2013, a small reddish star about 2.5 light-years from Fomalhaut. From Earth, we see the third star located in the constellation Aquarius instead of Piscis Austrinus.

Fomalhaut itself is a young star, just 440 million years old. That’s in contrast to 4 1/2 billion years for our sun. Fomalhaut is of special interest to astronomers because it has several rings of dust and gas around it, early indications of planets in the process of formation around this star. Astronomers have detected inner debris disks close to the star, within a few astronomical units (AU) from the star.

There’s a much larger, thicker debris ring about 133 AU from the star. A study published in 2008 generated a lot of excitement when Hubble Space Telescope images, taken in 2004, 2006 and 2008 showed an apparent planet very close to this debris ring. Astronomers first thought it was the first directly imaged exoplanet. But data from other telescopes brought that conclusion under scrutiny. And, by 2014, this object was no longer visible to Hubble.

A possible explanation

So what happened? Astronomers think that the “planet” was actually a large dust cloud generated by the collision of two large bodies near the ring. And over time, that dust cloud may have dissipated. And even though it turned out not to be a planet, astronomers were pleased. Catching the aftermath of a collision in a planet-forming disk was good, too! The event provided clues to a deeper understanding about how planets form.

Left: a dark circle with a fuzzy red ring around it. Right: a series of dots, fading from bright to dim.
On the left, a Hubble Space Telescope image showing Fomalhaut’s debris disk. The star itself has been blocked so its brightness doesn’t drown out the view of the faint ring. The small box shows the object once thought to be a planet (but no more). On the right is a simulation, based on observations, of how the object appeared from 2004 to 2014. The object is now thought to be the result of a collision in the disk. Image via NASA.

Fomalhaut in history and mythology

The name Fomalhaut derives from the Arabic Fum al Hut, meaning Mouth of the Fish.

In the sky visible from the Northern Hemisphere, the constellation Aquarius the Water Bearer resides above Fomalhaut’s constellation Piscis Austrinus. You can see a zigzag line of stars from Aquarius to Piscis Austrinus. In sky lore, this line of stars represents water from the Jar of the Water Bearer, trickling into the open Mouth of the Fish.

According to Richard Hinckley Allen, Fomalhaut was one of the four guardians of the heavens to the ancient Persians, in 3,000 BCE, called by them Hastorang. (The other guardians were Aldebaran in Taurus, Antares in Scorpius, and Regulus in Leo.) Around 2,500 BCE, Fomalhaut helped mark the location of the winter solstice, meaning that it helped to define the location in the sky where the sun crossed the meridian at noon on the first day of winter. Also Allen also says that in 500 BCE, people worshipped Fomalhaut at the temple of Demeter in Eleusis, in ancient Greece.

Antique etching of an old man carrying a water jug. Below him is a fish. Stars are scattered over the chart.
View larger. | Aquarius the Water Carrier appears above Piscis Austrinus the Southern Fish, in the Celestial Atlas by Alexander Jamieson, published in 1822. In the illustration, water from the Water Jar of Aquarius is going into the Mouth of the Southern Fish. if it’s dark where you are, you can easily see a zigzag line of stars representing this flow of water. Image via Wikimedia (public domain).

Bottom line: Fomalhaut is relatively easy to spot as it shines brightly in an area of sky with no other bright sources nearby, except for planet Saturn in 2024. It’s of special interest to astronomers because of debris rings around it that are possibly the beginnings of a planetary system.

Read more: Fomalhaut has 3 nested belts around the star

The post Fomalhaut is the loneliest star in the southern sky first appeared on EarthSky.



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