Betelgeuse is ‘fainting’ but (probably) not about to explode

Big red blobby star image.

Betelgeuse imaged in ultraviolet light by the Hubble Space Telescope, and subsequently enhanced by NASA. The bright white spot is likely one of this star’s poles. Image via Andrea Dupree/ Ronald Gilliland/ NASA/ ESA/ Britannica.com.

The red supergiant star Betelgeuse – in the shoulder of the constellation Orion the Hunter – is one of the easiest-to-recognize stars in the night sky. It’s also one of the biggest stars we know, with a radius extending out to the distance of Mars’ from our sun, and possibly Jupiter! Plus, it’s famous for its name, featured in the movie Beetlejuice. And, as if those things weren’t enough, this star is also famous for the fact that it’ll someday explode and appear in our sky as a supernova, becoming visible in daytime and possibly outshining the moon at night.

In recent weeks, though, the chatter about Betelgeuse has been centered on something else entirely. Astronomers are excited about the fact that – since about October – this bright star has become noticeably dimmer. In the terminology of astronomers, the star is fainting.

What’s happening? Could it be a sign that Betelgeuse is about to explode as a supernova? Astronomers say probably not. Let’s consider the facts.

EarthSky 2020 lunar calendars are available! They make great gifts. Order now. Going fast!

Big red blobby star image, with orbits of solar system planets overlaid.

This image, made with the Atacama Large Millimeter/submillimeter Array (ALMA), shows the red supergiant Betelgeuse — one of the largest stars known. In the millimeter continuum the star is around 1,400 times larger than our sun. The overlaid annotation shows how large the star is compared to our solar system. Betelgeuse would engulf all 4 terrestrial planets — Mercury, Venus, Earth and Mars — and even the gas giant Jupiter. Only Saturn and more distant planets would be beyond its surface. Image via ESO.

Star chart of constellation Orion with outline and stars labeled.

Betelgeuse is normally one of 2 very bright stars in the constellation Orion the Hunter. The other bright star is Rigel. Notice Betelgeuse and Rigel on either side of the short, straight row of three medium-bright stars. That row of stars represents Orion’s Belt. You can easily find this pattern in the sky – these 3 stars in a short-straight row – if you look. Look approximately along the path that the sun travels during the day.

Betelgeuse is a well-known variable star, whose brightness ups and downs have been tracked for years by amateur and professional astronomers working with the American Association of Variable Star Observers (AAVSO). That’s why we know that there are multiple cycles for Betelgeuse’s rising and falling brightness. It’s conceivable that – when the minima of all the cycles come together – the star could look exceptionally faint, as it does now.

But the fact remains Betelgeuse is now dimmer than it has been in the past.

And that’s what’s caused some speculation that Betelgeuse could be about to go supernova. Astronomers, meanwhile, are urging caution on that idea. They say it’s unlikely Betelgeuse will explode anytime in the next 100,000 years … and maybe not until a million years from now.

What are some other possibilities for Betelgeuse’s strange and dramatic dip in brightness in late 2019? Astronomers have also suggested that the change in brightness could be due to some sort of eruption of gas or dust, or changes in the star’s surface brightness.

What would happen if Betelgeuse were to explode? This star is “nearby” in relative terms, but it’s still some 430 light-years from Earth. Note also that distance determinations are tricky, especially for red supergiant stars that vary in brightness unpredictably, as Betelgeuse does. Distance estimates vary and are often revised, with some as high as 650 light-years for Betelgeuse.

No matter what its precise distance, Betelgeuse isn’t among our closest star neighbors. Yet it’s normally one of the brightest stars in Earth’s sky. The reason is that Betelgeuse is a supergiant star. It is intrinsically very brilliant.

Such brilliance comes at a price, however. Betelgeuse’s enormous energy requires that its fuel be expended quickly (relatively speaking), and in fact Betelgeuse is now near the end of its lifetime. Someday soon (astronomically speaking), it will run out of fuel, collapse under its own weight, and then rebound in a spectacular supernova explosion.

When this happens, Betelgeuse will brighten enormously for a few weeks or months, perhaps to be as bright as the full moon and visible in broad daylight.

When will it happen? Probably not in our lifetimes.

Bottom line: The bright red star Betelgeuse in the constellation Orion the Hunter has become noticeably fainter in recent months. Does that means it’s about to explode? Probably not, astronomers say.

Read more: Will the star Betelgeuse explode someday?



from EarthSky https://ift.tt/2EImAYT
Big red blobby star image.

Betelgeuse imaged in ultraviolet light by the Hubble Space Telescope, and subsequently enhanced by NASA. The bright white spot is likely one of this star’s poles. Image via Andrea Dupree/ Ronald Gilliland/ NASA/ ESA/ Britannica.com.

The red supergiant star Betelgeuse – in the shoulder of the constellation Orion the Hunter – is one of the easiest-to-recognize stars in the night sky. It’s also one of the biggest stars we know, with a radius extending out to the distance of Mars’ from our sun, and possibly Jupiter! Plus, it’s famous for its name, featured in the movie Beetlejuice. And, as if those things weren’t enough, this star is also famous for the fact that it’ll someday explode and appear in our sky as a supernova, becoming visible in daytime and possibly outshining the moon at night.

In recent weeks, though, the chatter about Betelgeuse has been centered on something else entirely. Astronomers are excited about the fact that – since about October – this bright star has become noticeably dimmer. In the terminology of astronomers, the star is fainting.

What’s happening? Could it be a sign that Betelgeuse is about to explode as a supernova? Astronomers say probably not. Let’s consider the facts.

EarthSky 2020 lunar calendars are available! They make great gifts. Order now. Going fast!

Big red blobby star image, with orbits of solar system planets overlaid.

This image, made with the Atacama Large Millimeter/submillimeter Array (ALMA), shows the red supergiant Betelgeuse — one of the largest stars known. In the millimeter continuum the star is around 1,400 times larger than our sun. The overlaid annotation shows how large the star is compared to our solar system. Betelgeuse would engulf all 4 terrestrial planets — Mercury, Venus, Earth and Mars — and even the gas giant Jupiter. Only Saturn and more distant planets would be beyond its surface. Image via ESO.

Star chart of constellation Orion with outline and stars labeled.

Betelgeuse is normally one of 2 very bright stars in the constellation Orion the Hunter. The other bright star is Rigel. Notice Betelgeuse and Rigel on either side of the short, straight row of three medium-bright stars. That row of stars represents Orion’s Belt. You can easily find this pattern in the sky – these 3 stars in a short-straight row – if you look. Look approximately along the path that the sun travels during the day.

Betelgeuse is a well-known variable star, whose brightness ups and downs have been tracked for years by amateur and professional astronomers working with the American Association of Variable Star Observers (AAVSO). That’s why we know that there are multiple cycles for Betelgeuse’s rising and falling brightness. It’s conceivable that – when the minima of all the cycles come together – the star could look exceptionally faint, as it does now.

But the fact remains Betelgeuse is now dimmer than it has been in the past.

And that’s what’s caused some speculation that Betelgeuse could be about to go supernova. Astronomers, meanwhile, are urging caution on that idea. They say it’s unlikely Betelgeuse will explode anytime in the next 100,000 years … and maybe not until a million years from now.

What are some other possibilities for Betelgeuse’s strange and dramatic dip in brightness in late 2019? Astronomers have also suggested that the change in brightness could be due to some sort of eruption of gas or dust, or changes in the star’s surface brightness.

What would happen if Betelgeuse were to explode? This star is “nearby” in relative terms, but it’s still some 430 light-years from Earth. Note also that distance determinations are tricky, especially for red supergiant stars that vary in brightness unpredictably, as Betelgeuse does. Distance estimates vary and are often revised, with some as high as 650 light-years for Betelgeuse.

No matter what its precise distance, Betelgeuse isn’t among our closest star neighbors. Yet it’s normally one of the brightest stars in Earth’s sky. The reason is that Betelgeuse is a supergiant star. It is intrinsically very brilliant.

Such brilliance comes at a price, however. Betelgeuse’s enormous energy requires that its fuel be expended quickly (relatively speaking), and in fact Betelgeuse is now near the end of its lifetime. Someday soon (astronomically speaking), it will run out of fuel, collapse under its own weight, and then rebound in a spectacular supernova explosion.

When this happens, Betelgeuse will brighten enormously for a few weeks or months, perhaps to be as bright as the full moon and visible in broad daylight.

When will it happen? Probably not in our lifetimes.

Bottom line: The bright red star Betelgeuse in the constellation Orion the Hunter has become noticeably fainter in recent months. Does that means it’s about to explode? Probably not, astronomers say.

Read more: Will the star Betelgeuse explode someday?



from EarthSky https://ift.tt/2EImAYT
Aucun commentaire:
Libellés :

Astronomers find ‘missing’ neutron star after 32 years

Multicolored blob with white spot in middle.

The location of the recently discovered neutron star at the core of the Supernova 1987A remnant. Image via Cardiff University.

A team of astronomers at the University of Cardiff, Wales, believe they have discovered the “missing” neutron star at the center of Supernova 1987A (SN1987A), whose detonation was first seen in earthly skies in February 1987. The explosion occurred in the Large Magellanic Cloud, a companion dwarf galaxy to our home galaxy, the Milky Way. The astronomers said they found this supernova’s neutron star using the ALMA telescope in Chile.

The neutron star finally seems to be emerging from a thick cloud of dust which has completely obscured it for the last 32 years.

The discovery was reported in the Astrophysical Journal on November 19. The team – led by astronomer Phil Cigan of Cardiff University – found a particularly bright patch of dust exactly where the neutron star was predicted to be. Cigan commented in a statement:

For the very first time we can tell that there is a neutron star inside this cloud within the supernova remnant. Its light has been veiled by a very thick cloud of dust, blocking the direct light from the neutron star at many wavelengths like fog masking a spotlight.

Astronomer Mikako Matsuura, also of Cardiff University, specializes in the study of dust and molecules in supernova remnants and is a co-author of this latest study. She commented:

Although the light from the neutron star is absorbed by the dust cloud that surrounds it, this in turn makes the cloud shine in sub-millimeter light, which we can now see with the extremely sensitive ALMA telescope. Our new findings will now enable astronomers to better understand how massive stars end their lives, leaving behind these extremely dense neutron stars.

Supernova 1987A was the brightest and closest supernova since Kepler’s supernova of 1604. It detonated on the edge of the Tarantula Nebula in the Large Magellanic Cloud. Since the supernova is some 168,000 light-years distant, the explosion actually occurred that long ago. Ian Shelton and Oscar Duhalde at the Las Campanas Observatory in Chile – and Albert Jones in New Zealand – were the first to spot the supernova in Earth’s skies in 1987.

A blue supergiant star called Sanduleak A had exploded, about which little was known. Astronomers were optimistic that by studying the event they could see if their theories about the death of massive stars were correct. The hope was that the supernova would leave behind a neutron star: better still, an easily detectable pulsar (all pulsars are neutron stars, but not all neutron stars are pulsars). If so, then the chain of events from core-collapse supernova explosion to neutron star could at last be verified. It was seen as something of a golden opportunity to confirm what we thought we knew about Type II supernovae and their aftermath.

But, as the initial glow subsided and astronomers in the Southern Hemisphere watched and waited, there were no radio bursts from a pulsar, no X-ray glow: there was nothing at all. It was soon realized that if there were any sort of star left behind at the center of the supernova remnant, it was behind huge quantities of dust, completely hidden from our view. Astronomers realized with disappointment, and the sense of something intensely valuable slipping from their grasp, that the dust would take a very long time to clear enough to reveal what it was masking. But there were also those who wondered, as the original mass of Sanduleak A was not known, if the reason there was no visible trace of any remnant was simply because what lurked in the dark, behind the wall of dust, was a new black hole.

And there was something quite unexpected about SN1987A, which was not realized until afterwards: about three hours before the explosion was seen in Chile, Japanese neutrino observatories had, between them, detected 25 neutrinos from the event. This was seen as confirmation that the bulk of neutrinos from supernovae are emitted some time before the star detonates. This pre-supernova detection of neutrinos can perhaps lay claim to be the first true multi-messenger astronomical event.

Apart from a brief flurry of excitement a few years after the supernova, as a group of radio astronomers thought they had detected brief pulsar emissions, nothing at the centre of the supernova remnant has been observed. The tentative pulsar signals were not confirmed nor repeated.

But now, at long last, astronomers have verification of their Type II supernova theories. The discovery demonstrates that astronomy is often a long and frustrating waiting game, where events play out over years and decades.

EarthSky 2020 lunar calendars are available! They make great gifts. Order now. Going fast!

Ring of green spots inside purple halo, with orange patch inside brightening toward the center.

Composite image of Supernova 1987A, via NASA/ ESA/ NRAO.

Bottom line: Astronomers using the ALMA radio telescope in Chile said in late 2019 that they’ve found the small, compact neutron star created in Supernova 1987A.

Source: High Angular Resolution ALMA Images of Dust and Molecules in the SN 1987A Ejecta

Via Cardiff University



from EarthSky https://ift.tt/2scXOxj
Multicolored blob with white spot in middle.

The location of the recently discovered neutron star at the core of the Supernova 1987A remnant. Image via Cardiff University.

A team of astronomers at the University of Cardiff, Wales, believe they have discovered the “missing” neutron star at the center of Supernova 1987A (SN1987A), whose detonation was first seen in earthly skies in February 1987. The explosion occurred in the Large Magellanic Cloud, a companion dwarf galaxy to our home galaxy, the Milky Way. The astronomers said they found this supernova’s neutron star using the ALMA telescope in Chile.

The neutron star finally seems to be emerging from a thick cloud of dust which has completely obscured it for the last 32 years.

The discovery was reported in the Astrophysical Journal on November 19. The team – led by astronomer Phil Cigan of Cardiff University – found a particularly bright patch of dust exactly where the neutron star was predicted to be. Cigan commented in a statement:

For the very first time we can tell that there is a neutron star inside this cloud within the supernova remnant. Its light has been veiled by a very thick cloud of dust, blocking the direct light from the neutron star at many wavelengths like fog masking a spotlight.

Astronomer Mikako Matsuura, also of Cardiff University, specializes in the study of dust and molecules in supernova remnants and is a co-author of this latest study. She commented:

Although the light from the neutron star is absorbed by the dust cloud that surrounds it, this in turn makes the cloud shine in sub-millimeter light, which we can now see with the extremely sensitive ALMA telescope. Our new findings will now enable astronomers to better understand how massive stars end their lives, leaving behind these extremely dense neutron stars.

Supernova 1987A was the brightest and closest supernova since Kepler’s supernova of 1604. It detonated on the edge of the Tarantula Nebula in the Large Magellanic Cloud. Since the supernova is some 168,000 light-years distant, the explosion actually occurred that long ago. Ian Shelton and Oscar Duhalde at the Las Campanas Observatory in Chile – and Albert Jones in New Zealand – were the first to spot the supernova in Earth’s skies in 1987.

A blue supergiant star called Sanduleak A had exploded, about which little was known. Astronomers were optimistic that by studying the event they could see if their theories about the death of massive stars were correct. The hope was that the supernova would leave behind a neutron star: better still, an easily detectable pulsar (all pulsars are neutron stars, but not all neutron stars are pulsars). If so, then the chain of events from core-collapse supernova explosion to neutron star could at last be verified. It was seen as something of a golden opportunity to confirm what we thought we knew about Type II supernovae and their aftermath.

But, as the initial glow subsided and astronomers in the Southern Hemisphere watched and waited, there were no radio bursts from a pulsar, no X-ray glow: there was nothing at all. It was soon realized that if there were any sort of star left behind at the center of the supernova remnant, it was behind huge quantities of dust, completely hidden from our view. Astronomers realized with disappointment, and the sense of something intensely valuable slipping from their grasp, that the dust would take a very long time to clear enough to reveal what it was masking. But there were also those who wondered, as the original mass of Sanduleak A was not known, if the reason there was no visible trace of any remnant was simply because what lurked in the dark, behind the wall of dust, was a new black hole.

And there was something quite unexpected about SN1987A, which was not realized until afterwards: about three hours before the explosion was seen in Chile, Japanese neutrino observatories had, between them, detected 25 neutrinos from the event. This was seen as confirmation that the bulk of neutrinos from supernovae are emitted some time before the star detonates. This pre-supernova detection of neutrinos can perhaps lay claim to be the first true multi-messenger astronomical event.

Apart from a brief flurry of excitement a few years after the supernova, as a group of radio astronomers thought they had detected brief pulsar emissions, nothing at the centre of the supernova remnant has been observed. The tentative pulsar signals were not confirmed nor repeated.

But now, at long last, astronomers have verification of their Type II supernova theories. The discovery demonstrates that astronomy is often a long and frustrating waiting game, where events play out over years and decades.

EarthSky 2020 lunar calendars are available! They make great gifts. Order now. Going fast!

Ring of green spots inside purple halo, with orange patch inside brightening toward the center.

Composite image of Supernova 1987A, via NASA/ ESA/ NRAO.

Bottom line: Astronomers using the ALMA radio telescope in Chile said in late 2019 that they’ve found the small, compact neutron star created in Supernova 1987A.

Source: High Angular Resolution ALMA Images of Dust and Molecules in the SN 1987A Ejecta

Via Cardiff University



from EarthSky https://ift.tt/2scXOxj
Aucun commentaire:
Libellés :

November 2019 was 2nd hottest on record for planet

World map with many large red spots and a few blue spots.

View larger. | An annotated map showing notable climate events that occurred around the world in November 2019. Image via NOAA.

A NOAA report, released December 16, 2019, says that November 2019 was the second-hottest November in the 140-year global climate record. In addition, the season (September-November) and the year to date (January-November) were both also the second hottest in recorded history, according to scientists at NOAA’s National Centers for Environmental Information.

The average global land and ocean surface temperature for November 2019 was 1.66 degrees F (0.92 C) above the 20th-century average. That’s just shy of November 2015, the warmest on record. All five of the planet’s hottest Novembers have occurred since 2013.

Read the full report.

World map mostly covered in red and pink areas.

View larger. | Image via NOAA.

In both the Arctic and Antarctic, sea ice coverage shrank to its second-lowest size on record for November, behind November 2016. According to the NOAA report, Arctic sea ice coverage was 12.8% below the 1981–2010 average, while the Antarctic coverage was 6.35% below average. The world’s average sea surface temperature ranked second warmest for the year to date – just 0.05 degree F (0.03 C) cooler than the record-breaking year of 2016.

Bottom line: NOAA reports that November 2019 was the second-hottest on record.

Via NOAA

EarthSky 2020 lunar calendars are available! They make great gifts. Order now. Going fast!



from EarthSky https://ift.tt/2MlF31C
World map with many large red spots and a few blue spots.

View larger. | An annotated map showing notable climate events that occurred around the world in November 2019. Image via NOAA.

A NOAA report, released December 16, 2019, says that November 2019 was the second-hottest November in the 140-year global climate record. In addition, the season (September-November) and the year to date (January-November) were both also the second hottest in recorded history, according to scientists at NOAA’s National Centers for Environmental Information.

The average global land and ocean surface temperature for November 2019 was 1.66 degrees F (0.92 C) above the 20th-century average. That’s just shy of November 2015, the warmest on record. All five of the planet’s hottest Novembers have occurred since 2013.

Read the full report.

World map mostly covered in red and pink areas.

View larger. | Image via NOAA.

In both the Arctic and Antarctic, sea ice coverage shrank to its second-lowest size on record for November, behind November 2016. According to the NOAA report, Arctic sea ice coverage was 12.8% below the 1981–2010 average, while the Antarctic coverage was 6.35% below average. The world’s average sea surface temperature ranked second warmest for the year to date – just 0.05 degree F (0.03 C) cooler than the record-breaking year of 2016.

Bottom line: NOAA reports that November 2019 was the second-hottest on record.

Via NOAA

EarthSky 2020 lunar calendars are available! They make great gifts. Order now. Going fast!



from EarthSky https://ift.tt/2MlF31C
Aucun commentaire:
Libellés :

Cassiopeia, Queen of the north

On these December evenings, turn toward the northern sky and see its famous constellation Cassiopeia the Queen. In early December, Cassiopeia swings directly over Polaris, the North Star, at roughly 7 p.m. local clock time. Cassiopeia – sometimes called The Lady of the Chair – is famous for having the shape of a telltale W or M. You will find this configuration of stars as a starlit M whenever she reigns highest in the sky, hovering over Polaris.

At this time of year, Cassiopeia can also be seen from tropical and subtropical latitudes in the Southern Hemisphere. From there, the constellation appears low in the north around 7 to 8 p.m. on early December evenings. As for Polaris … from the Southern Hemisphere, it’s below the horizon.

Because Cassiopeia returns to the same spot in the sky about four minutes earlier with each passing day, or 1/2 hour earlier with each passing week, look for Cassiopeia to be at her high point over Polaris, the North Star, around 6 p.m. in early January.

Starry sky with M-shaped lines and small oblong smudge that is a galaxy.

Zefri Besar in Brunei Darussalam caught Cassiopeia and the Andromeda galaxy in November 2016, using a DSLR camera and 50mm lens. Notice that – no matter how they are oriented in the sky – the deeper “V” of Cassiopeia points toward the galaxy.

From a dark country sky, you’ll see that Cassiopeia sits atop the luminous band of stars known as the Milky Way. Arching from horizon to horizon, this soft-glowing boulevard of stars represents an edgewise view into the flat disk of our own Milky Way galaxy. When Cassiopeia climbs above Polaris, the North Star, on these dark winter evenings, note that this hazy belt of stars that we call the Milky Way extends through the Northern Cross in the western sky and past Orion the Hunter in your eastern sky.

This Milky Way is fainter than the glorious broad band of the Milky Way we see in a Northern Hemisphere summer or Southern Hemisphere winter. That’s because, at the opposite side of the year, we are looking toward the star-rich center of the galaxy. On these December nights, we are looking toward the galaxy’s outer edge, not the center.

Diagram of Cassiopeia with arrow pointing to two small clusters.

The famous Double Cluster in the constellation Perseus is not far from Cassiopeia on the sky’s dome. This chart shows how to use the W or M shape of Cassiopeia to find the Double Cluster. To appreciate the clusters fully, look with your binoculars in a dark sky! More about the Double Cluster here.

As the night marches onward, Cassiopeia – like the hour hand of a clock – circles around the North Star, though in a counter-clockwise direction.

By dawn, you will find Cassiopeia has swept down in the northwest – to a point below the North Star. At that time, if you’re at a southerly latitude, such as the far south U.S., you might not be able to see Cassiopeia. The constellation might be below your horizon. But if you’re located at a latitude like those in the northern U.S., you will still see Cassiopeia sitting on or near your northern horizon.

Look northward on these cold December evenings to see Queen Cassiopeia sitting proudly on her throne, atop the northern terminus of the Milky Way!

Antique etching of woman in Grecian draperies sitting on a throne.

Queen Cassiopeia, aka The Lady of the Chair. Image via Hubble Source.

Bottom line: Watch for Cassiopeia the Queen on these December evenings. The constellation is shaped like an M or W. You’ll find Cassiopeia in the northeast at nightfall, sweeping higher in the north as evening progresses.

EarthSky lunar calendars are cool! They make great gifts. Order now. Going fast!

A planisphere is virtually indispensable for beginning stargazers. Order your EarthSky Planisphere today!



from EarthSky https://ift.tt/2zIlQk8

On these December evenings, turn toward the northern sky and see its famous constellation Cassiopeia the Queen. In early December, Cassiopeia swings directly over Polaris, the North Star, at roughly 7 p.m. local clock time. Cassiopeia – sometimes called The Lady of the Chair – is famous for having the shape of a telltale W or M. You will find this configuration of stars as a starlit M whenever she reigns highest in the sky, hovering over Polaris.

At this time of year, Cassiopeia can also be seen from tropical and subtropical latitudes in the Southern Hemisphere. From there, the constellation appears low in the north around 7 to 8 p.m. on early December evenings. As for Polaris … from the Southern Hemisphere, it’s below the horizon.

Because Cassiopeia returns to the same spot in the sky about four minutes earlier with each passing day, or 1/2 hour earlier with each passing week, look for Cassiopeia to be at her high point over Polaris, the North Star, around 6 p.m. in early January.

Starry sky with M-shaped lines and small oblong smudge that is a galaxy.

Zefri Besar in Brunei Darussalam caught Cassiopeia and the Andromeda galaxy in November 2016, using a DSLR camera and 50mm lens. Notice that – no matter how they are oriented in the sky – the deeper “V” of Cassiopeia points toward the galaxy.

From a dark country sky, you’ll see that Cassiopeia sits atop the luminous band of stars known as the Milky Way. Arching from horizon to horizon, this soft-glowing boulevard of stars represents an edgewise view into the flat disk of our own Milky Way galaxy. When Cassiopeia climbs above Polaris, the North Star, on these dark winter evenings, note that this hazy belt of stars that we call the Milky Way extends through the Northern Cross in the western sky and past Orion the Hunter in your eastern sky.

This Milky Way is fainter than the glorious broad band of the Milky Way we see in a Northern Hemisphere summer or Southern Hemisphere winter. That’s because, at the opposite side of the year, we are looking toward the star-rich center of the galaxy. On these December nights, we are looking toward the galaxy’s outer edge, not the center.

Diagram of Cassiopeia with arrow pointing to two small clusters.

The famous Double Cluster in the constellation Perseus is not far from Cassiopeia on the sky’s dome. This chart shows how to use the W or M shape of Cassiopeia to find the Double Cluster. To appreciate the clusters fully, look with your binoculars in a dark sky! More about the Double Cluster here.

As the night marches onward, Cassiopeia – like the hour hand of a clock – circles around the North Star, though in a counter-clockwise direction.

By dawn, you will find Cassiopeia has swept down in the northwest – to a point below the North Star. At that time, if you’re at a southerly latitude, such as the far south U.S., you might not be able to see Cassiopeia. The constellation might be below your horizon. But if you’re located at a latitude like those in the northern U.S., you will still see Cassiopeia sitting on or near your northern horizon.

Look northward on these cold December evenings to see Queen Cassiopeia sitting proudly on her throne, atop the northern terminus of the Milky Way!

Antique etching of woman in Grecian draperies sitting on a throne.

Queen Cassiopeia, aka The Lady of the Chair. Image via Hubble Source.

Bottom line: Watch for Cassiopeia the Queen on these December evenings. The constellation is shaped like an M or W. You’ll find Cassiopeia in the northeast at nightfall, sweeping higher in the north as evening progresses.

EarthSky lunar calendars are cool! They make great gifts. Order now. Going fast!

A planisphere is virtually indispensable for beginning stargazers. Order your EarthSky Planisphere today!



from EarthSky https://ift.tt/2zIlQk8
Aucun commentaire:
Libellés :

Don’t miss these cyclones on Jupiter, and more

A total of 7 cyclones - swirly circles. One is in the center. The other 6 are evenly spaced around it.

Jupiter’s south pole as seen from the Juno spacecraft on November 4, 2019. These swirling spots are cyclones at Jupiter’s pole. The whole hexagonal arrangement of cyclones is large enough to dwarf the Earth. The central cyclone can be compared to the continental U.S. The smallest one, in the lower right – a new one, seen for the first time in November – can be compared to Texas. Image via NASA/ JPL-Caltech/ SwRI/ ASI/ INAF/ JIRAM.

The Juno spacecraft – which has been orbiting the giant planet Jupiter since July of 2016 – acquires close-up images of the planet at every perijove, or closest point to Jupiter. That happens about every 53 days. The batch of images acquired by the craft in early November, when it swung to within 2,175 miles (3,500 km) of the cloudtops at Jupiter’s south pole, are particularly mind-blowing. The big news for the November flyby … the craft discovered that Jupiter’s south pole has seven large, well defined cyclones now, instead of the six seen previously. These cyclones appear in a hexagonal (six-sided) pattern at Jupiter’s pole, rather than the pentagonal (five-sided) pattern seen previously. A statement from NASA explained:

When Juno first arrived at Jupiter in July 2016, its infrared and visible-light cameras discovered giant cyclones encircling the planet’s poles – nine in the north and six in the south. Were they, like their Earthly siblings, a transient phenomenon, taking only weeks to develop and then ebb? Or could these cyclones, each nearly as wide as the continental U.S., be more permanent fixtures?

With each flyby, the data reinforced the idea that five windstorms were swirling in a pentagonal pattern around a central storm at the south pole and that the system seemed stable. None of the six storms showed signs of yielding to allow other cyclones to join in …

Then, during Juno’s 22nd science pass, a new, smaller cyclone churned to life and joined the fray.

Alessandro Mura, a Juno co-investigator at the National Institute for Astrophysics in Rome, said:

Data from Juno’s Jovian Infrared Auroral Mapper [JIRAM] instrument indicates we went from a pentagon of cyclones surrounding one at the center to a hexagonal arrangement.

This new addition is smaller in stature than its six more established cyclonic brothers: It’s about the size of Texas.

Maybe JIRAM data from future flybys will show the cyclone growing to the same size as its neighbors.

EarthSky 2020 lunar calendars are available! They make great gifts. Order now. Going fast!

Six cyclones at Jupiter's south pole, with lines drawn to indicate their hexagonal pattern.

Jupiter’s pentagon turns hexagon. In this annotated infrared image, 6 cyclones form a hexagonal pattern around a central cyclone at Jupiter’s south pole. That’s in contrast to the 5 cyclones in a pentagonal shape seen previously. NASA/ JPL-Caltech/ SwRI/ ASI/ INAF/ JIRAM.

Outline of the continental U.S. about the size of the central cyclone and Texas of the smallest one.

To give some sense of the immense scale of cyclones arranged in a hexagonal pattern at Jupiter’s south pole, an outline of the continental United States is superimposed over the central cyclone and an outline of Texas is superimposed over the newest cyclone. The hexagonal arrangement of the cyclones is large enough to dwarf the Earth. This JIRAM image was obtained during the 23rd science pass of the Juno spacecraft over Jupiter, on November 4, 2019. Image via NASA/ JPL-Caltech/ SwRI/ ASI/ INAF/ JIRAM.

NASA said the flyby:

… also marked a victory for the mission team, whose innovative measures kept the solar-powered spacecraft clear of what could have been a mission-ending eclipse.

To understand what happened, you have to go back to Juno’s entry into orbit around Jupiter on July 4, 2016. It was meant to enter an initial 53-day orbit, then reduce the size of its orbit a few months later, in order to shorten the period between science flybys to every 14 days. But the project team recommended to NASA to forgo the main engine burn due to concerns about the spacecraft’s fuel delivery system.

Now Juno is carrying out its mission, NASA said, although it’s taking longer than originally plannned. But Juno’s longer life at Jupiter is what led to the need to avoid Jupiter’s shadow. Steve Levin, Juno project scientist at NASA’s Jet Propulsion Laboratory in Pasadena, California, explained:

Ever since the day we entered orbit around Jupiter, we made sure it remained bathed in sunlight 24/7. Our navigators and engineers told us a day of reckoning was coming, when we would go into Jupiter’s shadow for about 12 hours. We knew that for such an extended period without power, our spacecraft would suffer a similar fate as the Opportunity rover, when the skies of Mars filled with dust and blocked the sun’s rays from reaching its solar panels.

A crescent Jupiter, with Io's oval black shadow on its cloudtops.

View larger. | In this image, you can see a shadow on Jupiter, cast by its moon Io. Io’s shadow can be seen on Jupiter through earthly telescopes, and many pictures have been taken of it from space as well, but this is the first from such a close distance, just 8,450 miles (13,600 kilometers) above Jupiter’s cloudtops. JunoCam acquired this image on September 12, 2019. Image via NASA/ JPL-Caltech/ SwRI/ MSSS. Image processing by citizen scientist Tanya Oleksuik.

NASA explained that, without the sun’s rays providing power, Juno would be chilled below tested levels. The space scientists believed that – during this time – Juno’s battery cells would be drained beyond recovery. So the navigation team set devised a plan to “jump the shadow,” maneuvering the spacecraft just enough so its trajectory would miss the eclipse. NASA said:

The navigators calculated that if Juno performed a rocket burn weeks in advance of November 3, while the spacecraft was as far in its orbit from Jupiter as it gets, they could modify its trajectory enough to give the eclipse the slip. The maneuver would utilize the spacecraft’s reaction control system, which wasn’t initially intended to be used for a maneuver of this size and duration.

On September 30, at 7:46 p.m. EDT (4:46 p.m. PDT), the reaction control system burn began. It ended 10 ½ hours later. The propulsive maneuver — five times longer than any previous use of that system — changed Juno’s orbital velocity by 126 mph (203 kph) and consumed about 160 pounds (73 kilograms) of fuel.

Thirty-four days later, the spacecraft’s solar arrays continued to convert sunlight into electrons unabated as Juno prepared to scream once again over Jupiter’s cloud tops.

Scott Bolton, Juno principal investigator from the Southwest Research Institute in San Antonio, explained:

The combination of creativity and analytical thinking has once again paid off big time for NASA … While the team was trying to figure out how to conserve energy and keep our core heated, the engineers came up with a completely new way out of the problem: Jump Jupiter’s shadow.

It was nothing less than a navigation stroke of genius. Lo and behold, first thing out of the gate on the other side, we make another fundamental discovery.

As you read this, Juno is heading toward its next perijove on December 26, 2019. Watch for news and new images shortly after the new year dawns!

A swirling blue and white hurricane-like vortex on Jupiter.

View larger. | Swirls and storms in Jupiter’s clouds. This image of a vortex on Jupiter, taken by the Juno mission camera, JunoCam, captures the amazing internal structure of the giant storm. Original image taken on November 3, 2019, at an altitude of approximately 5,300 miles (8,600 km) and a latitude of about 48 degrees north on Jupiter. Image via NASA/ JPL-Caltech/ SwRI/ MSSS/ Junocam. Image processing by citizen scientists Gerald Eichstädt/ Seán Doran.

A whole Jupiter, with detailed swirls.

In this amazing Juno image, south is up. The original image was captured by JunoCam on September 12, 2019. Image via NASA/ JPL-Caltech/ SwRI/ MSSS/ JunoCam. Image processing by citizen scientist Prateek Sarpal, who titled this “A mind of limits, a camera of thoughts.”

Bottom line: On its last flyby close to Jupiter – on November 4, 2019 – the Juno spacecraft discovered a new small cyclone at Jupiter’s south pole.

See all the latest images from NASA’s Juno spacecraft

Via NASA



from EarthSky https://ift.tt/2SiRWx2
A total of 7 cyclones - swirly circles. One is in the center. The other 6 are evenly spaced around it.

Jupiter’s south pole as seen from the Juno spacecraft on November 4, 2019. These swirling spots are cyclones at Jupiter’s pole. The whole hexagonal arrangement of cyclones is large enough to dwarf the Earth. The central cyclone can be compared to the continental U.S. The smallest one, in the lower right – a new one, seen for the first time in November – can be compared to Texas. Image via NASA/ JPL-Caltech/ SwRI/ ASI/ INAF/ JIRAM.

The Juno spacecraft – which has been orbiting the giant planet Jupiter since July of 2016 – acquires close-up images of the planet at every perijove, or closest point to Jupiter. That happens about every 53 days. The batch of images acquired by the craft in early November, when it swung to within 2,175 miles (3,500 km) of the cloudtops at Jupiter’s south pole, are particularly mind-blowing. The big news for the November flyby … the craft discovered that Jupiter’s south pole has seven large, well defined cyclones now, instead of the six seen previously. These cyclones appear in a hexagonal (six-sided) pattern at Jupiter’s pole, rather than the pentagonal (five-sided) pattern seen previously. A statement from NASA explained:

When Juno first arrived at Jupiter in July 2016, its infrared and visible-light cameras discovered giant cyclones encircling the planet’s poles – nine in the north and six in the south. Were they, like their Earthly siblings, a transient phenomenon, taking only weeks to develop and then ebb? Or could these cyclones, each nearly as wide as the continental U.S., be more permanent fixtures?

With each flyby, the data reinforced the idea that five windstorms were swirling in a pentagonal pattern around a central storm at the south pole and that the system seemed stable. None of the six storms showed signs of yielding to allow other cyclones to join in …

Then, during Juno’s 22nd science pass, a new, smaller cyclone churned to life and joined the fray.

Alessandro Mura, a Juno co-investigator at the National Institute for Astrophysics in Rome, said:

Data from Juno’s Jovian Infrared Auroral Mapper [JIRAM] instrument indicates we went from a pentagon of cyclones surrounding one at the center to a hexagonal arrangement.

This new addition is smaller in stature than its six more established cyclonic brothers: It’s about the size of Texas.

Maybe JIRAM data from future flybys will show the cyclone growing to the same size as its neighbors.

EarthSky 2020 lunar calendars are available! They make great gifts. Order now. Going fast!

Six cyclones at Jupiter's south pole, with lines drawn to indicate their hexagonal pattern.

Jupiter’s pentagon turns hexagon. In this annotated infrared image, 6 cyclones form a hexagonal pattern around a central cyclone at Jupiter’s south pole. That’s in contrast to the 5 cyclones in a pentagonal shape seen previously. NASA/ JPL-Caltech/ SwRI/ ASI/ INAF/ JIRAM.

Outline of the continental U.S. about the size of the central cyclone and Texas of the smallest one.

To give some sense of the immense scale of cyclones arranged in a hexagonal pattern at Jupiter’s south pole, an outline of the continental United States is superimposed over the central cyclone and an outline of Texas is superimposed over the newest cyclone. The hexagonal arrangement of the cyclones is large enough to dwarf the Earth. This JIRAM image was obtained during the 23rd science pass of the Juno spacecraft over Jupiter, on November 4, 2019. Image via NASA/ JPL-Caltech/ SwRI/ ASI/ INAF/ JIRAM.

NASA said the flyby:

… also marked a victory for the mission team, whose innovative measures kept the solar-powered spacecraft clear of what could have been a mission-ending eclipse.

To understand what happened, you have to go back to Juno’s entry into orbit around Jupiter on July 4, 2016. It was meant to enter an initial 53-day orbit, then reduce the size of its orbit a few months later, in order to shorten the period between science flybys to every 14 days. But the project team recommended to NASA to forgo the main engine burn due to concerns about the spacecraft’s fuel delivery system.

Now Juno is carrying out its mission, NASA said, although it’s taking longer than originally plannned. But Juno’s longer life at Jupiter is what led to the need to avoid Jupiter’s shadow. Steve Levin, Juno project scientist at NASA’s Jet Propulsion Laboratory in Pasadena, California, explained:

Ever since the day we entered orbit around Jupiter, we made sure it remained bathed in sunlight 24/7. Our navigators and engineers told us a day of reckoning was coming, when we would go into Jupiter’s shadow for about 12 hours. We knew that for such an extended period without power, our spacecraft would suffer a similar fate as the Opportunity rover, when the skies of Mars filled with dust and blocked the sun’s rays from reaching its solar panels.

A crescent Jupiter, with Io's oval black shadow on its cloudtops.

View larger. | In this image, you can see a shadow on Jupiter, cast by its moon Io. Io’s shadow can be seen on Jupiter through earthly telescopes, and many pictures have been taken of it from space as well, but this is the first from such a close distance, just 8,450 miles (13,600 kilometers) above Jupiter’s cloudtops. JunoCam acquired this image on September 12, 2019. Image via NASA/ JPL-Caltech/ SwRI/ MSSS. Image processing by citizen scientist Tanya Oleksuik.

NASA explained that, without the sun’s rays providing power, Juno would be chilled below tested levels. The space scientists believed that – during this time – Juno’s battery cells would be drained beyond recovery. So the navigation team set devised a plan to “jump the shadow,” maneuvering the spacecraft just enough so its trajectory would miss the eclipse. NASA said:

The navigators calculated that if Juno performed a rocket burn weeks in advance of November 3, while the spacecraft was as far in its orbit from Jupiter as it gets, they could modify its trajectory enough to give the eclipse the slip. The maneuver would utilize the spacecraft’s reaction control system, which wasn’t initially intended to be used for a maneuver of this size and duration.

On September 30, at 7:46 p.m. EDT (4:46 p.m. PDT), the reaction control system burn began. It ended 10 ½ hours later. The propulsive maneuver — five times longer than any previous use of that system — changed Juno’s orbital velocity by 126 mph (203 kph) and consumed about 160 pounds (73 kilograms) of fuel.

Thirty-four days later, the spacecraft’s solar arrays continued to convert sunlight into electrons unabated as Juno prepared to scream once again over Jupiter’s cloud tops.

Scott Bolton, Juno principal investigator from the Southwest Research Institute in San Antonio, explained:

The combination of creativity and analytical thinking has once again paid off big time for NASA … While the team was trying to figure out how to conserve energy and keep our core heated, the engineers came up with a completely new way out of the problem: Jump Jupiter’s shadow.

It was nothing less than a navigation stroke of genius. Lo and behold, first thing out of the gate on the other side, we make another fundamental discovery.

As you read this, Juno is heading toward its next perijove on December 26, 2019. Watch for news and new images shortly after the new year dawns!

A swirling blue and white hurricane-like vortex on Jupiter.

View larger. | Swirls and storms in Jupiter’s clouds. This image of a vortex on Jupiter, taken by the Juno mission camera, JunoCam, captures the amazing internal structure of the giant storm. Original image taken on November 3, 2019, at an altitude of approximately 5,300 miles (8,600 km) and a latitude of about 48 degrees north on Jupiter. Image via NASA/ JPL-Caltech/ SwRI/ MSSS/ Junocam. Image processing by citizen scientists Gerald Eichstädt/ Seán Doran.

A whole Jupiter, with detailed swirls.

In this amazing Juno image, south is up. The original image was captured by JunoCam on September 12, 2019. Image via NASA/ JPL-Caltech/ SwRI/ MSSS/ JunoCam. Image processing by citizen scientist Prateek Sarpal, who titled this “A mind of limits, a camera of thoughts.”

Bottom line: On its last flyby close to Jupiter – on November 4, 2019 – the Juno spacecraft discovered a new small cyclone at Jupiter’s south pole.

See all the latest images from NASA’s Juno spacecraft

Via NASA



from EarthSky https://ift.tt/2SiRWx2
Aucun commentaire:
Libellés :

Next new moon is December 26

Extremely thin, threadlike crescent against blue background.

Youngest possible lunar crescent, with the moon’s age being exactly zero when this photo was taken — at the instant of new moon – 07:14 UTC on July 8, 2013. Image by Thierry Legault.

When the moon is new, it’s most nearly between the Earth and sun for any particular month. There’s a new moon about once a month, because the moon takes about a month to orbit Earth. Most of the time, the new moon passes not in front of the sun, but simply near it in our sky. That’s why, in most months, there’s no solar eclipse. In December 2019, however, an eclipse does occur. It’s an annular or “ring” eclipse – the only one of 2019 – visible from Earth’s Eastern Hemisphere.

Read more: Annular solar eclipse of December 26

The moon must be at the new phase in order for a solar eclipse to take place.

The photo of a new moon at the top of this page shows the moon as it passed near the sun on July 8, 2013. There was no eclipse that day; it was an ordinary new moon. New moons typically can’t be seen, or at least they can’t without special equipment and a lot of moon-photography experience. Thierry Legault was able to catch the photo at top – the moon at the instant it was new – because the moon that month passed to one side of the sun, and the faintest of lunar crescents was visible.

Either way – in front of the sun or just near it – on the day of new moon, the moon travels across the sky with the sun during the day, hidden in the sun’s glare.

Some people use the term new moon for a thin crescent moon visible in the west after sunset. You always see these little crescents – which set shortly after the sun – a day or two after each month’s new moon. Astronomers don’t call these little crescent moons new moons, however. In the language of astronomy, this slim crescent is called a young moon.

New moons, and young moons, are fascinating to many. The Farmer’s Almanac, for example, still offers information on gardening by the moon. And many cultures have holidays based on moon phases.

Positions of waxing crescent moon on different days along ecliptic near star Spica.

Start looking for the young moon – a slim crescent visible in the west after sunset – around August 31, 2019. Read more.

Bottom line: New moons generally can’t be seen. They cross the sky with the sun during the day. The next new moon happens on December 26 at 5:13 UTC. It will cause an annular or ring eclipse, visible from Earth’s Eastern Hemisphere.

Read more: Year’s closest new supermoon on August 30

Read more: What’s the youngest moon you can see?

Read more: 4 keys to understanding moon phases

Help EarthSky keep going! Please donate.



from EarthSky https://ift.tt/2QpMvsB
Extremely thin, threadlike crescent against blue background.

Youngest possible lunar crescent, with the moon’s age being exactly zero when this photo was taken — at the instant of new moon – 07:14 UTC on July 8, 2013. Image by Thierry Legault.

When the moon is new, it’s most nearly between the Earth and sun for any particular month. There’s a new moon about once a month, because the moon takes about a month to orbit Earth. Most of the time, the new moon passes not in front of the sun, but simply near it in our sky. That’s why, in most months, there’s no solar eclipse. In December 2019, however, an eclipse does occur. It’s an annular or “ring” eclipse – the only one of 2019 – visible from Earth’s Eastern Hemisphere.

Read more: Annular solar eclipse of December 26

The moon must be at the new phase in order for a solar eclipse to take place.

The photo of a new moon at the top of this page shows the moon as it passed near the sun on July 8, 2013. There was no eclipse that day; it was an ordinary new moon. New moons typically can’t be seen, or at least they can’t without special equipment and a lot of moon-photography experience. Thierry Legault was able to catch the photo at top – the moon at the instant it was new – because the moon that month passed to one side of the sun, and the faintest of lunar crescents was visible.

Either way – in front of the sun or just near it – on the day of new moon, the moon travels across the sky with the sun during the day, hidden in the sun’s glare.

Some people use the term new moon for a thin crescent moon visible in the west after sunset. You always see these little crescents – which set shortly after the sun – a day or two after each month’s new moon. Astronomers don’t call these little crescent moons new moons, however. In the language of astronomy, this slim crescent is called a young moon.

New moons, and young moons, are fascinating to many. The Farmer’s Almanac, for example, still offers information on gardening by the moon. And many cultures have holidays based on moon phases.

Positions of waxing crescent moon on different days along ecliptic near star Spica.

Start looking for the young moon – a slim crescent visible in the west after sunset – around August 31, 2019. Read more.

Bottom line: New moons generally can’t be seen. They cross the sky with the sun during the day. The next new moon happens on December 26 at 5:13 UTC. It will cause an annular or ring eclipse, visible from Earth’s Eastern Hemisphere.

Read more: Year’s closest new supermoon on August 30

Read more: What’s the youngest moon you can see?

Read more: 4 keys to understanding moon phases

Help EarthSky keep going! Please donate.



from EarthSky https://ift.tt/2QpMvsB
Aucun commentaire:
Libellés :

Europe’s CHEOPS mission will shed light on strange new worlds

Spacecraft with large sun-like star and planets in background.

Artist’s concept of the just-launched CHEOPS space telescope, which will study hundreds of exoplanets in greater detail than ever before. Image via ESA/ ATG medialab/ DLR.

After a one-day delay, the European Space Agency (ESA) successfully launched its CHEOPS mission last week, on the morning of December 18, 2019, from the spaceport in Kourou, French Guiana. CHEOPS is the first ESA mission dedicated to studying exoplanets, those distant worlds orbiting other stars. NASA’s planet-hunting space missions, first Kepler and now TESS, have been finding new exoplanets. CHEOPS will study hundreds of exoplanets already known to exist – out of 4,000-plus now confirmed – to determine their sizes, masses, densities and possible atmospheres.

In this way, CHEOPS will take us some steps along the road of finding out what many exoworlds are actually like, not an easy task.

CHEOPS stands for CHaracterising ExOPlanets Satellite. The telescope will reside in a sun-synchronous orbit around Earth at an altitude of more than 400 miles (700 km). Kate Isaak, CHEOPS project scientist, said in a statement:

We are very excited to see the satellite blast off into space. There are so many interesting exoplanets and we will be following up on several hundreds of them, focusing in particular on the smaller planets in the size range between Earth and Neptune. They seem to be the commonly found planets in our Milky Way galaxy, yet we do not know much about them. CHEOPS will help us reveal the mysteries of these fascinating worlds, and take us one step closer to answering one of the most profound questions we humans ponder: are we alone in the universe?

Watch the launch below:

Heike Rauer, Director of the DLR Institute of Planetary Research in Berlin, said:

More than 4000 exoplanets have been discovered in the Milky Way, yet we still know far too little about these distant worlds in our cosmic neighborhood. We are all eager to see which ‘faces’ the planets characterized by CHEOPS will show us.

So how does CHEOPS observe these planets?

Like some other telescopes, it will watch as the planets transit in front of their stars, as seen from Earth. As Juan Cabrera Perez, Head of the Extrasolar Planets and Atmospheres Department at the DLR Institute of Planetary Research, explained:

We could describe this fluctuation in brightness as a ‘mini stellar eclipse’, as the transiting exoplanet reduces the intensity of the light from the star for a short time. This fluctuation can be measured and analyzed – an area in which we can contribute suitable tools and many years of experience.

EarthSky 2020 lunar calendars are available! They make great gifts. Order now. Going fast!

Rocket launch from low angle with flame beneath rocket and many bright spots in foreground.

Cool photo of CHEOPS launch, December 18, 2019. Image via ESA/ S. Corvaja.

CHEOPS will focus on some of the most common exoplanets discovered so far, ranging in size from Earth to Neptune, or about approximately 6,000 to 30,000 miles (10,000 to 50,000 km) in diameter. Using data from the transits, CHEOPS can determine the size, mass and density of the planets. All of these are important in order for scientists to figure out the planets’ compositions. Some will be rocky like Earth, while others will have deep, gaseous atmospheres like Neptune or even Jupiter or Saturn. Knowing this will also help scientists determine which of these worlds might be potentially habitable. Of course, rocky planets similar in size to Earth, or a bit larger – super-Earths – would be the most interesting in this regard. Nicola Rando, CHEOPS project manager, said:

Both CHEOPS instrument and spacecraft are built to be extremely stable, so as to measure the incredibly small variations in the light of distant stars as their planets transit in front of them. For a planet like Earth, this amounts to the equivalent of watching the sun from a distant star and measuring its light dim by a tiny fraction of a percent. Now we are looking forward to the first part of the operational activities, making sure that the satellite and instrument perform as expected, ready for scientists to perform their world-class science.

CHEOPS will also be able to find out which of these planets do have atmospheres and whether they have clouds. This will help differentiate between deep, gaseous primordial atmospheres with no real solid surface between them, and thinner atmospheres like those on terrestrial planets such as Earth, Venus or Mars.

CHEOPS is just the first of three planned ESA missions to study exoplanets.

The Planetary Transits and Oscillations of stars (PLATO) space telescope, expected to launch in 2026, will focus on searching for “Earth-like” planets, ones that are rocky and about the same size as Earth orbiting in their stars’ habitable zones. So far, most such worlds have been found orbiting red dwarf stars, the most common type of star in our galaxy. CHEOPS, however, will look for these planets around sun-like stars. It will also be able to determine the age of these planetary systems with more accuracy than possible before.

A couple of years later, in 2028, ESA will launch the Atmospheric Remote-sensing Infrared Exoplanet Large-survey (ARIEL) mission, which will study the atmospheres of exoplanets. As well as atmospheric composition, this will help scientists develop a comprehensive catalog of exoplanetary orbits, radii, masses, densities and ages.

All three of these exciting missions, and others, will greatly increase our knowledge of these exotic, far-off worlds.

Diagrams of spacecraft with text annotations on black background.

View larger. | Timeline of ESA and NASA exoplanet missions, including CHEOPS. Image via ESA.

As Günther Hasinger, ESA Director of Science, said:

CHEOPS will take exoplanet science to a whole new level. After the discovery of thousands of planets, the quest can now turn to characterization, investigating the physical and chemical properties of many exoplanets and really getting to know what they are made of and how they formed. CHEOPS will also pave the way for our future exoplanet missions, from the international James Webb Telescope to ESA’s very own PLATO and ARIEL satellites, keeping European science at the forefront of exoplanet research.

The CHEOPS mission is a partnership between ESA and Switzerland with additional contributions from Austria, Belgium, France, Germany, Hungary, Italy, Portugal, Spain, Sweden and the U.K. More than 100 scientists and engineers are involved. The nominal mission is expected to last 3 1/2 years. While the CHEOPS science team has the bulk of observation time, 20% of the time is reserved for other scientists from around the world.

CHEOPS and the coming follow-up missions will open an exciting new chapter in exoplanetary study. What fascinating discoveries will they make?

Bottom line: ESA has successfully launched its CHEOPS space telescope to study hundreds of exoplanets in more detail than ever before.

Via ESA

Via German Aerospace Center (DLR)

Read more: Visit CHEOPS website



from EarthSky https://ift.tt/2ZkxxJx
Spacecraft with large sun-like star and planets in background.

Artist’s concept of the just-launched CHEOPS space telescope, which will study hundreds of exoplanets in greater detail than ever before. Image via ESA/ ATG medialab/ DLR.

After a one-day delay, the European Space Agency (ESA) successfully launched its CHEOPS mission last week, on the morning of December 18, 2019, from the spaceport in Kourou, French Guiana. CHEOPS is the first ESA mission dedicated to studying exoplanets, those distant worlds orbiting other stars. NASA’s planet-hunting space missions, first Kepler and now TESS, have been finding new exoplanets. CHEOPS will study hundreds of exoplanets already known to exist – out of 4,000-plus now confirmed – to determine their sizes, masses, densities and possible atmospheres.

In this way, CHEOPS will take us some steps along the road of finding out what many exoworlds are actually like, not an easy task.

CHEOPS stands for CHaracterising ExOPlanets Satellite. The telescope will reside in a sun-synchronous orbit around Earth at an altitude of more than 400 miles (700 km). Kate Isaak, CHEOPS project scientist, said in a statement:

We are very excited to see the satellite blast off into space. There are so many interesting exoplanets and we will be following up on several hundreds of them, focusing in particular on the smaller planets in the size range between Earth and Neptune. They seem to be the commonly found planets in our Milky Way galaxy, yet we do not know much about them. CHEOPS will help us reveal the mysteries of these fascinating worlds, and take us one step closer to answering one of the most profound questions we humans ponder: are we alone in the universe?

Watch the launch below:

Heike Rauer, Director of the DLR Institute of Planetary Research in Berlin, said:

More than 4000 exoplanets have been discovered in the Milky Way, yet we still know far too little about these distant worlds in our cosmic neighborhood. We are all eager to see which ‘faces’ the planets characterized by CHEOPS will show us.

So how does CHEOPS observe these planets?

Like some other telescopes, it will watch as the planets transit in front of their stars, as seen from Earth. As Juan Cabrera Perez, Head of the Extrasolar Planets and Atmospheres Department at the DLR Institute of Planetary Research, explained:

We could describe this fluctuation in brightness as a ‘mini stellar eclipse’, as the transiting exoplanet reduces the intensity of the light from the star for a short time. This fluctuation can be measured and analyzed – an area in which we can contribute suitable tools and many years of experience.

EarthSky 2020 lunar calendars are available! They make great gifts. Order now. Going fast!

Rocket launch from low angle with flame beneath rocket and many bright spots in foreground.

Cool photo of CHEOPS launch, December 18, 2019. Image via ESA/ S. Corvaja.

CHEOPS will focus on some of the most common exoplanets discovered so far, ranging in size from Earth to Neptune, or about approximately 6,000 to 30,000 miles (10,000 to 50,000 km) in diameter. Using data from the transits, CHEOPS can determine the size, mass and density of the planets. All of these are important in order for scientists to figure out the planets’ compositions. Some will be rocky like Earth, while others will have deep, gaseous atmospheres like Neptune or even Jupiter or Saturn. Knowing this will also help scientists determine which of these worlds might be potentially habitable. Of course, rocky planets similar in size to Earth, or a bit larger – super-Earths – would be the most interesting in this regard. Nicola Rando, CHEOPS project manager, said:

Both CHEOPS instrument and spacecraft are built to be extremely stable, so as to measure the incredibly small variations in the light of distant stars as their planets transit in front of them. For a planet like Earth, this amounts to the equivalent of watching the sun from a distant star and measuring its light dim by a tiny fraction of a percent. Now we are looking forward to the first part of the operational activities, making sure that the satellite and instrument perform as expected, ready for scientists to perform their world-class science.

CHEOPS will also be able to find out which of these planets do have atmospheres and whether they have clouds. This will help differentiate between deep, gaseous primordial atmospheres with no real solid surface between them, and thinner atmospheres like those on terrestrial planets such as Earth, Venus or Mars.

CHEOPS is just the first of three planned ESA missions to study exoplanets.

The Planetary Transits and Oscillations of stars (PLATO) space telescope, expected to launch in 2026, will focus on searching for “Earth-like” planets, ones that are rocky and about the same size as Earth orbiting in their stars’ habitable zones. So far, most such worlds have been found orbiting red dwarf stars, the most common type of star in our galaxy. CHEOPS, however, will look for these planets around sun-like stars. It will also be able to determine the age of these planetary systems with more accuracy than possible before.

A couple of years later, in 2028, ESA will launch the Atmospheric Remote-sensing Infrared Exoplanet Large-survey (ARIEL) mission, which will study the atmospheres of exoplanets. As well as atmospheric composition, this will help scientists develop a comprehensive catalog of exoplanetary orbits, radii, masses, densities and ages.

All three of these exciting missions, and others, will greatly increase our knowledge of these exotic, far-off worlds.

Diagrams of spacecraft with text annotations on black background.

View larger. | Timeline of ESA and NASA exoplanet missions, including CHEOPS. Image via ESA.

As Günther Hasinger, ESA Director of Science, said:

CHEOPS will take exoplanet science to a whole new level. After the discovery of thousands of planets, the quest can now turn to characterization, investigating the physical and chemical properties of many exoplanets and really getting to know what they are made of and how they formed. CHEOPS will also pave the way for our future exoplanet missions, from the international James Webb Telescope to ESA’s very own PLATO and ARIEL satellites, keeping European science at the forefront of exoplanet research.

The CHEOPS mission is a partnership between ESA and Switzerland with additional contributions from Austria, Belgium, France, Germany, Hungary, Italy, Portugal, Spain, Sweden and the U.K. More than 100 scientists and engineers are involved. The nominal mission is expected to last 3 1/2 years. While the CHEOPS science team has the bulk of observation time, 20% of the time is reserved for other scientists from around the world.

CHEOPS and the coming follow-up missions will open an exciting new chapter in exoplanetary study. What fascinating discoveries will they make?

Bottom line: ESA has successfully launched its CHEOPS space telescope to study hundreds of exoplanets in more detail than ever before.

Via ESA

Via German Aerospace Center (DLR)

Read more: Visit CHEOPS website



from EarthSky https://ift.tt/2ZkxxJx
Aucun commentaire:
Libellés :
Inscription à : Articles (Atom)