When is the next Blue Moon?

Most Blue Moons are not blue in color. This photo of a moon among fast-moving clouds was created using special blue filters. Image via our friend Jv Noriega.

The next Blue Moon will come on October 31, 2020. It’ll be called a Blue Moon because it’ll be the second of two full moons to occur in a single calendar month. The last Blue Moon by this definition of the term happened on March 31, 2018.

There’s another definition for Blue Moon. It can be the third of four full moons in a single season, with a season being between a solstice and equinox. The next seasonal Blue Moon will be August 22, 2021.

In recent years, people have been using the name Blue Moon for these two different sorts of moons: second of two full moons in a calendar month, or third of four full moons in a single season.

Someday, you might see an actual blue-colored moon. Meanwhile, the moon you’ll see on October 31, 2020, likely won’t look blue, and blue-colored moons in photos – like the ones on this page – are usually made using special blue camera filters or in a post-processing program such as PhotoShop.

EarthSky 2020 lunar calendars are available! Nearly sold out. Order now!

The Virtual Telescope Project in Rome, Italy, hosted a live viewing of the May 18, 2019, full moon rising above the Rome skyline.

Let’s talk about seasonal Blue Moons first. A year has 12 months, and months – or “moonths” – have lengths more or less based on a single orbit of the moon around Earth. What we call a season – winter, spring, summer, fall – typically lasts three months, and typically has three full moons.

If a season has four full moons, then the third full moon may be called a Blue Moon, according to the old Maine Farmer’s Almanac. There was a Blue Moon by this definition on November 21, 2010, another on August 20-21, 2013, another on May 21, 2016, and another on May 18, 2019. The next will be on August 22, 2021.

Desert Blue Moon from our friend Priya Kumar in Oman, August 2012. Thank you, Priya!

The best-known and most popular definition of Blue Moon is that it describes the second full moon of a calendar month. By this definition, there was a Blue Moon on July 31, 2015, January 31, 2018, and March 31, 2018. The next one will be October 31, 2020.

The time between one full moon and the next is close to the length of a calendar month. So the only time one month can have two full moons is when the first full moon happens in the first few days of the month. This happens every two to three years, so these sorts of Blue Moons come about that often.

Very rarely, a seasonal Blue Moon (third of four full moons in one season) and a monthly Blue Moon (second of two full moons in one calendar month) can occur in the same calendar year. For this to happen, you need 13 full moons between successive December solstices for a seasonal Blue Moon – and, generally, 13 full moons in one calendar year for a monthly Blue Moon.

This will next happen in the year 2048, when a monthly Blue Moon falls on January 31, and a seasonal Blue Moon on August 23.

Then 19 years later, in the year 2067, there will be a monthly Blue Moon on March 30, and a seasonal Blue Moon on November 20. In this instance, there are 13 full moons between successive December solstices – but only 12 full moons in one calendar year and no February 2067 full moon.

Blue moons don’t really look blue in color. Greg Hogan got this shot of a Blue Moon (blue in name only!) on July 31, 2015. He wrote: “Having some fun with the blue moon idea……I blended the same image twice one with a blue tint, and one normal. :) “

The idea of a Blue Moon as the second full moon in a month stemmed from the March 1946 issue of Sky and Telescope magazine, which contained an article called Once in a Blue Moon by James Hugh Pruett. Pruett was referring to the 1937 Maine Farmer’s Almanac, but he inadvertently simplified the definition. He wrote:

Seven times in 19 years there were – and still are – 13 full moons in a year. This gives 11 months with one full moon each and one with two. This second in a month, so I interpret it, was called Blue Moon.

Had James Hugh Pruett looked at the actual date of the 1937 Blue Moon, he would have found that it had occurred August 21, 1937. Also, there were only 12 full moons in 1937. You generally need 13 full moons in one calendar year to have two full moons in one calendar month.

However, that fortuitous oversight gave birth to a new and perfectly understandable definition for Blue Moon.

EarthSky’s Deborah Byrd happened upon a copy of this old 1946 issue of Sky and Telescope in the stacks of the Peridier Library at the University of Texas Astronomy Department in the late 1970s. Afterward, she began using the term Blue Moon to describe the second full moon in a calendar month on the radio. Later, this definition of Blue Moon was also popularized by a book for children by Margot McLoon-Basta and Alice Siegel, called Kids’ World Almanac of Records and Facts, published in New York by World Almanac Publications in 1985. The second-full-moon-in-a-month definition was also used in the board game Trivial Pursuit.

Today, it has become part of folklore. As the folklorist Philip Hiscock wrote in his comprehensive article Once in a Blue Moon:

‘Old folklore’ it is not, but real folklore it is.

This photo was created using special blue filters, too. Image via EarthSky Facebook friend Jv Noriega.

Can a moon be blue in color? Yes, but it’s very rare to see a blue-colored moon. You need unusual sky conditions – certain-sized particles of dust or smoke – to create them.

Blue-colored moons aren’t predictable. So don’t be misled by the photos above. The sorts of moons people commonly call Blue Moons aren’t usually blue.

For more about truly blue-colored moons, click here.

Resources:

Phases of the moon: 2001 to 2100

Solstices and equinoxes: 2001 to 2100

What most call a Blue Moon isn’t blue in color. It’s only Blue in name. This great moon photo is from EarthSky Facebook friend Rebecca Lacey in Cambridge, Idaho.

Bottom line: A blue-colored moon is rare. But folklore has defined two different kinds of Blue Moons, and moons that are Blue by name are pretty common. The next Blue Moon will come on October 31, 2020. It’ll be called a Blue Moon because it’ll be the second of two full moons in a single calendar month.

Possible to have only 2 full moons in a single season?

Enjoying EarthSky so far? Sign up for our free daily newsletter today!

from EarthSky https://ift.tt/3fYhcC8

Most Blue Moons are not blue in color. This photo of a moon among fast-moving clouds was created using special blue filters. Image via our friend Jv Noriega.

The next Blue Moon will come on October 31, 2020. It’ll be called a Blue Moon because it’ll be the second of two full moons to occur in a single calendar month. The last Blue Moon by this definition of the term happened on March 31, 2018.

There’s another definition for Blue Moon. It can be the third of four full moons in a single season, with a season being between a solstice and equinox. The next seasonal Blue Moon will be August 22, 2021.

In recent years, people have been using the name Blue Moon for these two different sorts of moons: second of two full moons in a calendar month, or third of four full moons in a single season.

Someday, you might see an actual blue-colored moon. Meanwhile, the moon you’ll see on October 31, 2020, likely won’t look blue, and blue-colored moons in photos – like the ones on this page – are usually made using special blue camera filters or in a post-processing program such as PhotoShop.

EarthSky 2020 lunar calendars are available! Nearly sold out. Order now!

The Virtual Telescope Project in Rome, Italy, hosted a live viewing of the May 18, 2019, full moon rising above the Rome skyline.

Let’s talk about seasonal Blue Moons first. A year has 12 months, and months – or “moonths” – have lengths more or less based on a single orbit of the moon around Earth. What we call a season – winter, spring, summer, fall – typically lasts three months, and typically has three full moons.

If a season has four full moons, then the third full moon may be called a Blue Moon, according to the old Maine Farmer’s Almanac. There was a Blue Moon by this definition on November 21, 2010, another on August 20-21, 2013, another on May 21, 2016, and another on May 18, 2019. The next will be on August 22, 2021.

Desert Blue Moon from our friend Priya Kumar in Oman, August 2012. Thank you, Priya!

The best-known and most popular definition of Blue Moon is that it describes the second full moon of a calendar month. By this definition, there was a Blue Moon on July 31, 2015, January 31, 2018, and March 31, 2018. The next one will be October 31, 2020.

The time between one full moon and the next is close to the length of a calendar month. So the only time one month can have two full moons is when the first full moon happens in the first few days of the month. This happens every two to three years, so these sorts of Blue Moons come about that often.

Very rarely, a seasonal Blue Moon (third of four full moons in one season) and a monthly Blue Moon (second of two full moons in one calendar month) can occur in the same calendar year. For this to happen, you need 13 full moons between successive December solstices for a seasonal Blue Moon – and, generally, 13 full moons in one calendar year for a monthly Blue Moon.

This will next happen in the year 2048, when a monthly Blue Moon falls on January 31, and a seasonal Blue Moon on August 23.

Then 19 years later, in the year 2067, there will be a monthly Blue Moon on March 30, and a seasonal Blue Moon on November 20. In this instance, there are 13 full moons between successive December solstices – but only 12 full moons in one calendar year and no February 2067 full moon.

Blue moons don’t really look blue in color. Greg Hogan got this shot of a Blue Moon (blue in name only!) on July 31, 2015. He wrote: “Having some fun with the blue moon idea……I blended the same image twice one with a blue tint, and one normal. :) “

The idea of a Blue Moon as the second full moon in a month stemmed from the March 1946 issue of Sky and Telescope magazine, which contained an article called Once in a Blue Moon by James Hugh Pruett. Pruett was referring to the 1937 Maine Farmer’s Almanac, but he inadvertently simplified the definition. He wrote:

Seven times in 19 years there were – and still are – 13 full moons in a year. This gives 11 months with one full moon each and one with two. This second in a month, so I interpret it, was called Blue Moon.

Had James Hugh Pruett looked at the actual date of the 1937 Blue Moon, he would have found that it had occurred August 21, 1937. Also, there were only 12 full moons in 1937. You generally need 13 full moons in one calendar year to have two full moons in one calendar month.

However, that fortuitous oversight gave birth to a new and perfectly understandable definition for Blue Moon.

EarthSky’s Deborah Byrd happened upon a copy of this old 1946 issue of Sky and Telescope in the stacks of the Peridier Library at the University of Texas Astronomy Department in the late 1970s. Afterward, she began using the term Blue Moon to describe the second full moon in a calendar month on the radio. Later, this definition of Blue Moon was also popularized by a book for children by Margot McLoon-Basta and Alice Siegel, called Kids’ World Almanac of Records and Facts, published in New York by World Almanac Publications in 1985. The second-full-moon-in-a-month definition was also used in the board game Trivial Pursuit.

Today, it has become part of folklore. As the folklorist Philip Hiscock wrote in his comprehensive article Once in a Blue Moon:

‘Old folklore’ it is not, but real folklore it is.

This photo was created using special blue filters, too. Image via EarthSky Facebook friend Jv Noriega.

Can a moon be blue in color? Yes, but it’s very rare to see a blue-colored moon. You need unusual sky conditions – certain-sized particles of dust or smoke – to create them.

Blue-colored moons aren’t predictable. So don’t be misled by the photos above. The sorts of moons people commonly call Blue Moons aren’t usually blue.

For more about truly blue-colored moons, click here.

Resources:

Phases of the moon: 2001 to 2100

Solstices and equinoxes: 2001 to 2100

What most call a Blue Moon isn’t blue in color. It’s only Blue in name. This great moon photo is from EarthSky Facebook friend Rebecca Lacey in Cambridge, Idaho.

Bottom line: A blue-colored moon is rare. But folklore has defined two different kinds of Blue Moons, and moons that are Blue by name are pretty common. The next Blue Moon will come on October 31, 2020. It’ll be called a Blue Moon because it’ll be the second of two full moons in a single calendar month.

Possible to have only 2 full moons in a single season?

Enjoying EarthSky so far? Sign up for our free daily newsletter today!

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Meet Corvus the Crow

A favorite constellation for many, little squarish Corvus the Crow, can be found after sunset at this time of year. It’s not far from Spica, the only bright star in the constellation Virgo. Once you find Spica, you’ll recognize Corvus easily. It’s always near the star Spica on the sky’s dome, recognizable for its compact, boxy shape. Spica is supposed to represent an Ear of Wheat, held by Virgo the Maiden. With a good imagination and a dark-enough sky, you can almost see Corvus as a real crow, pecking toward Spica, trying to snatch the wheat.

And thus the stories of the heavens were born …

You don’t need Corvus to identify the bright star Spica. You can use the Big Dipper for that as shown on the diagram below:

Use the handle of the Big Dipper to locate the stars Arcturus and Spica. Just follow the arc in the Dipper’s handle. And remember the phrase “follow the arc to Arcturus, and drive a spike to Spica.”

After you find Spica, Corvus is easy. It’s right next to the bright star, a small boxy pattern that’s noticeable to the eye. Because Corvus is such an easy and fun constellation to pick out in the sky, there are many legends in skylore about it. A lovely one comes from China, where this grouping of stars was seen as an imperial chariot, riding on the wind. In ancient Israel, and sometimes in Greek mythology, Corvus was said to be a raven, not a crow. The early Greeks saw Corvus as a cupbearer to Apollo, god of the sun. The website Constellation-guide.com explains that Corvus was:

… Apollo’s sacred bird in Greek mythology. According to the myth, the raven originally had white feathers. In one story, Apollo told the bird to watch over Coronis, one of his lovers, who was pregnant at the time.

Coronis gradually lost interest in Apollo and fell in love with a mortal man, Ischys. When the raven reported the affair to Apollo, the god was so enraged that the bird did nothing to stop it that he flung a curse on it, scorching the raven’s feathers. That, the legend goes, is why all ravens are black.

Corvus is a friendly sight in the heavens. Along with all the stars, Corvus’s stars will be found a bit farther west at nightfall in the coming weeks and months as Earth moves around the sun. Check it out now and watch for it in the next few months.

The bright star Spica – near Corvus on our sky’s dome – will always be there to guide your eye.

View at EarthSky Community Photos. | Dr Ski in Valencia, Philippines wrote: “Corvus (the Crow) and Crux (the Southern Cross) are at the same right ascension on the celestial sphere. Meaning, they transit the meridian at the same time (approximately 8:30 p.m. local time or 9:30 p.m. local daylight saving time). If you reside in mid-northern latitudes … look for the familiar polygon of Corvus at this time. Then extrapolate a line approximately 40° down to get an idea of how far below your horizon the Southern Cross is.” If you’re further south, of course, as Dr Ski is … just look!

Bottom line: Use the star Spica to introduce yourself to the constellation Corvus the Crow.

Enjoying EarthSky so far? Sign up for our free daily newsletter today!

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A favorite constellation for many, little squarish Corvus the Crow, can be found after sunset at this time of year. It’s not far from Spica, the only bright star in the constellation Virgo. Once you find Spica, you’ll recognize Corvus easily. It’s always near the star Spica on the sky’s dome, recognizable for its compact, boxy shape. Spica is supposed to represent an Ear of Wheat, held by Virgo the Maiden. With a good imagination and a dark-enough sky, you can almost see Corvus as a real crow, pecking toward Spica, trying to snatch the wheat.

And thus the stories of the heavens were born …

You don’t need Corvus to identify the bright star Spica. You can use the Big Dipper for that as shown on the diagram below:

Use the handle of the Big Dipper to locate the stars Arcturus and Spica. Just follow the arc in the Dipper’s handle. And remember the phrase “follow the arc to Arcturus, and drive a spike to Spica.”

After you find Spica, Corvus is easy. It’s right next to the bright star, a small boxy pattern that’s noticeable to the eye. Because Corvus is such an easy and fun constellation to pick out in the sky, there are many legends in skylore about it. A lovely one comes from China, where this grouping of stars was seen as an imperial chariot, riding on the wind. In ancient Israel, and sometimes in Greek mythology, Corvus was said to be a raven, not a crow. The early Greeks saw Corvus as a cupbearer to Apollo, god of the sun. The website Constellation-guide.com explains that Corvus was:

… Apollo’s sacred bird in Greek mythology. According to the myth, the raven originally had white feathers. In one story, Apollo told the bird to watch over Coronis, one of his lovers, who was pregnant at the time.

Coronis gradually lost interest in Apollo and fell in love with a mortal man, Ischys. When the raven reported the affair to Apollo, the god was so enraged that the bird did nothing to stop it that he flung a curse on it, scorching the raven’s feathers. That, the legend goes, is why all ravens are black.

Corvus is a friendly sight in the heavens. Along with all the stars, Corvus’s stars will be found a bit farther west at nightfall in the coming weeks and months as Earth moves around the sun. Check it out now and watch for it in the next few months.

The bright star Spica – near Corvus on our sky’s dome – will always be there to guide your eye.

View at EarthSky Community Photos. | Dr Ski in Valencia, Philippines wrote: “Corvus (the Crow) and Crux (the Southern Cross) are at the same right ascension on the celestial sphere. Meaning, they transit the meridian at the same time (approximately 8:30 p.m. local time or 9:30 p.m. local daylight saving time). If you reside in mid-northern latitudes … look for the familiar polygon of Corvus at this time. Then extrapolate a line approximately 40° down to get an idea of how far below your horizon the Southern Cross is.” If you’re further south, of course, as Dr Ski is … just look!

Bottom line: Use the star Spica to introduce yourself to the constellation Corvus the Crow.

Enjoying EarthSky so far? Sign up for our free daily newsletter today!

from EarthSky https://ift.tt/3g6dUgq

Will you see Comet SWAN?

View at EarthSky Community Photos. | Dr Ski in Valencia, Philippines (latitude 9 degrees north), caught this image of the comet on May 2, 2020, and wrote, “Comet C/2020 F8 (SWAN) was discovered in March by NASA’s SOHO imaging. At magnitude +5, it was easy to spot through binoculars in nautical twilight when this image was captured.” Thank you, Dr Ski! Has the comet continued to brighten? Not as much as hoped so far, but you never know. Read on …

Earlier this spring, bright Comet ATLAS was brightening steadily, on a course that might have brought it into visibility with the unaided eye. That was before it broke our hearts by fracturing into multiple pieces. Then, surprisingly, a second comet – recently discovered and initially visible only from Earth’s Southern Hemisphere – began brightening and creating a buzz among those who watch the skies. Comet C/2020 F8 (SWAN) is now visible with good binoculars in Northern Hemisphere skies, too, although finding it requires skill, with only a small window for locating it each day. That’s because the comet is rising only shortly before the sun, and can be found near the horizon when dawn breaks.

This comet has already come closest to Earth (on May 12-13, 2020), at a distance of 51.7 million miles (83.2 million km).

It’s now heading toward its perihelion, or closest point to the sun, on May 27, 2020.

Amateur astronomer Michael Mattiazzo in Australia discovered comet C/2020 F8 (SWAN) on April 11, 2020. Mattiazzo was not looking at the sky when he made his discovery. Instead, he saw the possible – and then confirmed – comet while reviewing images captured by the Solar Wind ANisotropies (SWAN) instrument aboard the Solar and Heliospheric Observatory (SOHO) spacecraft overseen by NASA and the European Space Agency. This is Mattiazzo’s 8th comet discovery; like comet C/2020 F8 (SWAN), his others were found via inspection of SOHO images. It is the SWAN instrument’s 12th comet discovery. And it’s SOHO’s 3,932nd comet discovery!

Read more: Here’s how SOHO and a skywatcher discovered Comet SWAN

Comet C/2020 F8 (SWAN) was ejecting huge amounts of water vapor, which showed as hydrogen on SOHO’s instrument, according to the European Space Agency. Michael Combi from the University of Michigan estimated that, by April 15, the comet was ejecting about 2,866 pounds (1,300 kg) of water vapor every second.

Thus, during the month of April, Comet SWAN showed a trend of increasing brightness – likely due to that temporary outburst in activity – but then that trend stopped. As of early and mid May, the comet is not getting brighter, although it might (or not) get somewhat brighter in the days during which it’s approaching the sun for its May 27 perihelium.

That previous apparent outburst was enough to let experienced observers at southerly latitudes view the comet without optical aid, barely, using peripheral or averted vision.

Some experienced astrophotographers have been able to capture amazing long-exposure images of Comet SWAN, some of which show that the comet’s tail is extremely long, as long as 20 times the apparent diameter of the full moon! Those observers were lucky to image Comet SWAN when it was high in the sky from their perspective. As stated above, though, this comet appears low in the sky as viewed in Northern Hemisphere skies. Its nearness to the horizon might subtract a little brightness of this (already not-so-bright) celestial visitor.

Check out the tweets below:

Always brilliant images from Fritz Helmut Hemmerich, and no different this time. Comet Swan from the Canary Islands on the 10th. pic.twitter.com/UJZFrKG4Xy

— Con Stoitsis (@vivstoitsis) May 10, 2020

The excited wagging of Comet SWAN's ion tail. Photos by Gerald Rhemann, taken over the first 5 days in May. https://t.co/sCvcXsGIdf pic.twitter.com/bf8D3yRwa1

— Corey S. Powell (@coreyspowell) May 9, 2020

Visible to the unaided eye? Probably not, but with comets, you never know.

Of course, the question on everyone’s mind is, will Comet SWAN become visible to the unaided eye? And the answer is, probably not.

It’s important to note that the photographs above are made by experienced photographers using telescopes and other special equipment. They do not mean that Comet SWAN is or was clearly visible to the unaided eye for most observers.

Observers at latitudes like those in the southern U.S. (say, 30 degrees north latitude) and locations in both hemispheres close to the equator have the best chance – still only a slight chance – to view or capture this horizon-grazing comet. Your location on the globe will be key here. Also, sky conditions for observing Comet SWAN are quite challenging. Observers equipped with binoculars or a small telescope will have a small window – only a few minutes, just before dawn – to spot it. Seeing it will, of course, also require a clear sky and, in that sense, the ongoing Covid-19 pandemic appears to have provided many parts of Earth with clearer skies, especially toward your horizons, than usual.

If you have a camera capable of taking long-exposure photos (which provide far more sensitivity than the human eye), a good option would be to point the camera at the approximate area where the comet is located (even if you don’t see the comet; charts provided below), and take several images at different exposures (30, 45, 60 seconds, or more), as well as diverse zoom settings. Then review those images, as some may reveal the comet with its greenish color, and perhaps even a hint of its long tail.

And, of course – as usual with comets – the unpredictability factor has to weigh in. We just don’t know what comets will do, until they do it.

One thing is certain. Sky enthusiasts will continue to monitor the comet using binoculars, small telescopes and cameras. Just don’t be fooled by claims that Comet SWAN will provide an “amazing and spectacular show” to the unaided eye. If you do see the comet with binoculars or a small telescope, your view – at best – might be more like this:

Comet SWAN has gotten a bit higher for my location in southwest Alabama. So here it is through trees!
SWAN revealed some of the tail. Image Richard Pickard. pic.twitter.com/hUHcDWoPqF

— Con Stoitsis (@vivstoitsis) May 13, 2020

You might catch it using binoculars or a small telescope, but with the caveat that it’s very, very close to the horizon, not to mention that it’s in our sky only shortly before dawn each day, as the comet approaches its closest point to the sun on May 27. Although any improvement in the comet’s visibility cannot be ruled out, it appears to be remaining just a binocular or camera target.

You’ll be looking toward your northeastern horizon, before sunup. See the charts at the bottom of this post.

Some charts to help you locate Comet SWAN in the sky

These charts are set for the latitude of the southern U.S. If you are elsewhere on the globe, the comet will be up at or around this same time of day, in front of these same constellations and near these same stars. But the comet, and the stars, will be oriented differently with respect to different horizons around the globe. Or they might not be above your horizon at all. Stellarium-Web is tracking Comet SWAN. Set your individual location on the globe, set the time for before dawn, face the program toward the northeast, and see the comet’s whereabouts each day.

May 17, 2020, just before dawn. Facing northeast, as seen from southern U.S. For an individualized view, try Stellarium. Illustration by Eddie Irizarry using Stellarium.

Location of Comet C/2020 F8 (SWAN) on May 19, 2020, shortly before dawn. Facing northeast, as seen from southern U.S. For an individualized view, try Stellarium. Illustration by Eddie Irizarry using Stellarium.

May 21, 2020, a few minutes before dawn. Facing northeast, as seen from southern U.S. For an individualized view, try Stellarium. Illustration by Eddie Irizarry using Stellarium.

By May 24, 2020, Comet SWAN will become increasingly closer to the horizon, making observations even more difficult, perhaps allowing only long-exposure photography. This chart faces northeast just before dawn, as seen from southern U.S. For an individualized view, try Stellarium. Illustration by Eddie Irizarry using Stellarium.

May 27, 2020. This is the date of the comet’s perihelion, or closest approach to the sun. At this point, Comet SWAN will be located extremely close to your sunrise horizon. This chart faces northeast just before dawn, as seen from southern U.S. For an individualized view, try Stellarium. Illustration by Eddie Irizarry using Stellarium.

May 31 – June 1, 2020. After passing close to the sun, Comet SWAN will reappear early in the evening sky, and pass close to star Capella. This chart faces northwest during evening dusk, as seen from southern U.S. For an individualized view, try Stellarium. Illustration by Eddie Irizarry using Stellarium.

Comet C/2020 F8 (SWAN). Image via Ezequiel Benitez, from Isabela, Puerto Rico.

Bottom line: Comet C/2020 F8 (SWAN) has provided experienced astrophotographers with some amazing captures. Now, for Northern Hemisphere observers, it appears very close to the northeastern horizon before sunup; we don’t expect this comet to be widely seen, or to become easily visible to the eye. It likely won’t be a great comet visually, but amateur astronomers will be keeping an eye on Comet SWAN, just in case.

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View at EarthSky Community Photos. | Dr Ski in Valencia, Philippines (latitude 9 degrees north), caught this image of the comet on May 2, 2020, and wrote, “Comet C/2020 F8 (SWAN) was discovered in March by NASA’s SOHO imaging. At magnitude +5, it was easy to spot through binoculars in nautical twilight when this image was captured.” Thank you, Dr Ski! Has the comet continued to brighten? Not as much as hoped so far, but you never know. Read on …

Earlier this spring, bright Comet ATLAS was brightening steadily, on a course that might have brought it into visibility with the unaided eye. That was before it broke our hearts by fracturing into multiple pieces. Then, surprisingly, a second comet – recently discovered and initially visible only from Earth’s Southern Hemisphere – began brightening and creating a buzz among those who watch the skies. Comet C/2020 F8 (SWAN) is now visible with good binoculars in Northern Hemisphere skies, too, although finding it requires skill, with only a small window for locating it each day. That’s because the comet is rising only shortly before the sun, and can be found near the horizon when dawn breaks.

This comet has already come closest to Earth (on May 12-13, 2020), at a distance of 51.7 million miles (83.2 million km).

It’s now heading toward its perihelion, or closest point to the sun, on May 27, 2020.

Amateur astronomer Michael Mattiazzo in Australia discovered comet C/2020 F8 (SWAN) on April 11, 2020. Mattiazzo was not looking at the sky when he made his discovery. Instead, he saw the possible – and then confirmed – comet while reviewing images captured by the Solar Wind ANisotropies (SWAN) instrument aboard the Solar and Heliospheric Observatory (SOHO) spacecraft overseen by NASA and the European Space Agency. This is Mattiazzo’s 8th comet discovery; like comet C/2020 F8 (SWAN), his others were found via inspection of SOHO images. It is the SWAN instrument’s 12th comet discovery. And it’s SOHO’s 3,932nd comet discovery!

Read more: Here’s how SOHO and a skywatcher discovered Comet SWAN

Comet C/2020 F8 (SWAN) was ejecting huge amounts of water vapor, which showed as hydrogen on SOHO’s instrument, according to the European Space Agency. Michael Combi from the University of Michigan estimated that, by April 15, the comet was ejecting about 2,866 pounds (1,300 kg) of water vapor every second.

Thus, during the month of April, Comet SWAN showed a trend of increasing brightness – likely due to that temporary outburst in activity – but then that trend stopped. As of early and mid May, the comet is not getting brighter, although it might (or not) get somewhat brighter in the days during which it’s approaching the sun for its May 27 perihelium.

That previous apparent outburst was enough to let experienced observers at southerly latitudes view the comet without optical aid, barely, using peripheral or averted vision.

Some experienced astrophotographers have been able to capture amazing long-exposure images of Comet SWAN, some of which show that the comet’s tail is extremely long, as long as 20 times the apparent diameter of the full moon! Those observers were lucky to image Comet SWAN when it was high in the sky from their perspective. As stated above, though, this comet appears low in the sky as viewed in Northern Hemisphere skies. Its nearness to the horizon might subtract a little brightness of this (already not-so-bright) celestial visitor.

Check out the tweets below:

Always brilliant images from Fritz Helmut Hemmerich, and no different this time. Comet Swan from the Canary Islands on the 10th. pic.twitter.com/UJZFrKG4Xy

— Con Stoitsis (@vivstoitsis) May 10, 2020

The excited wagging of Comet SWAN's ion tail. Photos by Gerald Rhemann, taken over the first 5 days in May. https://t.co/sCvcXsGIdf pic.twitter.com/bf8D3yRwa1

— Corey S. Powell (@coreyspowell) May 9, 2020

Visible to the unaided eye? Probably not, but with comets, you never know.

Of course, the question on everyone’s mind is, will Comet SWAN become visible to the unaided eye? And the answer is, probably not.

It’s important to note that the photographs above are made by experienced photographers using telescopes and other special equipment. They do not mean that Comet SWAN is or was clearly visible to the unaided eye for most observers.

Observers at latitudes like those in the southern U.S. (say, 30 degrees north latitude) and locations in both hemispheres close to the equator have the best chance – still only a slight chance – to view or capture this horizon-grazing comet. Your location on the globe will be key here. Also, sky conditions for observing Comet SWAN are quite challenging. Observers equipped with binoculars or a small telescope will have a small window – only a few minutes, just before dawn – to spot it. Seeing it will, of course, also require a clear sky and, in that sense, the ongoing Covid-19 pandemic appears to have provided many parts of Earth with clearer skies, especially toward your horizons, than usual.

If you have a camera capable of taking long-exposure photos (which provide far more sensitivity than the human eye), a good option would be to point the camera at the approximate area where the comet is located (even if you don’t see the comet; charts provided below), and take several images at different exposures (30, 45, 60 seconds, or more), as well as diverse zoom settings. Then review those images, as some may reveal the comet with its greenish color, and perhaps even a hint of its long tail.

And, of course – as usual with comets – the unpredictability factor has to weigh in. We just don’t know what comets will do, until they do it.

One thing is certain. Sky enthusiasts will continue to monitor the comet using binoculars, small telescopes and cameras. Just don’t be fooled by claims that Comet SWAN will provide an “amazing and spectacular show” to the unaided eye. If you do see the comet with binoculars or a small telescope, your view – at best – might be more like this:

Comet SWAN has gotten a bit higher for my location in southwest Alabama. So here it is through trees!
SWAN revealed some of the tail. Image Richard Pickard. pic.twitter.com/hUHcDWoPqF

— Con Stoitsis (@vivstoitsis) May 13, 2020

You might catch it using binoculars or a small telescope, but with the caveat that it’s very, very close to the horizon, not to mention that it’s in our sky only shortly before dawn each day, as the comet approaches its closest point to the sun on May 27. Although any improvement in the comet’s visibility cannot be ruled out, it appears to be remaining just a binocular or camera target.

You’ll be looking toward your northeastern horizon, before sunup. See the charts at the bottom of this post.

Some charts to help you locate Comet SWAN in the sky

These charts are set for the latitude of the southern U.S. If you are elsewhere on the globe, the comet will be up at or around this same time of day, in front of these same constellations and near these same stars. But the comet, and the stars, will be oriented differently with respect to different horizons around the globe. Or they might not be above your horizon at all. Stellarium-Web is tracking Comet SWAN. Set your individual location on the globe, set the time for before dawn, face the program toward the northeast, and see the comet’s whereabouts each day.

May 17, 2020, just before dawn. Facing northeast, as seen from southern U.S. For an individualized view, try Stellarium. Illustration by Eddie Irizarry using Stellarium.

Location of Comet C/2020 F8 (SWAN) on May 19, 2020, shortly before dawn. Facing northeast, as seen from southern U.S. For an individualized view, try Stellarium. Illustration by Eddie Irizarry using Stellarium.

May 21, 2020, a few minutes before dawn. Facing northeast, as seen from southern U.S. For an individualized view, try Stellarium. Illustration by Eddie Irizarry using Stellarium.

By May 24, 2020, Comet SWAN will become increasingly closer to the horizon, making observations even more difficult, perhaps allowing only long-exposure photography. This chart faces northeast just before dawn, as seen from southern U.S. For an individualized view, try Stellarium. Illustration by Eddie Irizarry using Stellarium.

May 27, 2020. This is the date of the comet’s perihelion, or closest approach to the sun. At this point, Comet SWAN will be located extremely close to your sunrise horizon. This chart faces northeast just before dawn, as seen from southern U.S. For an individualized view, try Stellarium. Illustration by Eddie Irizarry using Stellarium.

May 31 – June 1, 2020. After passing close to the sun, Comet SWAN will reappear early in the evening sky, and pass close to star Capella. This chart faces northwest during evening dusk, as seen from southern U.S. For an individualized view, try Stellarium. Illustration by Eddie Irizarry using Stellarium.

Comet C/2020 F8 (SWAN). Image via Ezequiel Benitez, from Isabela, Puerto Rico.

Bottom line: Comet C/2020 F8 (SWAN) has provided experienced astrophotographers with some amazing captures. Now, for Northern Hemisphere observers, it appears very close to the northeastern horizon before sunup; we don’t expect this comet to be widely seen, or to become easily visible to the eye. It likely won’t be a great comet visually, but amateur astronomers will be keeping an eye on Comet SWAN, just in case.

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2 views from space: San Francisco Bay

View larger. | In the larger view, you can see Golden Gate Bridge, 1.7 miles long (2.7 km long). It’s visible crossing the opening of the bay into the Pacific Ocean between Marin County and the city of San Francisco (at the tip of the southern peninsula in the center of the image). Image via ESA.

We thought many of you would enjoy these two images from space of one of Earth’s most captivating places: San Francisco Bay.

The European Space Agency (ESA) shared the image above on May 15, 2020. It’s a view of San Francisco Bay from the Copernicus Sentinel-2 mission, which consists of twin Earth-observing satellites, launched in 2015. They routinely acquire beautiful optical imagery of Earth; see more here. In describing the image above, ESA wrote that San Francisco Bay is:

… almost 100 km [60 miles] in length – a shallow estuary surrounded by the San Francisco Bay Area – an extensive metropolitan region that is dominated by large cities such as San Francisco, Oakland and San Jose. The densely populated urban areas around the bay contrast strongly with the surrounding green forest and park areas.

In the upper right of the image, the delta of the Sacramento and San Joaquin rivers is visible – with the brown, sediment-filled water flowing down into San Pablo Bay. Here, the murky waters mix before flowing into the larger bay area, which is connected to the Pacific Ocean via the Golden Gate strait. A large sediment plume can be seen traveling westward into the Pacific in the left of the image.

The Golden Gate Bridge, around 2.7 km long [1.7 miles], is visible crossing the opening of the bay into the Pacific Ocean between Marin County and the city of San Francisco – which can be seen at the tip of the southern peninsula in the center of the image. Treasure, Angel and Alcatraz islands can be seen sticking out of the waters of the bay, with several bridges connecting its east and west shores. Several boats are also visible …

Read more about this image from ESA.

Since some of its earliest missions, astronauts traveling aboard the International Space Station (ISS) have also been tempted to capture the beauty of San Francisco Bay. The image below is from ISS Expedition 4 (December 2001 to June 2002; the current mission is Expedition 63). NASA wrote of the image below:

This view featuring the San Francisco Bay Area was photographed by an Expedition 4 crewmember onboard the International Space Station. The gray urban footprint of San Francisco, Oakland, San Jose, and their surrounding suburbs contrasts strongly with the green hillsides. Pacific Ocean water patterns are highlighted in the sun glint. Sets of internal waves traveling east impinge on the coastline south of San Francisco. At the same time, fresher bay water flows out from the bay beneath the Golden Gate Bridge, creating a large plume traveling westward. Tidal current channels suggest the tidal flow deep in the bay.

View larger. | San Francisco Bay via Expedition 4 of the International Space Station (December 2001 to June 2002). Image via NASA.

Bottom line: A beautiful image of San Francisco Bay via ESA’s Copernicus Sentinel-2 mission.

from EarthSky https://ift.tt/2T8znew

View larger. | In the larger view, you can see Golden Gate Bridge, 1.7 miles long (2.7 km long). It’s visible crossing the opening of the bay into the Pacific Ocean between Marin County and the city of San Francisco (at the tip of the southern peninsula in the center of the image). Image via ESA.

We thought many of you would enjoy these two images from space of one of Earth’s most captivating places: San Francisco Bay.

The European Space Agency (ESA) shared the image above on May 15, 2020. It’s a view of San Francisco Bay from the Copernicus Sentinel-2 mission, which consists of twin Earth-observing satellites, launched in 2015. They routinely acquire beautiful optical imagery of Earth; see more here. In describing the image above, ESA wrote that San Francisco Bay is:

… almost 100 km [60 miles] in length – a shallow estuary surrounded by the San Francisco Bay Area – an extensive metropolitan region that is dominated by large cities such as San Francisco, Oakland and San Jose. The densely populated urban areas around the bay contrast strongly with the surrounding green forest and park areas.

In the upper right of the image, the delta of the Sacramento and San Joaquin rivers is visible – with the brown, sediment-filled water flowing down into San Pablo Bay. Here, the murky waters mix before flowing into the larger bay area, which is connected to the Pacific Ocean via the Golden Gate strait. A large sediment plume can be seen traveling westward into the Pacific in the left of the image.

The Golden Gate Bridge, around 2.7 km long [1.7 miles], is visible crossing the opening of the bay into the Pacific Ocean between Marin County and the city of San Francisco – which can be seen at the tip of the southern peninsula in the center of the image. Treasure, Angel and Alcatraz islands can be seen sticking out of the waters of the bay, with several bridges connecting its east and west shores. Several boats are also visible …

Read more about this image from ESA.

Since some of its earliest missions, astronauts traveling aboard the International Space Station (ISS) have also been tempted to capture the beauty of San Francisco Bay. The image below is from ISS Expedition 4 (December 2001 to June 2002; the current mission is Expedition 63). NASA wrote of the image below:

This view featuring the San Francisco Bay Area was photographed by an Expedition 4 crewmember onboard the International Space Station. The gray urban footprint of San Francisco, Oakland, San Jose, and their surrounding suburbs contrasts strongly with the green hillsides. Pacific Ocean water patterns are highlighted in the sun glint. Sets of internal waves traveling east impinge on the coastline south of San Francisco. At the same time, fresher bay water flows out from the bay beneath the Golden Gate Bridge, creating a large plume traveling westward. Tidal current channels suggest the tidal flow deep in the bay.

View larger. | San Francisco Bay via Expedition 4 of the International Space Station (December 2001 to June 2002). Image via NASA.

Bottom line: A beautiful image of San Francisco Bay via ESA’s Copernicus Sentinel-2 mission.

from EarthSky https://ift.tt/2T8znew

News digest – 15-minute prostate test, COVID-19 AI database, CAR T cell therapy and cancer ancestry links

Test for prostate cancer ‘in under 15 minutes’ 

A new ‘prostogram’ test has been developed in the UK, which uses MRI to detect cancer. Science Focus covered early results from a trial involving 400 men aged 50–69 suggest the scan was better at detecting aggressive cancers than the current test. It’s hoped that the new, non-invasive testing method will encourage more men to get checked for prostate cancer. The 15 minute scan is not the only way MRI is being used to help improve prostate cancer diagnosis, as our blog post explains.  

Cancer drug database adapted for COVID-19  

CanSar, a powerful database used to collate cancer research and drug discovery, is being adapted by a team at The Institute of Cancer Research to help accelerate the search for COVID-19 treatments. The new knowledgebase, Coronavirus-CanSar, will draw on worldwide data for COVID-19 and related diseases such as SARS and MERS. By creating a one-stop resource, the hope is researchers may be able to rapidly repurpose drugs to combat the disease. Engineering and Technology and our blog post have the full story.  

Study suggest more people with lymphoma could benefit from CAR T cell therapy 

News Medical reports that immune-boosting CAR T cell therapy has the potential to treat a wider group of patients with lymphoma than trials suggested. In a study involving 298 people who were treated in hospitals across the US, the treatment was shown to be tolerated by patients who wouldn’t have been eligible for the treatment in the original trials because of their comorbidities. 

And finally… 

Scientists at the NCI Cancer Genome Analysis Network in the US have been researching the connection between ancestry and the molecular makeup of cancers. By studying databases including over 10,500 patients and 33 cancer types, the group concluded that ancestry is linked to variations in hundreds of genes, but most were specific to a particular cancer type. Find out more at Cosmos.

Scarlett Sangster is a writer for PA Media Group

from Cancer Research UK – Science blog https://ift.tt/364RCqB

Test for prostate cancer ‘in under 15 minutes’ 

A new ‘prostogram’ test has been developed in the UK, which uses MRI to detect cancer. Science Focus covered early results from a trial involving 400 men aged 50–69 suggest the scan was better at detecting aggressive cancers than the current test. It’s hoped that the new, non-invasive testing method will encourage more men to get checked for prostate cancer. The 15 minute scan is not the only way MRI is being used to help improve prostate cancer diagnosis, as our blog post explains.  

Cancer drug database adapted for COVID-19  

CanSar, a powerful database used to collate cancer research and drug discovery, is being adapted by a team at The Institute of Cancer Research to help accelerate the search for COVID-19 treatments. The new knowledgebase, Coronavirus-CanSar, will draw on worldwide data for COVID-19 and related diseases such as SARS and MERS. By creating a one-stop resource, the hope is researchers may be able to rapidly repurpose drugs to combat the disease. Engineering and Technology and our blog post have the full story.  

Study suggest more people with lymphoma could benefit from CAR T cell therapy 

News Medical reports that immune-boosting CAR T cell therapy has the potential to treat a wider group of patients with lymphoma than trials suggested. In a study involving 298 people who were treated in hospitals across the US, the treatment was shown to be tolerated by patients who wouldn’t have been eligible for the treatment in the original trials because of their comorbidities. 

And finally… 

Scientists at the NCI Cancer Genome Analysis Network in the US have been researching the connection between ancestry and the molecular makeup of cancers. By studying databases including over 10,500 patients and 33 cancer types, the group concluded that ancestry is linked to variations in hundreds of genes, but most were specific to a particular cancer type. Find out more at Cosmos.

Scarlett Sangster is a writer for PA Media Group

from Cancer Research UK – Science blog https://ift.tt/364RCqB

Bright star Vega on May evenings

Vega is a lovely star to come to know. When I was first learning the night sky, more than 40 years ago, I spent hours, days, weeks, months poring over charts and books. So I sometimes came to know the names and whereabouts of certain stars before seeing them in the night sky. One soft May evening, I happened to glance toward the northeast. I was thrilled at the sight of Vega – gleaming sapphire-blue – and surprisingly bright for being so low in the sky.

Look for this star tonight. It’s the fifth brightest star in our sky. If you’re in the Northern Hemisphere, you’ll find beautiful, bluish Vega easily, simply by looking northeastward at mid-evening in May. Vega is so bright that you can see it on a moonlit night.

From far south in the Southern Hemisphere, you can’t see Vega until late at night in May. That’s because Vega is located so far north on the sky’s dome. Vega will reach its high point for the night around three to four hours after midnight, at which time people in the Southern Hemisphere can see this star in their northern sky. As seen from mid-northern latitudes, the star shines high overhead at this early morning hour.

Because it’s the brightest star in the constellation Lyra the Harp, Vega is sometimes called the Harp Star. Like all stars, Vega rises some four minutes earlier each day as Earth moves around the sun. So Vega will ornament our evening sky throughout the summer and fall.

Although Vega is considered a late spring or summer star, it’s actually so far north on the sky’s dome that – from mid-latitudes in the Northern Hemisphere – you can find it at some time during the night, nearly every night of the year.

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View at EarthSky Community Photos. | Here’s Vega as seen around 3 a.m. from Valencia, Philippines, on May 10, 2019, from our friend Dr Ski. See Vega’s beautiful blue color? Notice the star near Vega, marked the Greek letter Epsilon. This star is Epsilon Lyrae, a famous double-double star.

Bottom line: It’s easy to identify the star Vega in the constellation Lyra at this time of year. From the Northern Hemisphere, look northeast in the evening for a bright, bluish star above the northeastern horizon.

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

from EarthSky https://ift.tt/3bEdY3r

Vega is a lovely star to come to know. When I was first learning the night sky, more than 40 years ago, I spent hours, days, weeks, months poring over charts and books. So I sometimes came to know the names and whereabouts of certain stars before seeing them in the night sky. One soft May evening, I happened to glance toward the northeast. I was thrilled at the sight of Vega – gleaming sapphire-blue – and surprisingly bright for being so low in the sky.

Look for this star tonight. It’s the fifth brightest star in our sky. If you’re in the Northern Hemisphere, you’ll find beautiful, bluish Vega easily, simply by looking northeastward at mid-evening in May. Vega is so bright that you can see it on a moonlit night.

From far south in the Southern Hemisphere, you can’t see Vega until late at night in May. That’s because Vega is located so far north on the sky’s dome. Vega will reach its high point for the night around three to four hours after midnight, at which time people in the Southern Hemisphere can see this star in their northern sky. As seen from mid-northern latitudes, the star shines high overhead at this early morning hour.

Because it’s the brightest star in the constellation Lyra the Harp, Vega is sometimes called the Harp Star. Like all stars, Vega rises some four minutes earlier each day as Earth moves around the sun. So Vega will ornament our evening sky throughout the summer and fall.

Although Vega is considered a late spring or summer star, it’s actually so far north on the sky’s dome that – from mid-latitudes in the Northern Hemisphere – you can find it at some time during the night, nearly every night of the year.

Enjoying EarthSky so far? Sign up for our free daily newsletter today!

View at EarthSky Community Photos. | Here’s Vega as seen around 3 a.m. from Valencia, Philippines, on May 10, 2019, from our friend Dr Ski. See Vega’s beautiful blue color? Notice the star near Vega, marked the Greek letter Epsilon. This star is Epsilon Lyrae, a famous double-double star.

Bottom line: It’s easy to identify the star Vega in the constellation Lyra at this time of year. From the Northern Hemisphere, look northeast in the evening for a bright, bluish star above the northeastern horizon.

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

from EarthSky https://ift.tt/3bEdY3r

Vega: Brilliant blue-white star in the Summer Triangle

The blue-white star Vega via Fred Espenak. Used with permission.

The beautiful blue-white star Vega has a special place in the hearts of skywatchers around the world. Come to know it, and you will see.

How to see Vega. Observers in the Northern Hemisphere typically begin noticing Vega in the evening around May, when this star comes into view in the northeast in mid-evening. You can see Vega in very early evening by June – and high in the east by August evenings – high overhead on autumn evenings – in the northwestern quadrant of the sky on December evenings.

Vega is easily recognizable for its brilliance and blue-white color. You can also easily pick out its constellation Lyra, which is small and compact, and consists primarily of Vega and four fainter stars in the form of a parallelogram.

The little constellation Lyra has some interesting features. Near Vega is Epsilon Lyrae, the famed “double-double” star. Between the Gamma and Beta stars is the famous Ring Nebula, visible in small telescopes.

Vega is one of three stars in an asterism – or noticeable star pattern – called the Summer Triangle in the early evening sky. The other two stars in the Triangle are Deneb and Altair. You can see the Summer Triangle in the evening beginning around June, through the end of each year.

The constellation Lyra the Harp and its brightest star Vega.

Vega in history and myth. In western skylore, Vega’s constellation Lyra is said to be the harp played by the legendary Greek musician Orpheus. It’s said that when Orpheus played this harp, neither god nor mortal could turn away.

In western culture, Vega is often called the Harp Star.

Star-crossed lovers Zhinu – represented by the star Vega in the constellation Lyra – and a humble farm boy, Niulang, represented by the star Altair in Aquila. Image via The NewsTalkers.

Here are the stars depicted in the illustration above, from Matthew Chin in Yuen Long, Hong Kong.

But the most beautiful story relating to Vega comes from Asia. There are many variations. In China, the legend speaks of a forbidden romance between the goddess Zhinu – represented by Vega – and a humble farm boy, Niulang – represented by the star Altair. Separated in the night sky by the Milky Way, or Celestial River, the two lovers are allowed to meet only once a year. It’s said that meeting comes on the 7th night of the 7th moon, when a bridge of magpies forms across the Celestial River, and the two lovers are reunited.

Their reunion marks the time of the Qixi Festival.

In Japan, the festival is called Tanabata. Orihime and her lover Hikoboshi meet on a bridge of magpies across the Celestial River, each year on the 7th night of the 7th moon. Image via Anhellica/Lilliacerise’s blog.

In Japan, Vega is called Orihime, a celestial princess or goddess. She falls in love with a mortal, Hikoboshi, represented by the star Altair. But when Orihime’s father finds out, he is enraged and forbids her to see this mere mortal. Then … you know the story. The two lovers are placed in the sky, separated by the Celestial River or Milky Way. Yet the sky gods are kind, and they reunite on the 7th night of the 7th moon each year. Sometimes Hikoboshi’s annual trip across the Celestial River is treacherous, though, and he doesn’t make it. In that case, Orihime’s tears form raindrops that fall over Japan.

Many Japanese celebrations of Tanabata are held in July, but sometimes they are held in August. If it rains, the raindrops are thought to be Orihime’s tears because Hikoboshi could not meet her. Sometimes, the Perseid meteor shower is said to represent Orihime’s tears.

Vega science. Vega is the 5th brightest star visible from Earth, and the 3rd brightest easily visible from mid-northern latitudes, after Sirius and Arcturus. At about 25 light-years in distance, it is the 6th closest of all the bright stars, or 5th if you exclude Alpha Centauri, which is not easily visible from most of the Northern Hemisphere.

Size of the star Vega in contrast to our sun. Image via RJHall/ Wikimedia Commons

Vega’s distinctly blue color indicates a surface temperature of nearly 17,000 degrees Fahrenheit (9,400 Celsius), making it about 7,000 degrees F (4,000 C) hotter than our sun. Roughly 2.5 times the diameter of the sun, and just less than that in mass, Vega’s internal pressures and temperatures are far greater than our sun, making it burn its fuel faster. This causes Vega to produce 35 to 40 times the energy of the sun, which in turn shortens its lifetime. At about 500 million years, Vega is already middle-aged. Currently it is only about a tenth the age of our sun, and will run out of fuel in another half-billion years.

In astronomer-speak, Vega is an “A0V main sequence star.” The “A0” signifies its temperature, whereas the “V” is a measure of energy output (luminosity), indicating that Vega is a normal star (not a giant). “Main sequence” again testifies to the fact that it belongs in the category of normal stars, and that it produces energy through stable fusion of hydrogen into helium. With a visual magnitude (apparent brightness) of 0.03, Vega is only marginally dimmer than Arcturus, but with a distinctly different, cool-blue color.

Vega’s position is RA: 18h 36m 56.3s, dec: +38° 47′ 1.3″.

Bottom line: The star Vega in the constellation Lyra is one of the sky’s most beloved stars, for people around the world.

from EarthSky https://ift.tt/362gwY1

The blue-white star Vega via Fred Espenak. Used with permission.

The beautiful blue-white star Vega has a special place in the hearts of skywatchers around the world. Come to know it, and you will see.

How to see Vega. Observers in the Northern Hemisphere typically begin noticing Vega in the evening around May, when this star comes into view in the northeast in mid-evening. You can see Vega in very early evening by June – and high in the east by August evenings – high overhead on autumn evenings – in the northwestern quadrant of the sky on December evenings.

Vega is easily recognizable for its brilliance and blue-white color. You can also easily pick out its constellation Lyra, which is small and compact, and consists primarily of Vega and four fainter stars in the form of a parallelogram.

The little constellation Lyra has some interesting features. Near Vega is Epsilon Lyrae, the famed “double-double” star. Between the Gamma and Beta stars is the famous Ring Nebula, visible in small telescopes.

Vega is one of three stars in an asterism – or noticeable star pattern – called the Summer Triangle in the early evening sky. The other two stars in the Triangle are Deneb and Altair. You can see the Summer Triangle in the evening beginning around June, through the end of each year.

The constellation Lyra the Harp and its brightest star Vega.

Vega in history and myth. In western skylore, Vega’s constellation Lyra is said to be the harp played by the legendary Greek musician Orpheus. It’s said that when Orpheus played this harp, neither god nor mortal could turn away.

In western culture, Vega is often called the Harp Star.

Star-crossed lovers Zhinu – represented by the star Vega in the constellation Lyra – and a humble farm boy, Niulang, represented by the star Altair in Aquila. Image via The NewsTalkers.

Here are the stars depicted in the illustration above, from Matthew Chin in Yuen Long, Hong Kong.

But the most beautiful story relating to Vega comes from Asia. There are many variations. In China, the legend speaks of a forbidden romance between the goddess Zhinu – represented by Vega – and a humble farm boy, Niulang – represented by the star Altair. Separated in the night sky by the Milky Way, or Celestial River, the two lovers are allowed to meet only once a year. It’s said that meeting comes on the 7th night of the 7th moon, when a bridge of magpies forms across the Celestial River, and the two lovers are reunited.

Their reunion marks the time of the Qixi Festival.

In Japan, the festival is called Tanabata. Orihime and her lover Hikoboshi meet on a bridge of magpies across the Celestial River, each year on the 7th night of the 7th moon. Image via Anhellica/Lilliacerise’s blog.

In Japan, Vega is called Orihime, a celestial princess or goddess. She falls in love with a mortal, Hikoboshi, represented by the star Altair. But when Orihime’s father finds out, he is enraged and forbids her to see this mere mortal. Then … you know the story. The two lovers are placed in the sky, separated by the Celestial River or Milky Way. Yet the sky gods are kind, and they reunite on the 7th night of the 7th moon each year. Sometimes Hikoboshi’s annual trip across the Celestial River is treacherous, though, and he doesn’t make it. In that case, Orihime’s tears form raindrops that fall over Japan.

Many Japanese celebrations of Tanabata are held in July, but sometimes they are held in August. If it rains, the raindrops are thought to be Orihime’s tears because Hikoboshi could not meet her. Sometimes, the Perseid meteor shower is said to represent Orihime’s tears.

Vega science. Vega is the 5th brightest star visible from Earth, and the 3rd brightest easily visible from mid-northern latitudes, after Sirius and Arcturus. At about 25 light-years in distance, it is the 6th closest of all the bright stars, or 5th if you exclude Alpha Centauri, which is not easily visible from most of the Northern Hemisphere.

Size of the star Vega in contrast to our sun. Image via RJHall/ Wikimedia Commons

Vega’s distinctly blue color indicates a surface temperature of nearly 17,000 degrees Fahrenheit (9,400 Celsius), making it about 7,000 degrees F (4,000 C) hotter than our sun. Roughly 2.5 times the diameter of the sun, and just less than that in mass, Vega’s internal pressures and temperatures are far greater than our sun, making it burn its fuel faster. This causes Vega to produce 35 to 40 times the energy of the sun, which in turn shortens its lifetime. At about 500 million years, Vega is already middle-aged. Currently it is only about a tenth the age of our sun, and will run out of fuel in another half-billion years.

In astronomer-speak, Vega is an “A0V main sequence star.” The “A0” signifies its temperature, whereas the “V” is a measure of energy output (luminosity), indicating that Vega is a normal star (not a giant). “Main sequence” again testifies to the fact that it belongs in the category of normal stars, and that it produces energy through stable fusion of hydrogen into helium. With a visual magnitude (apparent brightness) of 0.03, Vega is only marginally dimmer than Arcturus, but with a distinctly different, cool-blue color.

Vega’s position is RA: 18h 36m 56.3s, dec: +38° 47′ 1.3″.

Bottom line: The star Vega in the constellation Lyra is one of the sky’s most beloved stars, for people around the world.

from EarthSky https://ift.tt/362gwY1