Annular solar eclipse on December 26

Above: An annular solar eclipse – now often called a ring of fire eclipse – caught by Geoff Sims on May 10, 2013. The “fire” is really the sun’s brilliant surface, shining behind the moon in the far part of its orbit around Earth.

2019’s only annular eclipse – the third and final solar eclipse of this year – falls on December 26. It’s visible along a narrow path in the world’s Eastern Hemisphere. Like a total solar eclipse, an annular solar eclipse happens when the new moon moves directly in front of the sun. During a total solar eclipse, the new moon completely covers over the solar disk. During an annular eclipse, the lunar disk is too small to totally cover over the sun, so an annulus – or thin ring of the sun’s surface – surrounds the new moon silhouette.

The first solar eclipse on January 6, 2019, was a partial solar eclipse, and the second one on July 2, 2019, was a total solar eclipse. Because this is an annular eclipse – not a total solar eclipse – there is no safe window for directly watching this eclipse without proper eye protection.

Observing solar eclipses safely

The above diagram shows a total solar eclipse (A), annular eclipse (B) and partial solar eclipse (C). Image via Wikimedia Commons.

We refer you to the map (and animation) of the December 26th annular eclipse below. The narrow red ribbon outlines the narrow path of the annular eclipse, starting at sunrise in Saudi Arabia (at left) and then ending at sunset over the North Pacific Ocean (at right). It takes the moon’s antumbral shadow some 3 1/3 hours to traverse this 8,000 mile (12,900 km) annular eclipse path, which has a width varying from 73 miles (117 km) wide at the path’s center to 100 miles (over 160 km) wide at the path’s beginning and ending points.

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

The narrow annular eclipse path (in red) starts at sunrise at left ,over Saudi Arabia. and ends at sunset at right over the North Pacific ocean. The annular eclipse takes 3 1/3 hours to traverse this 8,000 mile (12,900 km) path. At any one point on the path, however, the maximum duration of the annular eclipse is only 3 2/3 minutes. Visit EclipseWise.com for an extended version of the above map, or see TimeAndDate.com for a detailed map and local eclipse times.

Animated version of the above map. The small dot depicts the path of the annular eclipse, whereas the much larger circle surrounding the small dot shows the viewing area for a partial solar eclipse.

The annular eclipse is visible from some parts of Saudi Arabia, Qatar, United Arab Emirates, Oman, India, Sri Lanka, Malaysia, Indonesia, Singapore, Northern Mariana Islands, and Guam. Outside the long and narrow road of the annular eclipse, a much broader swath of the world can watch varying degrees of a partial eclipse. The farther north or south you are from the annular eclipse path, the shallower the partial solar eclipse in your sky. The numbers on the map (0.80, 0.60, 0.40, 0.20) tell you the eclipse magnitude – the portion of the sun’s diameter that is covered over by the moon. To find out if and when this eclipse comes to your part of the world, try the wonderful resources below, which give the eclipse times in local time (no conversion from Universal Time to local time is necessary):

Eclipse map and local eclipse times via TimeandDate

Local eclipse times for numerous cities via EclipseWise

If you live along the annular eclipse path, be mindful that a partial eclipse precedes and follows the short-lived annular eclipse. We give the eclipse times for some cities along the path of annularity in local time (no conversion necessary):

Hofuf, Saudi Arabia
Sunrise (partial eclipse in progress): 6:25 a.m. local time (December 26)
Annular eclipse begins: 6:34:39 a.m. (December 26)
Maximum eclipse: 6:36:06 a.m. (December 26)
Annular eclipse ends: 6:37 a.m. (December 26)
Partial eclipse ends: 7:48:34 a.m.(December 26)

Kannur, India
Partial eclipse begins: 8:04:56 a.m. local time (December 26)
Annular eclipse begins: 9:24:53 a.m. (December 26)
Maximum eclipse: 9:26:20 a.m. (December 26)
Annular eclipse ends: 9:27:47 a.m. (December 26)
Partial eclipse ends: 11:05:34 a.m.(December 26)

Jaffna, Sri Lanka
Partial eclipse begins: 8:09:03 a.m. local time (December 26)
Annular eclipse begins: 9:33:57 a.m. (December 26)
Maximum eclipse: 9:35:30 a.m. (December 26)
Annular eclipse ends: 9:37:09 a.m. (December 26)
Partial eclipse ends: 11:21:14 a.m.(December 26)

Singapore, Singapore
Partial eclipse begins: 11:27:09 a.m. local time (December 26)
Annular eclipse begins: 1:22:43 p.m. (December 26)
Maximum eclipse: 1:24:42 p.m. (December 26)
Annular eclipse ends: 1:24:41 p.m. (December 26)
Partial eclipse ends: 3:18:26 p.m.(December 26)

Sri Aman, Malaysia
Partial eclipse begins: 11:52:11 a.m. local time (December 26)
Annular eclipse begins: 1:49:44 p.m. (December 26)
Maximum eclipse: 1:51:26 p.m. (December 26)
Annular eclipse ends: 1:53:07 p.m. (December 26)
Partial eclipse ends: 3:36:42 p.m.(December 26)

Sarangani Island, Philippines
Partial eclipse begins: 12:44:06 p.m. local time (December 26)
Annular eclipse begins: 2:29:43 p.m. (December 26)
Maximum eclipse: 2:30:53 p.m. (December 26)
Annular eclipse ends: 2:32:08 p.m. (December 26)
Partial eclipse ends: 3:57:22 p.m.(December 26)

Source: TimeandDate

Dates for the moon’s phases in 2019 via Astropixels. P = partial solar eclipse, T = total solar eclipse, and A = annular eclipse.

Six lunar months (six new moons) before this December 26th annular eclipse, there was a total eclipse of the sun on July 2, 2019. Back then, the new moon was some 10,000 miles (16,000 km) closer than the new moon of December 2019. Moreover, the sun in early July is about 3 million miles (5 million km) farther away than it is in late December. That all adds up to a total solar eclipse on July 2 (maximum duration: 4 minutes and 33 seconds), yet an annular eclipse on December 26 (maximum duration: 3 minutes and 40 seconds).

The longest lasting total solar solar eclipses happen when the moon is near perigee (closest point to Earth in its monthly orbit) and the Earth is near aphelion (farthest point from the sun). The longest total solar eclipse of the 21st century (2001 to 2100) took place on July 22, 2009, with a duration of 6 minutes and 39 seconds.

Annular eclipse of January 15, 2010, as seen in Bangui, Central African Republic, at 05:19:14 UTC (6:19 local time) via Tino Kreutzer.

On the other hand, the longest lasting annular eclipses happen when the moon is near apogee (its farthest point from Earth in its monthly orbit) and the Earth is near perihelion (closest point to the sun). The longest annular eclipse of the 21st century happened on January 15, 2010, or exactly 6 lunar months (6 new moons) after the century’s longest total solar eclipse on July 22, 2009. The annular eclipse of January 15, 2010, had a duration of 11 minutes and 8 seconds.

If we extend the period to 10,000 years (4,000 B.C. to 6,000 A.D.), rather than just one century, we find the longest total solar eclipse occurring on July 16, 2186 (7 minutes and 29 seconds) and the longest annular eclipse on December 7, 150 (12 minutes and 24 seconds).

Read more: Middle of eclipse season December 30

Correction: We mistakenly said in an earlier version of this article that – for an annular solar eclipse to occur – the new moon has to be near apogee, the farthest point in its orbit around Earth. The mistake was made in editing. As Bruce later pointed out, it’s true sometimes that – during an annular eclipse – the moon is near apogee. But that isn’t the case for the December 26 eclipse. In fact, the December new moon is almost exactly at its mean distance from Earth. Yet – at mid-eclipse – the moon is too small to cover the sun’s disk completely. Why? The answer is that – at this time of year – Earth is close to perihelion, its closest point to the sun for the year. In 2020, Earth’s perihelion will come on January 5 at 07:48 UTC (at 1:48 a.m. CST). So, in our sky around now, the sun’s disk appears slightly larger than usual: hence, the December 26, 2019 annular solar eclipse. Cool, yes? Now consider this: the longest-lasting annular eclipses do occur when the moon is near apogee and the Earth is near perihelion. The annular eclipse on December 26 is not a particularly long-lasting annular eclipse.

Bottom line: The 3rd and final solar eclipse of the year falls on December 26. It’s 2019’s only annular or “ring” eclipse. At mid-eclipse, a ring of the sun’s surface will appear around the moon.

from EarthSky https://ift.tt/39c1QGY

Above: An annular solar eclipse – now often called a ring of fire eclipse – caught by Geoff Sims on May 10, 2013. The “fire” is really the sun’s brilliant surface, shining behind the moon in the far part of its orbit around Earth.

2019’s only annular eclipse – the third and final solar eclipse of this year – falls on December 26. It’s visible along a narrow path in the world’s Eastern Hemisphere. Like a total solar eclipse, an annular solar eclipse happens when the new moon moves directly in front of the sun. During a total solar eclipse, the new moon completely covers over the solar disk. During an annular eclipse, the lunar disk is too small to totally cover over the sun, so an annulus – or thin ring of the sun’s surface – surrounds the new moon silhouette.

The first solar eclipse on January 6, 2019, was a partial solar eclipse, and the second one on July 2, 2019, was a total solar eclipse. Because this is an annular eclipse – not a total solar eclipse – there is no safe window for directly watching this eclipse without proper eye protection.

Observing solar eclipses safely

The above diagram shows a total solar eclipse (A), annular eclipse (B) and partial solar eclipse (C). Image via Wikimedia Commons.

We refer you to the map (and animation) of the December 26th annular eclipse below. The narrow red ribbon outlines the narrow path of the annular eclipse, starting at sunrise in Saudi Arabia (at left) and then ending at sunset over the North Pacific Ocean (at right). It takes the moon’s antumbral shadow some 3 1/3 hours to traverse this 8,000 mile (12,900 km) annular eclipse path, which has a width varying from 73 miles (117 km) wide at the path’s center to 100 miles (over 160 km) wide at the path’s beginning and ending points.

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

The narrow annular eclipse path (in red) starts at sunrise at left ,over Saudi Arabia. and ends at sunset at right over the North Pacific ocean. The annular eclipse takes 3 1/3 hours to traverse this 8,000 mile (12,900 km) path. At any one point on the path, however, the maximum duration of the annular eclipse is only 3 2/3 minutes. Visit EclipseWise.com for an extended version of the above map, or see TimeAndDate.com for a detailed map and local eclipse times.

Animated version of the above map. The small dot depicts the path of the annular eclipse, whereas the much larger circle surrounding the small dot shows the viewing area for a partial solar eclipse.

The annular eclipse is visible from some parts of Saudi Arabia, Qatar, United Arab Emirates, Oman, India, Sri Lanka, Malaysia, Indonesia, Singapore, Northern Mariana Islands, and Guam. Outside the long and narrow road of the annular eclipse, a much broader swath of the world can watch varying degrees of a partial eclipse. The farther north or south you are from the annular eclipse path, the shallower the partial solar eclipse in your sky. The numbers on the map (0.80, 0.60, 0.40, 0.20) tell you the eclipse magnitude – the portion of the sun’s diameter that is covered over by the moon. To find out if and when this eclipse comes to your part of the world, try the wonderful resources below, which give the eclipse times in local time (no conversion from Universal Time to local time is necessary):

Eclipse map and local eclipse times via TimeandDate

Local eclipse times for numerous cities via EclipseWise

If you live along the annular eclipse path, be mindful that a partial eclipse precedes and follows the short-lived annular eclipse. We give the eclipse times for some cities along the path of annularity in local time (no conversion necessary):

Hofuf, Saudi Arabia
Sunrise (partial eclipse in progress): 6:25 a.m. local time (December 26)
Annular eclipse begins: 6:34:39 a.m. (December 26)
Maximum eclipse: 6:36:06 a.m. (December 26)
Annular eclipse ends: 6:37 a.m. (December 26)
Partial eclipse ends: 7:48:34 a.m.(December 26)

Kannur, India
Partial eclipse begins: 8:04:56 a.m. local time (December 26)
Annular eclipse begins: 9:24:53 a.m. (December 26)
Maximum eclipse: 9:26:20 a.m. (December 26)
Annular eclipse ends: 9:27:47 a.m. (December 26)
Partial eclipse ends: 11:05:34 a.m.(December 26)

Jaffna, Sri Lanka
Partial eclipse begins: 8:09:03 a.m. local time (December 26)
Annular eclipse begins: 9:33:57 a.m. (December 26)
Maximum eclipse: 9:35:30 a.m. (December 26)
Annular eclipse ends: 9:37:09 a.m. (December 26)
Partial eclipse ends: 11:21:14 a.m.(December 26)

Singapore, Singapore
Partial eclipse begins: 11:27:09 a.m. local time (December 26)
Annular eclipse begins: 1:22:43 p.m. (December 26)
Maximum eclipse: 1:24:42 p.m. (December 26)
Annular eclipse ends: 1:24:41 p.m. (December 26)
Partial eclipse ends: 3:18:26 p.m.(December 26)

Sri Aman, Malaysia
Partial eclipse begins: 11:52:11 a.m. local time (December 26)
Annular eclipse begins: 1:49:44 p.m. (December 26)
Maximum eclipse: 1:51:26 p.m. (December 26)
Annular eclipse ends: 1:53:07 p.m. (December 26)
Partial eclipse ends: 3:36:42 p.m.(December 26)

Sarangani Island, Philippines
Partial eclipse begins: 12:44:06 p.m. local time (December 26)
Annular eclipse begins: 2:29:43 p.m. (December 26)
Maximum eclipse: 2:30:53 p.m. (December 26)
Annular eclipse ends: 2:32:08 p.m. (December 26)
Partial eclipse ends: 3:57:22 p.m.(December 26)

Source: TimeandDate

Dates for the moon’s phases in 2019 via Astropixels. P = partial solar eclipse, T = total solar eclipse, and A = annular eclipse.

Six lunar months (six new moons) before this December 26th annular eclipse, there was a total eclipse of the sun on July 2, 2019. Back then, the new moon was some 10,000 miles (16,000 km) closer than the new moon of December 2019. Moreover, the sun in early July is about 3 million miles (5 million km) farther away than it is in late December. That all adds up to a total solar eclipse on July 2 (maximum duration: 4 minutes and 33 seconds), yet an annular eclipse on December 26 (maximum duration: 3 minutes and 40 seconds).

The longest lasting total solar solar eclipses happen when the moon is near perigee (closest point to Earth in its monthly orbit) and the Earth is near aphelion (farthest point from the sun). The longest total solar eclipse of the 21st century (2001 to 2100) took place on July 22, 2009, with a duration of 6 minutes and 39 seconds.

Annular eclipse of January 15, 2010, as seen in Bangui, Central African Republic, at 05:19:14 UTC (6:19 local time) via Tino Kreutzer.

On the other hand, the longest lasting annular eclipses happen when the moon is near apogee (its farthest point from Earth in its monthly orbit) and the Earth is near perihelion (closest point to the sun). The longest annular eclipse of the 21st century happened on January 15, 2010, or exactly 6 lunar months (6 new moons) after the century’s longest total solar eclipse on July 22, 2009. The annular eclipse of January 15, 2010, had a duration of 11 minutes and 8 seconds.

If we extend the period to 10,000 years (4,000 B.C. to 6,000 A.D.), rather than just one century, we find the longest total solar eclipse occurring on July 16, 2186 (7 minutes and 29 seconds) and the longest annular eclipse on December 7, 150 (12 minutes and 24 seconds).

Read more: Middle of eclipse season December 30

Correction: We mistakenly said in an earlier version of this article that – for an annular solar eclipse to occur – the new moon has to be near apogee, the farthest point in its orbit around Earth. The mistake was made in editing. As Bruce later pointed out, it’s true sometimes that – during an annular eclipse – the moon is near apogee. But that isn’t the case for the December 26 eclipse. In fact, the December new moon is almost exactly at its mean distance from Earth. Yet – at mid-eclipse – the moon is too small to cover the sun’s disk completely. Why? The answer is that – at this time of year – Earth is close to perihelion, its closest point to the sun for the year. In 2020, Earth’s perihelion will come on January 5 at 07:48 UTC (at 1:48 a.m. CST). So, in our sky around now, the sun’s disk appears slightly larger than usual: hence, the December 26, 2019 annular solar eclipse. Cool, yes? Now consider this: the longest-lasting annular eclipses do occur when the moon is near apogee and the Earth is near perihelion. The annular eclipse on December 26 is not a particularly long-lasting annular eclipse.

Bottom line: The 3rd and final solar eclipse of the year falls on December 26. It’s 2019’s only annular or “ring” eclipse. At mid-eclipse, a ring of the sun’s surface will appear around the moon.

from EarthSky https://ift.tt/39c1QGY

Get ready for the ’20s!

Can you believe this is a century ago?

Reprinted with permission from Jay Ryan at Classical Astronomy

Another decade has passed quickly and here we are on the threshold of yet another. For those of us of a certain age, it’s kind of mind-blowing that the ’20s are here again, and that the decade of the Roaring ’20s is already a century gone by. My grandmother told me stories of her days as a flapper who danced the Charleston. It’s already 100 years since Prohibition and Bonnie and Clyde and all that. Wonder what the 2020s will one day be famous for?

For my own part, I’m glad to be getting back to a decade that has a name and an identity. Anybody besides me notice that the past two decades have been nameless? I mean, I grew up in the ’60s and ’70s and those decades were known by those names, as were the ’80s and ’90s that followed.

I remember asking people in the late ’90s, as the Y2K scare loomed, what will we call the next decade? The ’00s??? How about the 2000s???? But notice that nobody ever called that decade anything at all. And so the first decade of the 21st century still remains nameless to this day. Nobody really talks about it. Same with the current decade now ending. The ’10s??? The Teens??? Nobody says either of those either.

Think about it … you had the ’70s, the ’80s, and then the ’90s, followed by the… um … Well then that decade was followed by the … uhhh … See what I mean? Suppose someday they want to make a nostalgia TV program like “That ’70s Show,” only set in 2004. Will they have to call it “That … Um … Show<"? EarthSky 2020 lunar calendars are available! They make great gifts. Order now. Going fast!

The first decade of the 20th century was sometimes called the Oughts, as in, “Why sonny, I bought my first Model T back in ‘Ought-Nine”. But that’s not how people talk today. The current decade is not properly the Teens either, due the idiosyncrasies of the English language. Ten is not a teen and neither are 11 and 12. So the decade of the Teens would be a third over before you ever got to 13.

Some people have their own theories about what these past two decades should be called. My one friend calls the first decade of the 21st century the Oh-Oughts. Well, that’s one of him and zero of everybody else. We need a consensus!

If something has a name, it has an identity. When someone says the ’60s it conjures up images of hippies and moon landings. The ’70s evokes disco and double-digit inflation, and the ’80s connotes MTV and video arcades. These decades were always mentioned by name during their times and were the subject of daily conversation by everyone. But not so since 2000. The nameless decades of the ’00s and the ’10s have no such identities, though certainly enough notable and iconic events have happened in those decades to distinguish them.

An entire generation has come of age growing up in these nameless, faceless, unidentified decades. So these young people might be in for a surprise when the TV media and the average people on the street will all of a sudden be talking about the ’20s all day, every day, just like we all did back in the ’60s, ’70s, ’80s and ’90s. Thus, the sequence of named decades is about to resume again, and will likely continue until the year 2100.

So the ’20s will begin on January 1, 2020. Or will they? There’s always some pedantic killjoy who insists that the new decade does not begin on the 0th year of the decade. We heard a lot from these people 20 years ago, in 1999, when they were insisting that the 21st century woouldn’t begin in 2000, that we had to wait until 2001. See, according to the Christian calendar, Jesus was born in the year 1, not the year 0, so the first decade ended in A.D. 10, and the next decade began in A.D. 11.

Continue the same process for another two millennia and you have the decade of the 2010s ending in 2020. The ’20s must then begin in 2021. Well that’s no fun at all! So I respectfully submit that any random 10 year interval can be arbitrarily grouped into a decade. So how about we make it simple and all agree that the random 10 year interval that arbitrarily begins in 2020 be collectively regarded as the ’20s? Case closed!

Speaking of which, for the last two decades, lots of people (like me) have been counting the years according to two-thousand-whatever. For example, the year that is about to end has been called two-thousand-nineteen. There have been some people who have called the years by twenty-whatever, as in twenty-nineteen. But these folks have mostly been the outliers. The reason for this is simple. The first year of the current reckoning was the long-anticipated year two-thousand. I mean, what else was anyone going to call it? Twenty-oh-oh? No one said that. So then it followed that the next year would be two-thousand-one, just like the movie. That year was then followed by two-thousand-two and so on, until the current year about to end.

I predict that’s about to change for everyone, and change for good. Probably no one is going to say two-thousand-twenty. I mean, twenty-twenty is just plain catchy. It’s the number of perfect eyesight. So after this next new year ends, it will then follow that the next year after that will be twenty-twenty-one, followed by twenty-twenty-two and so on. This will continue all the way up to twenty-ninety-nine which most people today will not be counting. In the meantime, only the cranky old hold-outs from the 20th century will still insist on saying two-thousand-thirty-two after another dozen years.

It’s surprising to me that no one else has been talking about any of this yet. It’s an issue that will impact all our lives. But let’s wait another month or so to see how the ’20s get going and we’ll all find out together!

Bottom line: Looking ahead to the new decade of the 2020s.

from EarthSky https://ift.tt/395g7Fb

Can you believe this is a century ago?

Reprinted with permission from Jay Ryan at Classical Astronomy

Another decade has passed quickly and here we are on the threshold of yet another. For those of us of a certain age, it’s kind of mind-blowing that the ’20s are here again, and that the decade of the Roaring ’20s is already a century gone by. My grandmother told me stories of her days as a flapper who danced the Charleston. It’s already 100 years since Prohibition and Bonnie and Clyde and all that. Wonder what the 2020s will one day be famous for?

For my own part, I’m glad to be getting back to a decade that has a name and an identity. Anybody besides me notice that the past two decades have been nameless? I mean, I grew up in the ’60s and ’70s and those decades were known by those names, as were the ’80s and ’90s that followed.

I remember asking people in the late ’90s, as the Y2K scare loomed, what will we call the next decade? The ’00s??? How about the 2000s???? But notice that nobody ever called that decade anything at all. And so the first decade of the 21st century still remains nameless to this day. Nobody really talks about it. Same with the current decade now ending. The ’10s??? The Teens??? Nobody says either of those either.

Think about it … you had the ’70s, the ’80s, and then the ’90s, followed by the… um … Well then that decade was followed by the … uhhh … See what I mean? Suppose someday they want to make a nostalgia TV program like “That ’70s Show,” only set in 2004. Will they have to call it “That … Um … Show<"? EarthSky 2020 lunar calendars are available! They make great gifts. Order now. Going fast!

The first decade of the 20th century was sometimes called the Oughts, as in, “Why sonny, I bought my first Model T back in ‘Ought-Nine”. But that’s not how people talk today. The current decade is not properly the Teens either, due the idiosyncrasies of the English language. Ten is not a teen and neither are 11 and 12. So the decade of the Teens would be a third over before you ever got to 13.

Some people have their own theories about what these past two decades should be called. My one friend calls the first decade of the 21st century the Oh-Oughts. Well, that’s one of him and zero of everybody else. We need a consensus!

If something has a name, it has an identity. When someone says the ’60s it conjures up images of hippies and moon landings. The ’70s evokes disco and double-digit inflation, and the ’80s connotes MTV and video arcades. These decades were always mentioned by name during their times and were the subject of daily conversation by everyone. But not so since 2000. The nameless decades of the ’00s and the ’10s have no such identities, though certainly enough notable and iconic events have happened in those decades to distinguish them.

An entire generation has come of age growing up in these nameless, faceless, unidentified decades. So these young people might be in for a surprise when the TV media and the average people on the street will all of a sudden be talking about the ’20s all day, every day, just like we all did back in the ’60s, ’70s, ’80s and ’90s. Thus, the sequence of named decades is about to resume again, and will likely continue until the year 2100.

So the ’20s will begin on January 1, 2020. Or will they? There’s always some pedantic killjoy who insists that the new decade does not begin on the 0th year of the decade. We heard a lot from these people 20 years ago, in 1999, when they were insisting that the 21st century woouldn’t begin in 2000, that we had to wait until 2001. See, according to the Christian calendar, Jesus was born in the year 1, not the year 0, so the first decade ended in A.D. 10, and the next decade began in A.D. 11.

Continue the same process for another two millennia and you have the decade of the 2010s ending in 2020. The ’20s must then begin in 2021. Well that’s no fun at all! So I respectfully submit that any random 10 year interval can be arbitrarily grouped into a decade. So how about we make it simple and all agree that the random 10 year interval that arbitrarily begins in 2020 be collectively regarded as the ’20s? Case closed!

Speaking of which, for the last two decades, lots of people (like me) have been counting the years according to two-thousand-whatever. For example, the year that is about to end has been called two-thousand-nineteen. There have been some people who have called the years by twenty-whatever, as in twenty-nineteen. But these folks have mostly been the outliers. The reason for this is simple. The first year of the current reckoning was the long-anticipated year two-thousand. I mean, what else was anyone going to call it? Twenty-oh-oh? No one said that. So then it followed that the next year would be two-thousand-one, just like the movie. That year was then followed by two-thousand-two and so on, until the current year about to end.

I predict that’s about to change for everyone, and change for good. Probably no one is going to say two-thousand-twenty. I mean, twenty-twenty is just plain catchy. It’s the number of perfect eyesight. So after this next new year ends, it will then follow that the next year after that will be twenty-twenty-one, followed by twenty-twenty-two and so on. This will continue all the way up to twenty-ninety-nine which most people today will not be counting. In the meantime, only the cranky old hold-outs from the 20th century will still insist on saying two-thousand-thirty-two after another dozen years.

It’s surprising to me that no one else has been talking about any of this yet. It’s an issue that will impact all our lives. But let’s wait another month or so to see how the ’20s get going and we’ll all find out together!

Bottom line: Looking ahead to the new decade of the 2020s.

from EarthSky https://ift.tt/395g7Fb

Solstice sunrise over Monterrey, Mexico

View at EarthSky Community Photos. | Raul Cortes of Monterrey, Mexico caught these sunrise photos on the day of the solstice, December 21, 2019. Start here and scroll down to watch the sunrise! Thank you, Raul.

View at EarthSky Community Photos. | Image via Raul Cortes.

View at EarthSky Community Photos. | Image via Raul Cortes.

View at EarthSky Community Photos. | Image via Raul Cortes.

View at EarthSky Community Photos. | Image via Raul Cortes. He wrote: “He wrote, “The sun shows at the bottom of the saddle, between the two peaks that form the Horse Saddle Hill (Cerro de la Silla).” Thank you, Raul!

Bottom line: Photos of the December solstice sunrise – December 21, 2019 – as captured from Monterrey, Mexico.

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

View at EarthSky Community Photos. | Raul Cortes of Monterrey, Mexico caught these sunrise photos on the day of the solstice, December 21, 2019. Start here and scroll down to watch the sunrise! Thank you, Raul.

View at EarthSky Community Photos. | Image via Raul Cortes.

View at EarthSky Community Photos. | Image via Raul Cortes.

View at EarthSky Community Photos. | Image via Raul Cortes.

View at EarthSky Community Photos. | Image via Raul Cortes. He wrote: “He wrote, “The sun shows at the bottom of the saddle, between the two peaks that form the Horse Saddle Hill (Cerro de la Silla).” Thank you, Raul!

Bottom line: Photos of the December solstice sunrise – December 21, 2019 – as captured from Monterrey, Mexico.

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

How can I see Southern Cross now?

A reader asked:

When can I see the Southern Cross in Hawaii?

The answer is now – late December and early January – but you’ll have to look for it at just the right place and time of night. Each year at this time, Hawaiians – or those at the latitude of Hawaii – can see the Southern Cross in the southern sky briefly before dawn. The Southern Cross, aka the constellation Crux, stands close to upright, but quite low in the sky, for the latitude of Honolulu. Be sure to find an unobstructed southern horizon. Follow the links below to learn more about the Southern Cross.

How far south do I have to be to see the Southern Cross?

Are there guide stars to the Southern Cross?

How else can I know if the Southern Cross is visible in my sky?

From the latitude of Hawaii (see arrow), or farther south, you can see the Southern Cross before sunrise in late December and early January. Map via WorldAtlas.com.

How far south do I have to be to see the Southern Cross? Hawaii is at 21 degrees north latitude. Other cities at about this same latitude include Mecca in Saudi Arabia, Leon and Guanajuato in Mexico, and Hanoi in Vietnam.

All of you at this latitude will be able to see the Southern Cross before dawn for at least another month.

Are you south of Hawaii’s latitude? Then you can see the Southern Cross, Rigel Kentaurus and Hadar all the higher in the sky before dawn now. From Australia or New Zealand – or South America or South Africa – Crux is circumpolar. That is, it circles around the sky’s southern pole and appears for most, if not all, of the night.

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

Rigel Kentaurus (aka Alpha Centauri), Hadar and the Southern Cross.

Are there guide stars to the Southern Cross? Look at the photo at the top of this post, by Jv Noriega in the Philippines. Also look at the chart above. Notice the two stars, Rigel Kentaurus and Hadar, in the constellation Centaurus. Rigel Kentaurus is also known as Alpha Centauri, the star system nearest to Earth, at a little more than 4 light-years away.

Rigel Kentaurus (Alpha Centauri) and Hadar point to the Southern Cross.

If you can see the constellation Cassiopeia in your northern sky, then the Southern Cross is below your horizon. Cassiopeia is shaped like the letter M or W.

How else can I know if the Southern Cross is visible in my sky? If you know a bit about the sky, then there is one surefire way to know if the Southern Cross is visible in your sky. When the easy-to-find constellation Cassiopeia the Queen is visible in your sky, the Southern Cross is below your horizon. So, for example, Cassiopeia lights up Hawaiian skies on winter evenings, but it sets beneath Hawaii’s northern horizon several hours before sunrise. As Cassiopeia sets, the Southern Cross rises.

Meanwhile, for latitudes north of Hawaii (for example, most of the continental U.S. – except for southern Florida and Texas), Cassiopeia is circumpolar. It circles endlessly around the sky’s north pole and never sets. Therefore, the Southern Cross never rises as seen from northerly latitudes.

The Southern Cross marks the southern terminus of the glowing band of stars that we call the Milky Way – really the edgewise view into our own Milky Way galaxy. Meanwhile, Cassiopeia lodges at the Milky Way’s northern terminus in our sky.

Matthew Chin in Hong Kong caught Crux – aka the Southern Cross – on December 21, 2017.

Bottom line: Late December and early January are a good time for those at northerly latitudes – latitude of Hawaii or comparable latitudes – to look before dawn for the Southern Cross. It is visible briefly before dawn. Hawaii is at 21 degrees north latitude. Other cities at about this same latitude include Mecca in Saudi Arabia, Leon and Guanajuato in Mexico, and Hanoi in Vietnam.

Southern Cross: Signpost of southern skies

Alpha Centauri: Closest star system to our sun

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A reader asked:

When can I see the Southern Cross in Hawaii?

The answer is now – late December and early January – but you’ll have to look for it at just the right place and time of night. Each year at this time, Hawaiians – or those at the latitude of Hawaii – can see the Southern Cross in the southern sky briefly before dawn. The Southern Cross, aka the constellation Crux, stands close to upright, but quite low in the sky, for the latitude of Honolulu. Be sure to find an unobstructed southern horizon. Follow the links below to learn more about the Southern Cross.

How far south do I have to be to see the Southern Cross?

Are there guide stars to the Southern Cross?

How else can I know if the Southern Cross is visible in my sky?

From the latitude of Hawaii (see arrow), or farther south, you can see the Southern Cross before sunrise in late December and early January. Map via WorldAtlas.com.

How far south do I have to be to see the Southern Cross? Hawaii is at 21 degrees north latitude. Other cities at about this same latitude include Mecca in Saudi Arabia, Leon and Guanajuato in Mexico, and Hanoi in Vietnam.

All of you at this latitude will be able to see the Southern Cross before dawn for at least another month.

Are you south of Hawaii’s latitude? Then you can see the Southern Cross, Rigel Kentaurus and Hadar all the higher in the sky before dawn now. From Australia or New Zealand – or South America or South Africa – Crux is circumpolar. That is, it circles around the sky’s southern pole and appears for most, if not all, of the night.

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

Rigel Kentaurus (aka Alpha Centauri), Hadar and the Southern Cross.

Are there guide stars to the Southern Cross? Look at the photo at the top of this post, by Jv Noriega in the Philippines. Also look at the chart above. Notice the two stars, Rigel Kentaurus and Hadar, in the constellation Centaurus. Rigel Kentaurus is also known as Alpha Centauri, the star system nearest to Earth, at a little more than 4 light-years away.

Rigel Kentaurus (Alpha Centauri) and Hadar point to the Southern Cross.

If you can see the constellation Cassiopeia in your northern sky, then the Southern Cross is below your horizon. Cassiopeia is shaped like the letter M or W.

How else can I know if the Southern Cross is visible in my sky? If you know a bit about the sky, then there is one surefire way to know if the Southern Cross is visible in your sky. When the easy-to-find constellation Cassiopeia the Queen is visible in your sky, the Southern Cross is below your horizon. So, for example, Cassiopeia lights up Hawaiian skies on winter evenings, but it sets beneath Hawaii’s northern horizon several hours before sunrise. As Cassiopeia sets, the Southern Cross rises.

Meanwhile, for latitudes north of Hawaii (for example, most of the continental U.S. – except for southern Florida and Texas), Cassiopeia is circumpolar. It circles endlessly around the sky’s north pole and never sets. Therefore, the Southern Cross never rises as seen from northerly latitudes.

The Southern Cross marks the southern terminus of the glowing band of stars that we call the Milky Way – really the edgewise view into our own Milky Way galaxy. Meanwhile, Cassiopeia lodges at the Milky Way’s northern terminus in our sky.

Matthew Chin in Hong Kong caught Crux – aka the Southern Cross – on December 21, 2017.

Bottom line: Late December and early January are a good time for those at northerly latitudes – latitude of Hawaii or comparable latitudes – to look before dawn for the Southern Cross. It is visible briefly before dawn. Hawaii is at 21 degrees north latitude. Other cities at about this same latitude include Mecca in Saudi Arabia, Leon and Guanajuato in Mexico, and Hanoi in Vietnam.

Southern Cross: Signpost of southern skies

Alpha Centauri: Closest star system to our sun

Purchase a planisphere – or guide to the stars – an essential tool for beginning stargazers.

from EarthSky https://ift.tt/2ZiP8Sd

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

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!

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.

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.

I just took this shot of Orion and Taurus. Betelgeuse (left bright star) is noticeably dimmer than usual. It's at best as bright as Aldebaran (near the top) and dimmer than Rigel (right). No, this doesn't mean it's about to blow. It's a variable star and… https://t.co/dzDIdXk4v5 pic.twitter.com/oKWZJmgDmi

— Phil Plait (@BadAstronomer) December 21, 2019

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.

#ICYMI Betelgeuse is fainting (yes, that's the right technical term ????).

The variable red supergiant star is 11x more massive than the Sun, but has a radius 887x bigger, so its mean density is 63 million x lower.

That's just 22 milligrams per cubic metre.

Bonkers, eh? ? https://t.co/cQJuno2ybV

— Mark McCaughrean (@markmccaughrean) December 21, 2019

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.

Regarding #Betelgeuse's "historic" dimming, here's V-band & photovis magnitude estimates from @AAVSO database over past century.
*You* try maintaining constant luminosity w/~20 solar masses spread out within the size of Jupiter's orbit, w/convection & nucleosynthesis is 3D! pic.twitter.com/e2kojEZXAC

— Eric Mamajek (@EricMamajek) December 21, 2019

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.

Astroblog: Betelgeuse fades more. This historic dimming of Betelgeuse continues,and it is now observably dimmer than Aldebaran? Will it fade more, go out and have a look.https://t.co/GcAI7EIyHA pic.twitter.com/GL2bBsvpxP

— ? Ian Musgrave (@ianfmusgrave) December 20, 2019

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

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!

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.

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.

I just took this shot of Orion and Taurus. Betelgeuse (left bright star) is noticeably dimmer than usual. It's at best as bright as Aldebaran (near the top) and dimmer than Rigel (right). No, this doesn't mean it's about to blow. It's a variable star and… https://t.co/dzDIdXk4v5 pic.twitter.com/oKWZJmgDmi

— Phil Plait (@BadAstronomer) December 21, 2019

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.

#ICYMI Betelgeuse is fainting (yes, that's the right technical term ????).

The variable red supergiant star is 11x more massive than the Sun, but has a radius 887x bigger, so its mean density is 63 million x lower.

That's just 22 milligrams per cubic metre.

Bonkers, eh? ? https://t.co/cQJuno2ybV

— Mark McCaughrean (@markmccaughrean) December 21, 2019

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.

Regarding #Betelgeuse's "historic" dimming, here's V-band & photovis magnitude estimates from @AAVSO database over past century.
*You* try maintaining constant luminosity w/~20 solar masses spread out within the size of Jupiter's orbit, w/convection & nucleosynthesis is 3D! pic.twitter.com/e2kojEZXAC

— Eric Mamajek (@EricMamajek) December 21, 2019

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.

Astroblog: Betelgeuse fades more. This historic dimming of Betelgeuse continues,and it is now observably dimmer than Aldebaran? Will it fade more, go out and have a look.https://t.co/GcAI7EIyHA pic.twitter.com/GL2bBsvpxP

— ? Ian Musgrave (@ianfmusgrave) December 20, 2019

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

Astronomers find ‘missing’ neutron star after 32 years

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!

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

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!

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

November 2019 was 2nd hottest on record for planet

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.

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

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.

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