Look for the Northern Cross

Tonight, look for the Northern Cross. It isn’t as famous as its counterpart – the Southern Cross – visible from the Southern Hemisphere or the northern tropics. But the Northern Cross also looks like a cross, and it’s pretty easy to spot. It’s a large, noticeable star pattern.

The star Deneb marks the top of the Northern Cross, and the star Albireo marks the bottom. Tonight – or any night in late December – you can find the Northern Cross shining fairly high in the west at nightfall, as seen from mid-northern latitudes. It sinks downward during the evening hours, and stands proudly over the west-northwest horizon around mid-evening.

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Here’s another look at the famous Northern Cross. It’s part of the constellation Cygnus the Swan. Photo via Flickr user Janne.

The Northern Cross is what’s known as an asterism. In other words, it’s not a constellation but simply a noticeable pattern of stars. It’s part of the constellation Cygnus the Swan.

As an added bonus, if you have a pair of binoculars, break them out this evening and point them toward the Northern Cross and its larger constellation Cygnus the Swan. In this direction, you’ll find a part of our Milky Way galaxy that is called the Cygnus Star Cloud. It is part of the spiral arm of our galaxy that also contains our sun, and you should be able to pick out stars from it if the night is clear in your area.

By the way, we get many questions from people in northern latitudes about if and when they can view the Southern Cross in their portion of the sky. The truth is that unless you live close to the tropics (Hawaii, or the southernmost parts of Texas or Florida for those of us in the U.S.), you won’t be able to view the Southern Cross, also known as the constellation Crux. It won’t rise above your horizon. To find out how to locate Crux in Hawaii at this time of year, look here.

Bottom line: Learn to recognize a famous star pattern known as the Northern Cross, which stands upright over the west-northwest horizon in December.

Looking for a sky almanac? EarthSky recommends …

EarthSky lunar calendars make great gifts for astronomy-minded friends and family. Going fast!

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Tonight, look for the Northern Cross. It isn’t as famous as its counterpart – the Southern Cross – visible from the Southern Hemisphere or the northern tropics. But the Northern Cross also looks like a cross, and it’s pretty easy to spot. It’s a large, noticeable star pattern.

The star Deneb marks the top of the Northern Cross, and the star Albireo marks the bottom. Tonight – or any night in late December – you can find the Northern Cross shining fairly high in the west at nightfall, as seen from mid-northern latitudes. It sinks downward during the evening hours, and stands proudly over the west-northwest horizon around mid-evening.

Donate: Your support means the world to us

Here’s another look at the famous Northern Cross. It’s part of the constellation Cygnus the Swan. Photo via Flickr user Janne.

The Northern Cross is what’s known as an asterism. In other words, it’s not a constellation but simply a noticeable pattern of stars. It’s part of the constellation Cygnus the Swan.

As an added bonus, if you have a pair of binoculars, break them out this evening and point them toward the Northern Cross and its larger constellation Cygnus the Swan. In this direction, you’ll find a part of our Milky Way galaxy that is called the Cygnus Star Cloud. It is part of the spiral arm of our galaxy that also contains our sun, and you should be able to pick out stars from it if the night is clear in your area.

By the way, we get many questions from people in northern latitudes about if and when they can view the Southern Cross in their portion of the sky. The truth is that unless you live close to the tropics (Hawaii, or the southernmost parts of Texas or Florida for those of us in the U.S.), you won’t be able to view the Southern Cross, also known as the constellation Crux. It won’t rise above your horizon. To find out how to locate Crux in Hawaii at this time of year, look here.

Bottom line: Learn to recognize a famous star pattern known as the Northern Cross, which stands upright over the west-northwest horizon in December.

Looking for a sky almanac? EarthSky recommends …

EarthSky lunar calendars make great gifts for astronomy-minded friends and family. Going fast!

from EarthSky https://ift.tt/2Q5fVy9

Don’t miss the young moon and Venus

As the year wanes, the young moon returns to the west after sunset.

From virtually everyplace worldwide on December 27, the moon will be better than one day (24 hours) old as the sun sets. If your sky is clear, you can catch the whisker-thin waxing crescent (and possibly, with much more difficulty, the planet Saturn) at dusk. You’ll surely see dazzling Venus, above them, blazing in Friday evening’s western twilight sky. This young moon will be fresh from its ring of fire eclipse a day earlier.

The Western Hemisphere will have the easiest view of the young moon after sunset on December 27. From the Eastern Hemisphere on December 27, the moon will be more challenging, but lots of fun. More about viewing from the Eastern Hemisphere below.

On the following evenings – December 28 and 29 – the moon will be much easier for all. It’ll be closest to Venus Saturday evening, December 28. A wondrous sky scene for the whole world! #OneEarth #OneSky

The bright couple – two brightest lights in our sky after the sun – will be beautiful again on Sunday evening, December 29.

By the way, although we show the planet Saturn on our sky chart above, it’ll take a deliberate effort (and possibly binoculars) to spot this world in the glare of evening twilight.

View larger. | Last year, April Singer caught the young moon after sunset on December 8, 2018, with Saturn to its upper left. This year, you’ll see Venus instead of Saturn to the upper left of the moon (from northerly latitudes). Northern New Mexico, U.S. Photo by April Singer Photography. Way to go, April!

Young moon from Eastern Hemisphere on December 27. We’re not counting out the world’s Eastern Hemisphere on December 27. If you live in that part of the world, you might also catch a young(er) and slender(er) crescent after sunset that evening. From virtually everyplace worldwide, the moon will be better than one day (24 hours) old as the sun sets on December 27. It’s usually quite difficult to see a moon that’s less than one day (24 hours) old. It’s easier – though still a challenge – to spot a thin moon that’s just over a day old.

That challenge will occur for the world’s Eastern Hemisphere on December 27, where the moon will be younger than for us in the West. Look sooner after sunset. Have a totally unobstructed horizon. Bring binoculars!

Day and night sides of Earth one day (24 hours) after new moon (December 27, 2019 at 5:13 UTC). The shadow line at the far right and far left depicts sunset. As the line of sunset moves westward (right to left) across the globe, the moon continually edges farther away from the glare of sunset. The moon will be about 1 1/2 days old at sunset in western Europe and Africa, and about 1 3/4 days old as the sun sets in the Americas. Image via EarthView.

No matter where you live worldwide, you’ll have a better chance of spotting the moon on December 28, because a wider crescent will stay out longer after sundown than on December 27. Additionally, the moon will be closer to Venus on December 28, offering a more stunning view of the evening couple.

To maximize your chances of spotting the beautiful evening crescent (and/or Saturn), find an unobstructed horizon in the direction of sunset. A lofty position – atop a mountain or balcony – would help out as well, enabling you to peek a little farther over the horizon. Binoculars come in handy, too, for teasing out the pale, skinny crescent (or Saturn) from the glare of evening twilight.

Want to know when the moon sets in your sky? The Sunrise and Sunset Calendar gives you the moonset time – but remember to check the Moonrise and moonset box.

Want to know the moon’s position relative to the bright planets and the constellations of the zodiac? Your wish is granted, courtesy of Heavens-Above.com!

When the moon shows itself as a slender waxing crescent in Earth’s sky, then our planet beams a nearly-full waning gibbous Earth in the moon’s sky. The almost-full Earth, like a mirror, reflects sunlight and lights up the moon’s dark side. The moon, in turn, reflects sunlight back to Earth. Hence, that soft luminescence giving definition to the nighttime side of the moon is earthshine – twice-reflected sunlight. Look for soft glow of earthshine, with either the unaided eye or binoculars, on the dark side of the moon over the next several days.

View larger at EarthSky Community Photos. Peter Lowenstein of Mutare, Zimbabwe, caught the old waning crescent moon (and the planet Mercury to the moon’s lower right) in the east before sunrise December 25, 2019. To catch the upcoming young moon, look westward after sunset on December 27, 2019. Good luck! Thank you Peter!

Bottom line: Think photo opportunity this weekend (December 27-29, 2019) as the brightest and 2nd-brightest sky objects – the moon and Venus – beautify the evening twilight shortly after sunset.

from EarthSky https://ift.tt/351ddOC

As the year wanes, the young moon returns to the west after sunset.

From virtually everyplace worldwide on December 27, the moon will be better than one day (24 hours) old as the sun sets. If your sky is clear, you can catch the whisker-thin waxing crescent (and possibly, with much more difficulty, the planet Saturn) at dusk. You’ll surely see dazzling Venus, above them, blazing in Friday evening’s western twilight sky. This young moon will be fresh from its ring of fire eclipse a day earlier.

The Western Hemisphere will have the easiest view of the young moon after sunset on December 27. From the Eastern Hemisphere on December 27, the moon will be more challenging, but lots of fun. More about viewing from the Eastern Hemisphere below.

On the following evenings – December 28 and 29 – the moon will be much easier for all. It’ll be closest to Venus Saturday evening, December 28. A wondrous sky scene for the whole world! #OneEarth #OneSky

The bright couple – two brightest lights in our sky after the sun – will be beautiful again on Sunday evening, December 29.

By the way, although we show the planet Saturn on our sky chart above, it’ll take a deliberate effort (and possibly binoculars) to spot this world in the glare of evening twilight.

View larger. | Last year, April Singer caught the young moon after sunset on December 8, 2018, with Saturn to its upper left. This year, you’ll see Venus instead of Saturn to the upper left of the moon (from northerly latitudes). Northern New Mexico, U.S. Photo by April Singer Photography. Way to go, April!

Young moon from Eastern Hemisphere on December 27. We’re not counting out the world’s Eastern Hemisphere on December 27. If you live in that part of the world, you might also catch a young(er) and slender(er) crescent after sunset that evening. From virtually everyplace worldwide, the moon will be better than one day (24 hours) old as the sun sets on December 27. It’s usually quite difficult to see a moon that’s less than one day (24 hours) old. It’s easier – though still a challenge – to spot a thin moon that’s just over a day old.

That challenge will occur for the world’s Eastern Hemisphere on December 27, where the moon will be younger than for us in the West. Look sooner after sunset. Have a totally unobstructed horizon. Bring binoculars!

Day and night sides of Earth one day (24 hours) after new moon (December 27, 2019 at 5:13 UTC). The shadow line at the far right and far left depicts sunset. As the line of sunset moves westward (right to left) across the globe, the moon continually edges farther away from the glare of sunset. The moon will be about 1 1/2 days old at sunset in western Europe and Africa, and about 1 3/4 days old as the sun sets in the Americas. Image via EarthView.

No matter where you live worldwide, you’ll have a better chance of spotting the moon on December 28, because a wider crescent will stay out longer after sundown than on December 27. Additionally, the moon will be closer to Venus on December 28, offering a more stunning view of the evening couple.

To maximize your chances of spotting the beautiful evening crescent (and/or Saturn), find an unobstructed horizon in the direction of sunset. A lofty position – atop a mountain or balcony – would help out as well, enabling you to peek a little farther over the horizon. Binoculars come in handy, too, for teasing out the pale, skinny crescent (or Saturn) from the glare of evening twilight.

Want to know when the moon sets in your sky? The Sunrise and Sunset Calendar gives you the moonset time – but remember to check the Moonrise and moonset box.

Want to know the moon’s position relative to the bright planets and the constellations of the zodiac? Your wish is granted, courtesy of Heavens-Above.com!

When the moon shows itself as a slender waxing crescent in Earth’s sky, then our planet beams a nearly-full waning gibbous Earth in the moon’s sky. The almost-full Earth, like a mirror, reflects sunlight and lights up the moon’s dark side. The moon, in turn, reflects sunlight back to Earth. Hence, that soft luminescence giving definition to the nighttime side of the moon is earthshine – twice-reflected sunlight. Look for soft glow of earthshine, with either the unaided eye or binoculars, on the dark side of the moon over the next several days.

View larger at EarthSky Community Photos. Peter Lowenstein of Mutare, Zimbabwe, caught the old waning crescent moon (and the planet Mercury to the moon’s lower right) in the east before sunrise December 25, 2019. To catch the upcoming young moon, look westward after sunset on December 27, 2019. Good luck! Thank you Peter!

Bottom line: Think photo opportunity this weekend (December 27-29, 2019) as the brightest and 2nd-brightest sky objects – the moon and Venus – beautify the evening twilight shortly after sunset.

from EarthSky https://ift.tt/351ddOC

Photos of December 26 ‘ring of fire’ eclipse

Get the details of this annular solar eclipse here.

View at EarthSky Community Photos. | Progression into and out of yesterday’s annular eclipse, from Tumon Bay, Guam. Eliot Herman reported: “It was a beautiful day in Guam to observe the eclipse mostly clear blue skies with a little marine haze on the coast. These images were captured with a Questar telescope and a Nikon D850 camera using a Baader solar filter.” Thank you, Eliot!

View at EarthSky Community Photos. | Dr Ski at Valencia, Philippines wrote: “The sun at maximum coverage from my location.” Thank you, Dr Ski!

View at EarthSky Community Photos. | Nikunj Rawal wrote from Jamnagar, Gujarat, India: “…73% maximum eclipse at 09:17 a.m. at Jamnagar, India on December 26. Was worth experience to witness and capture the phenomenon using a long-focal-length telephoto lens with well planned preparations of 2 weeks on top of the Gop Hills Mountain. The annular phase of this solar eclipse was not visible here, unlike South Indian states. This sequence is a combination of 2 consecutive exposures taken with the same camera using the same settings — one taken of the landscape and another of the background of sun using 3.8mm Baader filter.” Thank you, Nikunj!

View at EarthSky Community Photos. | Kannan A wrote from Singapore: “On this day – December 26, 2019 – in Singapore, we got to see the annular solar eclipse. It was a very rare moment on this day which coincided with Boxing Day and the 15th anniversary of the 2004 Tsunami in Banda Aceh. During the maximum phase of the eclipse, the clouds formed momentarily allowing stargazers to view the eclipse without the use of specialized equipment, but with precautions taken to protect the eyes. In the north of Singapore, Woodlands, however, I did not get to see the ring of fire but got a pleasant Christmas C!” Thank you, Kannan A!

View at EarthSky Community Photos. | A final word from Kannan A! Thank you!

Bottom line: Photos from the EarthSky Community of the December 26, 2019 annular or ‘ring of fire’ solar eclipse. The annular eclipse was viewed across a narrow track that started at sunrise in Saudi Arabia and ended at sunset over the North Pacific Ocean. Outside that track, many more viewed a partial eclipse.

Get the details of this annular solar eclipse here.

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

Get the details of this annular solar eclipse here.

View at EarthSky Community Photos. | Progression into and out of yesterday’s annular eclipse, from Tumon Bay, Guam. Eliot Herman reported: “It was a beautiful day in Guam to observe the eclipse mostly clear blue skies with a little marine haze on the coast. These images were captured with a Questar telescope and a Nikon D850 camera using a Baader solar filter.” Thank you, Eliot!

View at EarthSky Community Photos. | Dr Ski at Valencia, Philippines wrote: “The sun at maximum coverage from my location.” Thank you, Dr Ski!

View at EarthSky Community Photos. | Nikunj Rawal wrote from Jamnagar, Gujarat, India: “…73% maximum eclipse at 09:17 a.m. at Jamnagar, India on December 26. Was worth experience to witness and capture the phenomenon using a long-focal-length telephoto lens with well planned preparations of 2 weeks on top of the Gop Hills Mountain. The annular phase of this solar eclipse was not visible here, unlike South Indian states. This sequence is a combination of 2 consecutive exposures taken with the same camera using the same settings — one taken of the landscape and another of the background of sun using 3.8mm Baader filter.” Thank you, Nikunj!

View at EarthSky Community Photos. | Kannan A wrote from Singapore: “On this day – December 26, 2019 – in Singapore, we got to see the annular solar eclipse. It was a very rare moment on this day which coincided with Boxing Day and the 15th anniversary of the 2004 Tsunami in Banda Aceh. During the maximum phase of the eclipse, the clouds formed momentarily allowing stargazers to view the eclipse without the use of specialized equipment, but with precautions taken to protect the eyes. In the north of Singapore, Woodlands, however, I did not get to see the ring of fire but got a pleasant Christmas C!” Thank you, Kannan A!

View at EarthSky Community Photos. | A final word from Kannan A! Thank you!

Bottom line: Photos from the EarthSky Community of the December 26, 2019 annular or ‘ring of fire’ solar eclipse. The annular eclipse was viewed across a narrow track that started at sunrise in Saudi Arabia and ended at sunset over the North Pacific Ocean. Outside that track, many more viewed a partial eclipse.

Get the details of this annular solar eclipse here.

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

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.

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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.

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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.

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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

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

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

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