Counter Glow

Written by The Night Sky Guy on December 10, 2015 – 3:48 pm -

Image Credit & Copyright: Yuri Beletsky (Las Campanas Observatory, Carnegie Institution)

Starting on Friday, December 11, and into the next week, look under dark skies before dawn for the elusive sky glow known as Gegenschein, which is German for “counter glow.”

Gegenschein is a faint, circular glowing area in the sky opposite from the sun and is similar to the zodiacal lights, which look like a cone of light in the direction of the sun at morning or evening twilight. The diffuse patch of light of the counter glow is caused by the backscattering of light off dust spread out between planets in the solar system, but it is usually blocked from Earth viewers by light pollution or the moon’s shine. It is best visible when the sky is moonless and the skywatcher is in the dark countryside far from a city.

The counter glow is easiest to spot around local midnight, when sunshine hits the dust particles in space squarely in relation to Earth. This is similar to the uptick in brightness that occurs when a planet is at opposition, or opposite in the sky from the sun. From our vantage point on Earth, Gegenschein appears as a distinctly brighter spot in the sky. Look for a faint, round glow about 10 degrees across, equal to about the width of your fist held at arm’s length.

For this and other celestial events, check out my National Geographic column, Starstruck.


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Whisper Thin Crescent Moon Joins Jupiter, Venus & Mars

Written by The Night Sky Guy on November 6, 2015 – 3:28 pm -

Look towards the eastern predawn skies to view the conjunction of Mars, Venus and the moon with Jupiter.

Look towards the eastern predawn skies on November 7 to view the conjunction of Mars, Venus and the moon with Jupiter.

The early morning of Saturday, November 7, will make for a stunning finale to a celestial dance with the thin crescent moon—only 16 percent lit—slipping below Jupiter and pairing up with the brilliant Venus and Mars.

Earth’s natural satellite will appear only two degrees from the planetary duo, making for an amazing photo opportunity.

Keep in mind that while these worlds may look close together in the sky, they are in fact great distances apart. Venus is six light-minutes away, Mars is 18 light-minutes distant, and Jupiter is so far away that reflected sunlight off its cloud tops takes a whopping 49 minutes to reach our eyes.


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Mars and Venus

Written by The Night Sky Guy on October 31, 2015 – 11:25 am -

God of War and God of Love meet in predawn hours with king of the planets, Jupiter looking down upon them.

God of War and God of Love meet in predawn hours of November 1 with king of the planets, Jupiter looking down upon them.

On Sunday, November 1, early risers get a chance to catch the goddess of love and the god of war team up in the low eastern sky just before dawn when super-bright Venus slides within 1 degree of Mars. The king of the gods, Jupiter, will be perched above, looking down on the pair.

For more night sky events, check out my National Geographic column, Starstruck.


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Demon Star

Written by The Night Sky Guy on October 30, 2015 – 11:20 am -

Halloween night the Demon Star shines in Perseus. While trick or treating, glimpse this famous variable star!

Halloween night the Demon Star shines in Perseus. While trick or treating, glimpse this famous variable star!

On Halloween, Saturday, October 31, trick-or-treaters can hunt down a real stellar ghoul in the sky. That night, the naked-eye star Algol sits in the constellation Perseus, rising high in the northeastern evening sky. The star represents the eye of the monster Medusa from ancient Greek mythology, but what makes it so eerie is that it appears to wink at us.

Algol, which means “ghoul’s head,” sits 93 light-years away and is actually two stars that orbit each other. From our vantage point here on Earth, the two stars are lined up so that one eclipses the other every 2.867 days, or 68 hours, 48 minutes, and 59.9 seconds. That makes Algol appear to fade and brighten.

Known as an eclipsing binary variable, Algol is normally the second-brightest star in the constellation Perseus at 2.1 magnitude, which is about as bright as stars in the Big Dipper. But over a 10-hour period, Algol fades dramatically to 3.4 magnitude and then again brightens, as one star passes in front of the other. This week, Algol reaches its dimmest point at 8:50 a.m. ET on October 27 and 5:39 a.m. ET on October 30.

You can easily hunt down the demon star in the constellation Perseus, the hero, near the W-shaped constellation Cassiopeia and the bright star Capella of the constellation Auriga. Perseus looks somewhat like a lopsided K, with Algol located along one of the upper arms just a few degrees from the bright star Mirfak.

For more night sky events, check out my National Geographic column, Starstruck.


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Moon Passes by Closest Old Star Cluster

Written by The Night Sky Guy on October 6, 2015 – 11:12 am -

Closest Oldest Star Cluster can be seen thanks to nearby Moon on Wednesday, October 7. (Image: Nigel Sharp, Mark Hanna/NOAO/AURA/NSF)

Closest Oldest Star Cluster can be seen thanks to nearby Moon on Wednesday, October 7. (Image: Nigel Sharp, Mark Hanna/NOAO/AURA/NSF)

The moon shows the way to an open cluster in the predawn hours on Wednesday, October 7. The crescent moon will now be parked next to Messier 67, which contains hundreds of geriatric stars that are believed to be at least 3.2 billion years old.  Only a few open clusters are older than M67, but none are closer to Earth. Located in the southwestern sky, this grouping of geriatric stars is in the zodiacal constellation Cancer.


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Moon meets Orion

Written by The Night Sky Guy on October 2, 2015 – 11:19 pm -

 

Picture of the moon perched above the star Betetegeuse that pins down the constellation OrionAwake early on Sunday morning to watch the moon meet Orion in northeastern sky.

The waning moon will rise in the early morning hours in the northeastern sky on Sunday, October 4  and will appear to be perched above the bright constellation Orion, the hunter.

Sky-watchers looking under the moon will be greeted by one of the largest naked-eye stars in the entire sky: Betelgeuse, which marks the left shoulder of Orion. Shining with a distinct orange hue, Betelgeuse is a red giant star that is 700 times the size of our sun. It’s so large, in fact, that if it replaced the sun at the center of our solar system, the edge of Betelgeuse would reach at least to the orbit of Mars.


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Bull’s Eye Blinks Out

Written by The Night Sky Guy on September 30, 2015 – 11:18 pm -

Screen Shot 2015-09-30 at 11.13.34 PM
Moon covers Aldebaran in occultation on Friday, October 2 in North America.

66-light-years distant Aldebaran, the star that represents the red eye of the constellation Taurus, will appear to be eclipsed or occulted by the moon at dawn for viewers on the west coast of North America, and during daylight for the rest of the American continent.

The best way to catch a glimpse of the star-moon pair during daylight will be to use binoculars. Scan to the left of the moon for the star. Aldebaran should reach the limb of the moon at 9:55 a.m. EDT (6:15 a.m. PDT) and will reappear on the other side, the darkened limb of the moon, at 10:52 a.m. EDT (7:15 a.m. PDT).

For more information and more celestial events, check out my National Geographic column.


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Your Guide to the Total Lunar Eclipse This Sunday

Written by The Night Sky Guy on September 25, 2015 – 4:35 pm -

Eclipse time for Eastern Daylight Time. Credit: Sky and Telescope Illustration.

Eclipse time for Eastern Daylight Time. Credit: Sky and Telescope Illustration.

Everyone with clear skies across the Americas will have a front-row seat Sunday night to a rare total eclipse of the super-harvest moon.   

On the evening of September 27, three separate lunar events converge. The total eclipse coincides with the full moon nearest the fall equinox, known as the harvest moon. What’s more, the moon is at its closest approach to Earth for the year, making it also a supermoon or perigee moon. That’s why it’s being coined by some as a Super Harvest Blood Moon—a mouthful to be sure.
This confluence has happened only five times since 1900. According to NASA, the last time we saw this celestial triple combination was in 1982, and it won’t repeat until 2033.

Sept2015_LunarEclipse_worldmap

This world map shows that both Americas, Europe and Africa will get to see at least part of the lunar eclipse on Sept.27, 2015. Credit: Sky and Telescope Illustration.

The most spectacular part of the eclipse will be the totality phase, when Earth’s shadow completely covers the moon and turns it an eerie red. The moon will dip into the deepest and darkest part of Earth’s shadow, or umbra, during the totality phase, which lasts as long as 72 minutes.

This week’s eclipse is even more special because the lunar disk will appear slightly larger than usual. The moon will be at perigee—its closest point to Earth—just 59 minutes before the height of the eclipse. This will make the lunar disk appear 13 percent larger than average.

During the total eclipse, sunlight shining through the ring of Earth’s dusty atmosphere is bent, or refracted, toward the red part of the spectrum and cast onto the moon’s surface.

 

This diagram shows why the moon does not disappear in our skies during a total eclipse. The sunlight travels through Earth's atmosphere and gets refracted by particles towards the red part of the spectrum. Credit: Sky andTelescope Illustration.

This diagram shows why the moon does not disappear in our skies during a total eclipse. The sunlight travels through Earth’s atmosphere and gets refracted by particles towards the red part of the spectrum. Credit: Sky and Telescope Illustration.

As a result, expect to see the lunar disk go from a dark gray color during the partial phase of the eclipse to a reddish-orange color during totality. The moon’s color during totality can vary considerably depending on the amount of dust in the Earth’s atmosphere at the time. Active volcanoes spewing tons of ash into the upper atmosphere, for instance, can trigger blood-red eclipses.
No one can predict exactly what color we’ll see before each eclipse.

What Time Do I Watch?
The first part of the eclipse will be the partial phase, when the moon enters Earth’s dark shadow (umbra) beginning at 9:07 p.m. EDT or 01:07 GMT. From that point, the dark umbral shadow will spread across the moon’s disk from left to right.
At 10:11 p.m. EDT, totality begins—when the moon is fully engulfed in the umbral shadow and turns a shade of orange-red. Totality will last as long as one hour and 12 minutes, with the rest of the visible eclipse ending at 12:27 a.m. EDT.

Eclipse Event                   EDT           CDT            MDT              PDT
Partial eclipse begins         9:07 p.m.  8:07 p.m.
Total eclipse begins          10:11 p.m   9:11 p.m        8:11 p.m         7:11 p.m
Midpoint of eclipse          10:47 p.m.  9:47 p.m.     8:47 p.m.       7:47 p.m.
Total eclipse ends            11:23 p.m.   10:23 p.m.   9:23 p.m.      8:23 p.m.
Partial eclipse ends         12:27 a.m    11:27 p.m.    10:27 p.m.     9:27 p.m.


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Moon Meets Green Giant

Written by The Night Sky Guy on August 3, 2015 – 9:35 pm -

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Moon meets planet Uranus. Credit: A.Fazekas/SkySafari

Near midnight on Tuesday look for the planet Uranus beside the waning gibbous moon as it rises in the east.
The two worlds will be separated by only 3 degrees—less than the width of your three middle fingers held at arm’s length. The planet’s close proximity to the moon will make it easy to locate the magnitude-5.8 ice giant. Because of the lunar glare, however, binoculars will be needed to see the planet’s distinct greenish hue.
For more sky events check out my weekly sky-watcher’s guide over at National Geographic News.


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Best Views of Iconic Summer Triangle

Written by The Night Sky Guy on July 1, 2015 – 6:01 pm -

summer triangle july

Skychart showing the location of the Summer Triangle and its stars and constellations in the July evening sky. Credit: A.Fazekas/SkySafari

While watching fireworks on Independence Day–Saturday, July 4–look for the iconic Summer Triangle riding high in the southern, late night sky.

Not a constellation by itself, the Summer Triangle offers a great three-for-one deal for backyard stargazers. The individual stars not only anchor the triangle but also act as a guide to three separate constellations.

Leading off the triangle at the top is the most brilliant of the group, Vega, which is part of the constellation Lyra, the harp. This powerhouse star, located about 25 light-years away, is twice the size of our sun and burns 50 times brighter. Not surprisingly, it ranks as the fifth brightest star in the entire sky.

The next point of the triangle is Altair, the eye of Aquila, the eagle. It’s the faintest of the three despite being the closest–only 17 light-years distant. According to romantic Chinese legend, Altair is a young man who is in love with the beautiful princess, Vega. Unfortunately, they are destined to be separated forever by the fast flowing river that is the Milky Way.

Finally, the lowest point in this celestial triangle is marked by Deneb, the tail of Cygnus, the swan. But don’t be fooled by its serene appearance. This monster is about 200 times the size of our sun and burns an astonishing 100,000 times brighter, making Vega seem puny by comparison.


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