December 1, 2017

Night Skies: December is a great time to take a look at Orion


The constellation Orion will rise at 6:40 p.m. on December 1 and will completely cover the Eastern horizon by 7:40 p.m. Most sky watchers can easily pick out the stars  that form the body, belt, and sword  of this mythological hunter, but may not realize how much this area of the sky has to offer.

Let’s put a name on some of the major stars in Orion.  The bright red giant in the upper left is Betelgeuse. (Don’t say that name three times fast or you might have Michael Keaton as a visiter!) It’s the ninth brightest star in the night sky with a magnitude of +0.56.  Betelgeuse has a very faint companion star with a visual magnidtue of +14.5.  Betelgeuse is 500 light years away.

To the right of Betelgeuse is Bellatrix. It’s a blue-white star double star with visual magnitudes of +1.65 and +13.  Bellatix is 240 light years away from us.

In the lower right is Rigel.  It’s the brightest star in the constellation, with visual magnitude of +0.2. Rigel is the 7th brightest star in the night skies, and is a blue-white supergiant star.  It’s about 860 light years away.

Three significant stars form the belt of Orion. Going from right to left, they are Alnitak (740 light years away), Alnilam (2000 light years away), and Mintaka (690 light years away.)

The area adjacent to Alnitak contains both the Horsehead Nebula and the Flame Nebula.  Both of these Nebula are about 820 light years away, so they really don’t surround the star.


Now take the time to look at the middle star in the sword.  Does it look a little fuzzy?  The “fuzz” is caused by a huge bright nebula, M42, the Orion Nebula.  Don’t just look at the image of Orion that is borrowed from NASA - go Outside and take a look for yourself. If you have reasonably decent eyesight, on a clear, dark night you can see this nebula with your naked eye! Break out your binoculars to get a closer look at it. I recently used a pair of “birding” binoculars to view M42, and it is simply stunning!  And things only get better if you have access to a telescope…
This is a very quick shot I took of M42 in November.  M42 has a visual magnitude of  +4 and it’s over 1300 light years away.

Other things you can look for in December 2017

Saturn and Mercury will begin the month low in the sky near the Western horizon right after sunset.  You should be able to get a view of them for the first week of December.

Neptune, Uranus, and Pluto will be in the evening skies.  Uranus is the only one of the three you can see without a telescope or binoculars.  With a visual magnitude of 5.9, Uranus is pretty tough to find, but I actually did see it with my naked eye in November! I also got this image of it:

If you’re an early riser, you can see Venus, Jupiter and Mars in the Eastern pre-dawn skies.  Mercury will join them around December 20.  Mars will start the month rising at about 3:15 a.m. and Jupiter will follow at 4:35 a.m.  Venus won’t be visible until after 6:10 a.m., and will not be visible after December 12. 

The Geminid Meteor shower peaks the night of December 13.  You can expect as many as 120 meteors per hour with the chance of a fireball or two.  The action appears to start near the twin Gemini twin stars Castor and Pollux.  Look for this pair to appear near the Eastern horizon at about 8:00 p.m. With any luck, you will be able to watch this meteor shower all night long.

The Ursa Minorids peak on the night of December 22.  It is expected to generate about 10 shooting stars per hour.  It’s easy to find  - simply look for the North Star.

Moon Phases:
1st Quarter is the 26th
 Full Moon is the 3rd
 Last Quarter is the 10th
 New Moon is the 18th

(Gerry Lebing is a retired computer scientist with the U.S. Geological Survey in Washington, D.C.  He has visited Hatteras Island since the mid-1970s. He and his wife, Karen, have owned property here for several years and moved to their home in Waves full-time in 2013.  Astronomy is a subject that Gerry says he has always been interested in and one that he pursues seriously -- he's built an small observatory next to his house. You can send him questions about the night sky through e-mail, [email protected]g.)

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