Idaho Skies Newsletter for December 2016

December 1 – 7

The month opens with brilliant Venus visible in the Southwest. To the upper left of Venus is far less brilliant Mars shining in its pale yellow-orange light.

The thin crescent moon appears to the right of Venus on the evening of the 2^nd. The moon is only three days old that night, meaning earthshine should be easily visible, especially in binoculars.   

The moon continues its journey across the sky and passes close to Mars on the evening of the 4^th. Mars will be the pale orange-yellow star to the moon’s left. Mars will not show detail through binoculars, however, stargazers will see craters along the edge of the moon.

Neptune’s much easier to find on the night of the 6^th on account of the moon. The nearly first quarter moon is only 2 degrees away from the 8^th planet that night. To find Neptune, stargazers need to point their binoculars at the moon and then look a bright star just above and left of the moon. There are two fainter stars to the right of this star that form a line. The last star in that line is Neptune. You can confirm you’re looking at Neptune by the fact that Neptune will be brighter than the star in the middle, but not as bright as the star on the left end of the line. In addition, if you put the moon in the center left of your binoculars, then Neptune will be in the star located in the center right.  

Put down your binoculars and you’ll see there’s a bright star way below the moon. The star’s name is Fomalhaut. It belongs to the constellation of Piscis Austrinus, or the Southern Fish. It’s a relatively young star and only 25 light years away from the solar system.

The moon reaches the first quarter phase on the 7^th. This is a good time to take a gander at it through your binoculars or small telescope. Lots of craters will be visible along the terminator or boundary between day and night. However, most of the craters will be scattered across the moon’s southern hemisphere.   

December 8 – 14

The 7^th planet is just under 5 degrees from the moon on the 9^th. That means you can see it and the moon at the same time through your binoculars, but just barely. To find Uranus, point your binoculars at the moon and then shift them until the moon is located in the lower left edge of your field of view. Uranus will be the star in the upper right edge of the view. You can confirm its Uranus if it appears as the lower left corner of a triangle of stars. The star at the top of the triangle will be about twice as bright as Uranus.

Stargazers wanting to locate Aries the Ram will appreciate the moon on the 10^th. That night, the moon is located below the three brightest stars forming the constellation. The brightest star of Aries is named Hamal and it’s located on the left end of the constellation. 

Stargazers’ best view of Mercury this month is the evening of the 12^th. Mercury will appear low in the southwest horizon as its getting dark at 6:00 PM. The low altitude of Mercury means binoculars will be helpful to stargazers searching for the planet. Equally important is having a clear and low southwest horizon. Mercury is 4 degrees above the horizon, or just less than the width of a binoculars’ field of view above the horizon.

After it gets dark on the 12^th, point your binoculars at the moon. You’ll find it’s slowly drifting through the Hyades star cluster. The majority of the star cluster will be located above and to the upper right of the moon while Aldebaran, the brightest star in the Hyades, is located to the left. This makes an attractive sight for binoculars. Even better, the moon will occult, or cover up Aldebaran a little later.

The occultation of Aldebaran begins on the 12^th at 8:12 PM and ends at 9:11 PM. You’ll want to start watching a good five minutes before the disappearance of Aldebaran so that you won’t miss it. You’ll notice that the star quickly winks out when it’s covered by the moon. Its reappearance will be equally abrupt. Since the moon is still not full on the 12^th, the disappearance of Aldebaran will occur along the dark edge of the moon. The reappearance may be difficult to detect initially since it occurs on the illuminated hemisphere of the moon. So start watching the upper right edge of the moon before 9:10 PM to catch Aldebaran’s reappearance.  

 

For beginning new stargazers who are interested in learning to identify Orion the Hunter, your best opportunity this month is the 13^th. That night, the moon will be located above the constellation. Orion is the tall rectangle of stars below the moon. You’ll know you’re looking at Orion if you also see a row of three bright stars forming a horizontal line through the middle of the rectangle. These stars are nearly the same brightness and represent Orion’s Belt.

By the way, the moon is also full on the 13^th. The full moon in December is called the Cold Moon.

The moon passes through the feet of Gemini the Twins on the 14^th. The stars in Gemini form two horizontal rows of stars and the moon will be at the right end of the bottom row. That row represents Pollux, the mortal brother of the twins. Another way to picture Gemini is as the waist and legs of a soccer player. That makes the moon a soccer ball that Gemini is about to kick.  

 

December 15 – 21

The moon and Beehive star cluster are visible together in binoculars on the night of the 16^th. To see this very attractive star cluster, place the moon in the lower right edge of your binoculars. The Beehive star cluster will then appear at the upper left edge. Shift you binoculars to Beehive and get the moon out of view for better images of the star cluster. How many stars can you see in the Beehive?

If you go outside after midnight on the 19^th, you’ll find Leo the Lion sitting on top of the moon. Leo is an old constellation; it was one of the original 48 constellations recorded by the ancient astronomer Ptolemy in the 2^nd century AD. However, its history is ancient even for Ptolemy because the Mesopotamians recognized it as a lion 4,000 years earlier.

The moon is in the last quarter phase on the 20^th. Third quarter means stargazers will need to go outside after midnight to see it. They’ll be rewarded for their effort by the excellent views of its heavily cratered southern hemisphere that binoculars will show.

Winter begins on the morning of the 21^st. So welcome winter solstice. The word solstice means sun standing still and refers to the fact that the sun’s point of rising on the horizon doesn’t appear to shift north or south for several days. Normally, stargazers notice that the sun rises in a more northerly point during the winter and spring, and a more southerly point during the summer and fall. On the first day of winter that motion temporarily halts, hence the name, solstice.

December 22 – 31

Early risers will find a very bright star below the crescent moon on the morning of the 22^nd. The star won’t twinkle like other stars because it’s actually the planet Jupiter. The slightly fainter star below Jupiter is a real star and its name is Spica. Spica is the brightest star of Virgo the Maiden. Finally, earthshine or the faint illumination on the dark portion of the moon may also be visible that morning. A pair of binoculars will come in handy for seeing it. You’ll find the moon in the low southeast on the morning of the 22^nd.   

The moon, Jupiter, and Spica form a trio on the morning of the 23^rd. Earthshine should be easier to see that morning than it was a day ago. You’ll need to go outside after 4:30 AM and before 7:00 AM when the light of dawn will begin washing out the stars in the east.

Zubenelgenubi is a double star that appears as a single star to most people. Stargazers with binoculars won’t be tricked however. You can find this double star for yourself on the morning of the 24^th. It’s made easy because Zubenelgenubi is the star below the crescent moon at 6:00 AM. The moon and Zubenelgenubi are so close enough together that they can be seen at the same time in binoculars (just barely). In binoculars, you’ll see that Zubenelgenubi is really two stars next to each another.

Did you get a telescope on Christmas Eve or Christmas morning? Then point it at the very thin crescent moon at 6:00 AM on the 25^th. You’ll see earthshine illuminating the dark portion of the moon and craters nearly edge-on.

It’ll be a little tough, but stargazers can see a very thin crescent moon on the morning of the 26^th. Look very low in the southeast at 7:00 AM to glimpse the moon in the light of dawn.     

The moon is new late on the 28^th, so you might be able to see it when it reappears on the 30^th in the evening sky. The moon will be two days old, which is younger than most people have seen it without making a serious effort. To see the moon, scan the southwest horizon at around 6:30 PM. The moon is located to the lower right of brilliant Venus.

If you can’t find the moon on the 30^th, then try again on the 31^st. The moon will appear higher above the southwest horizon at 7:00 PM. The sky is darker, making the moon easier to see than it was at 6:30 PM a day earlier. 

Mars passes 1/12^th of a degree from Neptune on the night of the 31^st. So point your binoculars at Mars, which appears as the yellow-orange star in the low west-southwest. Once you center Mars in your binoculars, Neptune will be the faint star straight up and slightly left of Mars. Since they’re only 1/12^th of a degree apart, the distance between Mars and Neptune are only 60^th of the way across your binocular field of view. So we’re talking about them being very close together.     

This Month’s Sources

Astronomical Phenomena of the Year 2016, The Nautical Almanac Office and Her Majesty’s Nautical Almanac Office

Astronomy Calendar of Celestial Events for Calendar Year 2016, http://www.seasky.org/astronomy/astronomy-calender-2016.html 

Night Sky Explorer

Dark Skies and Bright Stars,

Your Interstellar Guide