Monthly Night Sky Report: December 2018

I can't believe that another month has already gone by and it's time for a new Monthly Night Sky Report.  This year has certainly flown by for me!  I look forward to this time of year for the beauty that the snow in Utah can bring and also the peacefulness.  Have you noticed that while it's snowing, it's quieter outside?  Unfortunately, the frequent snow storms that we receive and the below freezing temperatures hinders the amount of time that can be spent comfortably under the stars.  Nevertheless, I find myself often gazing upwards in hopes of catching a star, planet, or even the Moon, peeking through the clouds.

Like me, I'm sure many of you have noticed the return of Orion to the morning sky.  This constellation will rise earlier with each passing day, and will soon be noticeable shortly after sunset.  You may have also noticed the brightest star in the sky, Sirius, and if you have dark enough skies, you may be able to see the Pleiades.  As mentioned in a previous post, you can use the three stars of Orion's belt to find Sirius and the Pleiades.  In the northern hemisphere, if you trace out a line from the belt stars to the left, you will come to Sirius.  If you go to the right, you will find the Pleiades.  I think this group of stars looks like a tiny dipper (like the big and little dippers, only much smaller).  I challenge you to find the Pleiades this winter and let me know what you see!

Mercury

Mercury will still be found in the eastern sky before sunrise during December.  It will be slightly brighter than it was in November, shining at magnitude -0.4.  The highest Mercury will reach in our sky this month will be about 10° which occurs on the 15th, about 45 minutes before the Sun rises.  Two other planets meet up with Mercury in the morning sky this month, Venus, which rises before Mercury, and Jupiter, which will rise later.  Venus and Jupiter will be much easier to spot since they will shine more brightly.

Venus

Venus will continue to dominate the morning sky throughout December.  A few people have mentioned how spectacular this planet has been in the mornings, but I haven't had a chance to witness it myself until this morning.  It was quite a sight!  I had to keep looking at it to make sure it wasn't an aircraft with its landing lights on.  Venus will start the month off shining at magnitude -4.9 and will only dim slightly as the month wears on.  This planet will rise around 4 in the morning and will be visible for approximately 3 hours before the Sun rises.  Venus will be joined first by Mercury, and then followed by Jupiter.         

Mars

Mars will be found in the constellation of Aquarius during the first half of the month, which can be found in our southern sky after sunset.  The red glow from Mars will dominate the other stars in this region of sky and should be easy to spot with it glowing at magnitude 0.0.  If you are able to use a pair of binoculars to target Mars during the first week of December, you should be able to spot the  blue-gray disk of Neptune which will lie within your field of view.  For the second half of the month, Mars will slide from Aquarius into the constellation of Pisces the fish. 

Jupiter

Jupiter will join Mercury and Venus in the morning sky this month.  The closest approach Jupiter will make to Mercury in our skies will be on the morning of the 21st when the two lie less than 1° apart.  Jupiter will be easier to spot since it will shine more brightly at magnitude -1.8.  This giant planet will lie too low on the horizon to offer any surface detail, but you should still be able to spot the four largest moons with a pair of binoculars.  The views will improve in January when Jupiter will climb high enough in the morning sky before the Sun's brightness washes it from view.

Saturn

Saturn will only be visible for the first half December.  It can be found towards the southwest after sunset and will shine at magnitude 0.5.  Saturn will be joined by the Moon on the 8th at which time only 3° will separate the pair.  Saturn will join the current morning planets early next year, so keep a look out for its return. 

Uranus

Neptune

The outer ice giants will require a telescope for the best possible views from Earth.  As mentioned, Neptune will be found close to Mars during the first week or two of December.  The closest approach will occur on the evening of the 7th when the two planets are nearly on top of each other, from our view, of course.  Uranus will be much harder to find this month.  It will start the month off in the constellation of Aries the Ram, but by the 3rd it will have already moved to a new constellation, Pisces the Fish.  There aren't any bright stars in this region of the sky to help guide you to this planet, but you can always use a phone app to aid in locating Uranus, if desired. 

Meteor Shower

The Geminid Meteor Shower will peak on the night of the 13th/morning of the 14th.  The Moon will set around 11 on the 13th so it won't wash out any of the meteors after this time.  This is one of the best showers of the year, if you can stand to be out in the cold.  During the peak dates, viewers can witness up to 120 meteors per hour.  That's an average of 2 per minute!  These meteors will appear to radiate from the constellation of Gemini.  Gemini can be located towards the east after moonset, but by 1 in the morning, it can be found directly overhead.  It's best to not look directly at where they radiate from, but a few degrees away to catch the longest meteor trails.  If you are brave enough to take on the cold temperatures, let me know what you see!

Comet Watch

This month we will have a special visitor which might reach naked eye visibility.  Comet 46P/Wirtanen will make a close approach to the Earth, astronomically speaking, on the night of the 16th.  On this night, it will lie only 7.2 million miles away and will likely glow around 7.0 magnitude.  At this brightness, you will still need a pair of binoculars or larger instrument to see.  Some astronomers estimate that it may get as bright as 4.0 magnitude which you can see with the unaided eye if you have a dark enough sky.  Comet 46P/Wirtanen can be found in the constellation of Taurus the Bull, near the Pleiades and the star Aldebaran.  Those into astrophotography should try getting an image of this comet.  I know I will, as long as the sky is clear.  

Monthly Breakdown

December 01:  Venus at its greatest magnitude for the month (-4.9)
December 03:  Moon and Venus pass within 4°
December 05:  Moon and Mercury pass within 2°
December 07:  New Moon 🌑
December 07:  Mars and Neptune less than 1° apart
December 08:  Moon and Saturn pass within 1.5°
December 13/14:  Geminid Meteor Shower peak
December 14:  Moon and Neptune pass within 3°
December 15:  First Quarter Moon 🌓
December 16:  Comet 46P/Wirtanen closest approach
December 17:  Moon and Uranus pass within 5°
December 21:  Mercury and Jupiter pass within 1°
December 21:  Winter Solstice - shortest day of the year
December 22:  Full Moon 🌕
December 29:  Last Quarter Moon 🌗

Think About This....💡

I have another short topic for this section this month.  What I want to share with you, I saw on the Astronomy Picture of the Day website a couple of years ago and found it quite fascinating.  You will likely have to use a computer to view it since it's interactive and requires Adobe Flash Player to run it.

What I would like to share with you is the scale of the universe and all known things.  The largest, of course, is the universe, or at least the observable part that we have detected.  On the other end of the scale you have what is known as the Planck length.  I have studied this quite a bit in one of my classes this semester, but won't bore you with all of the details.  Pictures are more fun anyway!

Here is the link for the Scale of the Universe.  Enjoy!  

Now get outside and look up!

Planet images taken by NASA.

Andrew vs. the Cosmos taken by Jeff Greenland.