Current Night Sky: December 2018

The December Solstice occurs at 5:23 pm EST on December 21. The Sun reaches its southernmost celestial latitude of the year; this day brings the year’s shortest period of daylight in the Northern Hemisphere and the longest in the Southern Hemisphere. By convention, winter officially begins in the North and summer begins in the South.

The Moon & Planets: 
Mars and Neptune sky chart

On the evening of December 7, Mars and Neptune make an exceptionally close pairing. The two planets will be visible in the same field of view, even at high magnification. (The yellow circle in the chart above is 3 arc-minutes in diameter - one-tenth of the diameter of the Full Moon!). Mars presents a disk 8.8 arc-seconds wide; Neptune is just 2.3 arc-seconds across. Though the two planets appear close in the sky, they are at vastly different distances. Mars is 98 million miles away, while Neptune is 2.7 billion miles distant (December 7, 2018; 10:00 pm EST).

Geminid meteors

In the early morning hours of December 14, the Moon will have set, and the Geminid meteors take the stage. Their trails can appear anywhere in the sky, but they all point back to their "radiant" in the constellation Gemini. The meteor shower is spread across several nights, but peaks on the 14th-15th. Away from urban lights, you may see 120 meteors per hour (December 14, 2018; 1:30 am EST).

At mid-month, comet 46P Wirtanen may become bright enough to see with the naked eye. As it slowly moves against the background stars, it passes close to familiar sights such as the Pleiades (December 16, 2018; 10:30 pm EST).

Evening Planets (after sunset): 
  • Saturn, SW
  • Mars, S
  • Neptune, S
  • Uranus, SE
Morning Planets (before sunrise): 
  • Venus, SE
  • Mercury, SE
  • Jupiter, SE
Comets: 

Comet 46P Wirtanen reaches its closest distance from the Sun on December 13, and makes a close approach to Earth (7.2 million miles, or 29 lunar-distances) on the 16th. As with all comets, brightness projections are unreliable; however, some estimates place the comet becoming as bright as magnitude 4. This would make it a "naked-eye comet," visible to observers under dark skies.

Meteors: 

The Geminid meteor shower peaks on December 14/15. After the waxing crescent Moon sets around midnight, you may see up to 120 meteors per hour under dark skies.

Phases of the Moon: 
New Moon December 7 2:20 am EST
First Quarter Moon December 15 6:49 am EST
Full Moon December 22 12:49 pm EST
Last Quarter Moon December 29 4:34 am EST

Text, graphics, and animations by John Sheff. Graphics courtesy of Starry Night(©) Pro Plus 7 / Imaginova(©) Corp. Starry Night images are used with permission from Imaginova Corp. Starry Night is a registered trademark of Imaginova Corp. Star charts generated by Starry Night Pro Plus 7 © Imaginova Corp. All rights reserved. www.StarryNight.com