Your Local Time:





Planetarium Learning Center


YCAS Schedule

Public Observing




Tonight's Sky

Mason Dixon Star Party

New Telescope Users Help

Members Websites


Astronomy Classes

Offsite Events

Press Release

Star Child

Lunar Eclipse

Star Party and Astronomy Links




The December Night Sky

The sky is not a painting, it's a movie. Stars pulse, flare, some explode as supernova, asteroids whiz by the earth, new comets appear in the sky, Aurora sets the northern skies ablaze and meteors streak through Earth's atmosphere.

 Astronomy Picture of the Day

See below Hubble site Tonight's Sky, highlights of this months night sky movie with narration below. Click on photo below.

Winter Begins

The Winter Solstice occurs at 6:03 pm EST on December 21. The Sun reaches its southernmost celestial latitude of the year. On this day the shortest period of daylight begins in the Northern hemisphere. Summer begins in the Southern hemisphere.

The Full Moon for December

 December is known as the The Full Cold Moon; or the Full Long Nights Moon. December nights are at their longest and darkest. This full Moon is also known as the Moon before Yule. The midwinter full Moon has a high trajectory across the sky because it is opposite a low Sun.

Lunar Phases

Full Moon December 6 7:27 am EST
Last Quarter Moon December 14 7:51 am EST
New Moon December 21 8:36 pm EST
First Quarter Moon December 28 1:31 pm EST

December  Lunar Highlights

 On December 11th, Jupiter lies about 6° to the upper left of the gibbous Moon On December 19th Saturn lies just 3° below the narrow crescent Moon as both rise on the 19th. On December 24th the crescent Moon passes within an Angular separation: 06°degrees from Mars.

The Planets Visibility for December


Evening sky SW Currently lost in Suns glare.

Mercury is lost in the Suns glare until late December when it becomes a bit easier to see. In early January Venus and Mercury come closer together in the evening sky.


Evening sky SW

 Venus early December is just beginning to emerge from the Sun's glare. Venus by late December is an easy object to see in the south western horizon shining at -3.9 magnitude in the constellation Sagittarius.


Evening sky SW

Mars midmonth is at +1.1 magnitude and a diameter of 00'.05" located in the constellation Capricornus and sets at 8:09 p.m.. To find Mars look for a reddish object low in the southwest sky. On December 24th the crescent Moon passes within an Angular separation: 06°30'44"  from Mars. On December 24th a faint comet 15P/Finlay is only Angular separation of 00°11'16" from Mars. A large telescope is needed to see the faint 12.5 magnitude comet.

To see which part of the surface is visible at any time, check out the Mars Profiler at Sky & Telescope Magazine's web page.


 Evening - Morning sky SW

Early December Jupiter is at -2.4 magnitude and a diameter of 00'.43" located in the constellation Leo the Lion. Jupiter rises in the east around 9:51 p.m. on December 6th. Jupiter  on December 11th is an Angular separation of 05°44'39" from the 71.69 % phase gibbous moon.

A small telescope will easily reveal four of Jupiter's largest and brightest moons. Check out Sky & Telescope's Jupiter Moons Utility for other configurations. Sky and Telescope Red Spot Calculator  


  Morning sky ESE

Saturn is just emerging from the Suns glare and rises around 5:30 very low in the ESE morning sky just before sunrise. Saturn is at +0.5 magnitude and diameter 00'.15". Saturn is in the constellation Libra. On the 19th of December the crescent new Moon at 8.32% lit and Saturn are visible in the morning sky just before dawn as shown below.

Through a small telescope Saturn will reveal the famous rings of the planet. Rings currently are 22.7 tilt. See: Saturn's moons locations


Evening Sky SW

 Uranus midmonth is at 5.8 magnitude and diameter 00'.04" and is up in the southern sky after sunset setting at 1:36 a.m. midmonth. Uranus is located in the constellation Pisces. A moderate-sized telescope will show it as a green-gray disk. See: Sky and Telescope location PDF. Courtesy: Sky and Telescope


Evening Sky S

Neptune midmonth is at 7.9 magnitude and diameter 00'.02" is up after sunset visible in the south and sets 10:21 p.m.. A moderate-sized telescope will show it as a blue green disk. Neptune is located in the constellation Aquarius. See: Sky and Telescope location PDF. Courtesy: Sky and Telescope

Bright Asteroids


Dwarf Planets


 Pluto at midmonth is visible in the southwest right after sunset very low on the horizon and is amid the stars of the Milky Way in the constellation Sagittarius. Pluto is at magnitude +14.2 and diameter 00'.01"  A large telescope is needed to see this distant object.


Comets Brighter than 8 Magnitude

No bright comets visible for northern hemisphere.

For more on current Comets and locations see: Seiichi Yoshida web site here.


The Geminids

The Geminid meteor shower peaks on the night of Saturday evening/Sunday morning on December 13/14th, when meteor rates can be 60-120 meteors per hour. Best time to observe meteors is around 2:00 a.m. when the radiant is highest in the sky but can be seen as early as around 8:00 p.m. onwards till the meteors become lost in dawns light. Geminid meteor activity begins December 4th thru December 18th. The 53% lit Moon  rises during the second half of the night around midnight on the night of the peak and will diminish seeing the fainter meteors. Dress warm and enjoy the meteor shower all night long. The source for the Geminids is the asteroid 3200 Phaethon. See radiant for Geminids below. The yellow circle and meteor lines indicates the radiant where direction of meteors will appear from.

The Ursid Meteors

The Ursid meteors peak on the 22/23nd with around 10 meteors per hour. This meteor shower is active during the period spanning December 17 to 25. The shower occurs under favorable moonlight conditions. The comet 8P/Tuttle is the source for this meteor shower.

See: Listen to Meteors , American Meteor Society, Meteors Online also NASA All Sky Network

Some local links below to Heavens Above satellite information website.

Satellites Visible from York

Satellites visible from Hanover

Satellites visible from Gettysburg

Satellites visible from Lancaster

Satellites visible from Baltimore

Satellites visible from Harrisburg

Also see: Spaceflight NASA

 The Sun

Real time solar wind dials are linked live to the ACE Spacecraft.

 If the dial on the left (Magnetic Field) has dipped below zero, the speed is high and the dial dynamic pressure is in the yellow/red, be alert for Aurora. Anytime the gauges are in the Red and the dial on the left, the Magnetic Field BZ has dipped to the yellow-red... Aurora will be occurring in our area. See link to solar wind gauge here: REAL TIME SOLAR WIND

See explanation of  solar wind dials below by clicking on photo of dials

Solar Wind Dials


Use your hand to find degrees

NASA Night Sky Network Planner

Free download. AstroPlanner  

Download a free starmap at: Skymaps

Make your own starmap at: Star Finder

Download a free Planetarium for your computer at: Stellarium or Hallo Northern Sky Stellarium has many extra features.

Your Sky - Fourmilab

Your night sky map on the internet

Sky & Telescope Interactive Sky Chart Register to use.

Sky Map