Monthly Sky Night Map
Look up! This sky map for December 2016 will help you navigate the stars and constellations in the night sky. On this page is both a color sky map and a black and white printable map to bring outside!
Four Rocks, the Cross, and the Swan
Few people ever see Mercury, the planet closest to the Sun. It never strays far from the Sun and thus is usually hidden in the glare of our star. Occasionally, the position of Mercury, the location of the Sun, and the hours of darkness all combine to allow us to glimpse this elusive planet. So it is this year in the second week of December.
Just ciick here or on the image below to open the printable map—then bring outside!
Scout around in the daytime for a location where your view toward the south-southwest is free from trees, buildings, and other obstructions. On the first clear night, go to your chosen observing location about 30 minutes after sunset, and look for a bright-ish starlike object low in the south-southwest. This is Mercury, and you are among the small minority of humans ever to see it!
Mercury’s location, so close to the Sun, makes it difficult to observe with Earthbound telescopes and tricky to reach with spacecraft. The Mariner 10 spacecraft flew past Mercury three times in 1974 and 1975. Then in 2011, the Messenger spacecraft was placed into orbit around Mercury, only the second spacecraft ever to explore the planet.
While searching for Mercury, you may be distracted by the bright blaze of the planet Venus to the upper left. Venus is the second planet from the Sun and comes closer to Earth than any other planet. Its proximity to us, along with a highly reflective covering of clouds, makes Venus appear brighter than any other planet from our viewpoint.
Venus has long been considered Earth’s “twin.” It is approximately the same size, has the same mass, and is made of the same types of materials as Earth. The big difference between the two planets is that Venus’s thick atmosphere, consisting largely of carbon dioxide, has a created a runaway greenhouse effect on the planet, raising the surface temperature to above 700°F.
Mars, the Red Planet
Also in view this December is Mars, the Red Planet and fourth from the Sun. Look to the upper left of Venus; Mars is the only bright object in the vicinity. Mercury, Venus, Earth, and Mars are known as the “rocky” planets. Compared to the outer “gas giant” planets (Jupiter, Saturn, Uranus, and Neptune), the rocky planets are small and have solid surfaces and interiors. Earth really is the “third rock from the Sun,” and you are standing on it!
Constellation Cygnus, the Swan
After observing three bright planetary dots, let’s look at something much larger, the glorious constellation Cygnus, the Swan. High in the sky, the brightest stars of Cygnus form the nearly perfect Northern Cross asterism. The bright star Deneb, 19th brightest in the sky, sits at the very top of the cross. The star Albireo is at the base. The Northern Cross is a beautiful sight in itself, but if your sky is dark enough, you may be able to see the entire Swan.
Additional stars are off the ends of the cross; these form the wings of Cygnus. With Deneb at its tail and Albireo forming the beak, the Swan is poised head down, swooping toward the ground.
Take a look! It’s yet another really big show!
December 2016 Sky Map
Click here or on image below to enlarge this map (PDF).
Sky map produced using Chris Marriott’s Skymap Pro
Enjoy astronomy? Check out Bob Berman’s column, “This Week’s Amazing Sky.”