Mars is the only prominent planet in December’s night sky, in the constellation Aquarius. Neptune is close to Mars, but near the limit of naked-eye visibility, as is Uranus in the adjacent constellation to the east, Pisces.
Mars, the first quarter moon and Neptune form an equilateral triangle within the field of a pair of 7 x 50 binoculars on Dec. 14. If you position Mars at about 10 o’clock, and the moon right out of the field at 7 o’clock (so as not to overwhelm your vision with its brilliance), you will see Neptune at about 4 o’clock.
Venus shines brightly in the morning, near the brightest star in Virgo, Spica. On Dec. 3 and 4, the thin sliver of the waning crescent moon lies within a few degrees of the planet.
On Christmas night, the nearly full moon sits right in the Beehive, the splendid open cluster in the middle of Cancer. Known in Latin as "Praesepe," meaning crib or manger, the cluster contains over 1,000 stars, 577 light-years away. In the 1700s, French comet hunter Charles Messier compiled a list of about 100 fuzzy or diffuse objects that could be confused with comets. Now known as the Messier Catalog, it includes the most magnificent objects in the heavens, with Praesepe known as M44.
Comet Wirtanan is presently the brightest comet in the night sky, yet remains below naked-eye visibility. It may brighten up as it nears the sun late in December.
The Geminid meteor shower peaks on Dec. 14 with the greatest number of meteors falling after midnight, when the radiant point — the constellation Gemini — is highest in the sky. The higher the radiant point climbs into the sky, the more meteors you’re likely to see. On a clear, dark night, you can often catch 50 or more Geminids an hour. The moon sets around midnight that night, and will not interfere with viewing the shower.
The winter solstice occurs on Dec. 21, and is the moment in time when the Earth's tilt away from the sun is at its maximum, and the sun's maximum elevation in the sky is at its lowest.
Q: How many stars are in our galaxy? — Naomi A., Canton
A: While there is no simple way to count the stars in our galaxy, one can find many estimates. Thumbing through a couple of astronomy books in my office, one written in 1959 says there are about 30 billion, another written in 1972 says 100 billion. Some internet sites suggest trillions.
Recently NASA has made most likely the most accurate estimate based upon the calculated mass of the galaxy and the percentage of that mass that is made up of stars. (Neither of these calculations is simple.) Their estimate is that the Milky Way contains between 100 and 400 billion stars. The same methodology gives an estimate of about 1 billion trillion stars in the observable universe.
The periodically updated "The Universe at Large" is presented at 1 p.m. Saturdays and 2 p.m. Sundays at the Hoover-Price Planetarium. It is included with admission to the museum. Children must be 5 years or older to attend.
The planetarium also offers an astronomy program for adults only on the first Monday of every month at 1 p.m., with a show followed by a 30- to 45-minute open lecture/discussion.
For more information visit the planetarium’s blog on the museum’s website, or call 330-455-7043.
David L. Richards is director of the Hoover-Price Planetarium at the McKinley Presidential Library and Museum, 800 McKinley Monument Drive NW, Canton, www.mckinleymuseum.org. He can be reached at 330-455-7043, email firstname.lastname@example.org or read his blog at https://hooverpriceplanetarium.wordpress.com/.