The coming month brings back-to-back meteor showers, the moon posing with planets, and plenty more reasons to look up at the night sky. You’ll even have the chance to catch meteors paired with the final supermoon of 2016.
So dust off those binoculars and mark your December calendar!
Moon and Venus—December 3
About a half hour to an hour after local sunset, the waxing crescent moon will dominate the southwest sky. A bright white “evening star, which is actually the planet Venus, will shine about seven degrees below the moon, making for a stunning pairing easily visible with the unaided eye.
Moon and Mars—December 4
At dusk the moon will position itself to the right of ruddy Mars. The two objects will be less than three degrees apart, equal to about six lunar disks. The red planet currently sits 117 million miles from Earth, which means that light and radio signals take nearly 11 minutes to travel one way between our worlds.
Supermoon and Aldebaran—December 12
At 1:25 p.m. ET (18:27 UTC) on the 12th, the nearly full moon—or what astronomers call the waxing gibbous moon—will reach its closest point to Earth in its monthly cycle, at a distance of only 222,738 miles. The coincidence of a full moon and the lunar orb’s closest approach is popularly dubbed a supermoon, and December’s event will be the third in as many months.
The moon will officially reach its full phase just a little over day later, at 2:06 p.m. ET (19:06 UTC) on December 13. Either night, it will be worth taking a look at the silvery orb rising in the east around the time of local sunset.
Meanwhile, try using binoculars or telescopes to spot the bright orange star Aldebaran near the moon. For lucky sky-watchers across most of North America and Western Europe, the red giant star, part of the constellation Taurus, the bull, will get briefly eclipsed by the moon at 11:13 p.m. ET (4:05 UTC).
Geminid Meteor Shower—December 13
The annual Geminid shower will reach its peak activity this night for viewers in the Americas. The Geminids are known to be quite prolific, with rates as high as 60 to 120 shooting stars an hour at peak times. Views of the meteor shower are expected to be good on the nights before and after the peak.
While sky-watchers will have to contend with the blinding glare of the supermoon, the brightest shooting stars should still be visible and will add to the spectacle. Stay tuned for our detailed viewer’s guide on how to get the best out of this unique sky show.
Moon and Beehive—December 16
As a great observing challenge, look for the waning gibbous moon to point the way to the famous Beehive open star cluster in the constellation Cancer, the crab. This beautiful group of stars lies about 610 light-years from Earth and was first mentioned back in 260 B.C. by ancient Greek poet Aratos, who referred to it as the Little Mist. The cluster is visible as a faint and tiny fuzzy patch to the naked eye under dark skies, and suburban sky-watchers can also hunt it down easily using either binoculars or small telescopes.
December Solstice—December 21
At 5:44 a.m. ET (10:44 UTC) on the 21st, the sun will be at its lowest point in the sky, making it the shortest day of the year north of the Equator. In the Southern Hemisphere, the sun will be at its highest point, making December 21 the longest day of the year for points south.
Seasons (and solstices) happen because Earth is tilted on its axis at it orbits the sun. During winter, the axis is slightly tilted away from the sun, so the hemisphere in question receives less sunlight. The exact date and time of the December solstice changes slightly from year to year because of the difference between a calendar year of 365 days and the solar year of 365.26 days—the exact time it takes for Earth to make one trip around the sun.
Ursid Meteor Shower—December 22
In the predawn hours of December 22, North Americans will see the peak of a minor annual meteor known as the Ursa Minorids, or the Ursids. As with all meteor showers, the Ursids are named after the constellation they appear to radiate from in the sky, in this case Ursa Minor, the little bear. These meteors appear to shoot out from a region of the sky just above the bowl of the Little Dipper, the well-known star pattern that’s part of Ursa Minor.
While the Ursids only produce an average of 10 to 15 shooting stars an hour, on rare occasions viewers will catch bursts of 30 or more an hour. This year, meteor watchers will have to contend with a waning gibbous moon, which rises the night before at around 1 a.m. local time, so expect to see much more modest numbers than usual, somewhere around five to 10 meteors an hour.
Moon and Jupiter—December 22
Early risers on the 22nd should see the waning crescent moon pose with brilliant Jupiter. While the moon will be a mere 254,000 miles away, Jupiter sits at a stately distance of 584 million miles from Earth. That’s so far that light takes 52 minutes to make the voyage from the gas giant to our planet.
Adding to the celestial beauty, the brightest star in the constellation, Virgo, will form an eye-catching straight alignment that will stretch nearly 10 degrees long, or about as wide as your fist held at arm’s length.
For these and more celestial events, check out my Starstruck column at National Geographic.