The days are growing shorter in the northern hemisphere, which may not be the best for productive afternoons, but the extra darkness means some more time for looking up at the night sky. December ushers in winter for the northern half of the globe, which is a prime season for stargazing due to the added darkness and the cold air being less hazy than warmer, humid summer air.
Here are some celestial events to keep your eye on while closing out 2022.
December 7-Full cold moon
The last full moon of the year will reach its peak illumination at 11:08 pm EST on December 7. The Old Farmer’s Almanac recommends looking for it just before sunset as the moon begins to peek above the horizon. December’s full moon will will also be above the horizon for longer than most full moons, due to its higher trajectory in the sky.
December’s full moon is called the Cold Moon, or the “time of cold” moon, a Mohawk name that evokes when winter’s chill really grips the northern hemisphere. Some other names for the last full moon of the year are the Snow Moon (Eastern Band of Cherokees), the It’s a Long Night Moon (Oneida), and the Winter Maker Moon (Abenaki).
December 7-Mars at opposition
The same night as the last full moon of 2022, Mars will be in its brightest opposition. According to NASA, Mars and the sun are on directly opposite sides of Earth during opposition. From Earth, Mars rises in the east just as the sun sets in the west, and after staying up in the sky all night, Mars sets in the west just as the sun rises in the east. Astronomers say Mars is in “opposition” because the Red Planet and the sun appear on opposite sides of the sky. If Earth and Mars followed perfectly circular orbits instead of more oval shaped elliptical orbits, opposition would be as close as the two planets could get.
For the best chance to see the Red Planet in all its glory, face east about an hour after dark. Mars will look like reddish-orange star that will rise and appear more to the south as the evening wears on. By midnight, the planet will be high in the south.
December 13 and 14-Geminid meteor shower peaks
If shooting stars are more your thing, you won’t want to miss the Geminid meteor shower. It is one of the most reliable meteor showers every year and stargazers can see up to 120 meteors per hour at the shower’s peak if watching from a dark location, with an average of 75 space rocks per hour. The stellar show typically begins as early as 9 pm and peaks around 2 am.
[Related: How to photograph a meteor shower.]
This year, the Geminids will be competing with a bright waning gibbous moon, which might make it more difficult to see the shooting stars due to the extra light in the sky. The Old Farmer’s Almanac recommends trying to face away from the Moon to keep its shine out of your field of view.
On the evening of December 13, the moon will illuminate the sky from late evening on, but it will rise a little bit later on December 14.
December 21-Winter solstice (Northern Hemisphere)
Winter will officially begin on December 21, with the astronomical solstice and the shortest day of the year. The solstice officially occurs at 4:48 pm EST and is the day with the fewest hours of sunlight. After the winter solstice, the days will slowly grow longer as Earth inches towards the summer solstice in June.
Since the Earth is tilted on its axis, on the solstice, one half of planet is pointed away from the sun and the other half is pointed towards it. The solstice technically only lasts a moment, when a hemisphere-in this case, the northern-is tilted as far away from the sun as it can be.
[Related: Why we turn stars into constellations.]
The winter solstice is celebrated by cultures around the world with festivals, parties, and feasting due to its symbolism of light triumphing over darkness.
December 21 and 22-Ursid meteor shower peaks
In case you have to miss Geminid earlier in the month or the moonlight interferes with it too much, the Ursid meteor shower is predicted to peak on December 21 and early in the morning on December 22. Since the moon will be a faint waning crescent moon (only 3 percent illumination) it likely won’t interfere with this year’s Ursids in 2022.
Ursids can produce many as five to 10 meteors per hour, with a dark sky and little to no moonlight. Although, bursts of 100 or more meteors per hour have been observed.
December 21 and 24-Mercury at its greatest elongation and dichotomy
This will be the planet Mercury’s fourth evening apparition of the year. Its greatest elongation occurs when the planet appears to be farthest from the sun. Stargazers can even start looking for Mercury in the evening sky beginning in the second week of December. Mercury, the smallest planet in our solar system, can best be seen looking towards sunset as soon as the sky begins to darken. It will reach its greatest elongation on December 21 and will be 5 degrees away from Venus that night.
On December 24, Mercury will reach dichotomy, or an intermediate half phase, at about the same time that that it appears furthest from the sun. The exact times of the two events may differ by a few days, only because Mercury’s orbit is not quite perfectly aligned with the ecliptic.
The same rules apply to watch this meteor shower and lunar eclipse apply to pretty much all space-watching fun: go to a dark spot away from the lights of a city or town and let the eyes adjust to the darkness for about a half an hour. Happy stargazing!