fluffy-looking pink and yellow nebula

Minnesota Skies: December 2020

Your local guide to observing celestial objects and events

Published11/30/2020 , by Thaddeus LaCoursiere and Deane Morrison

This year December belongs to Jupiter and Saturn. The two giant planets put on a show just before they drop over the horizon, on their way to the morning sky.

And what a show it is. On December 21, Jupiter and Saturn make their closest approach since 1623. Jupiter, with its higher orbital speed, glides just 0.1 degrees—about one-fifth of a Moon width—below Saturn. Because this happens in early morning, when Jupiter and Saturn aren’t visible, the evening of either December 20 or 21 will be the best time to look. The two planets will be so close that through a small telescope they, along with many of their moons, will fit into a single field of view.

Jupiter regularly overtakes Saturn like this; on average, it passes the ringed planet every 19.6 years. But they won’t get this close again until 2080. To see them, go out as soon as the sky darkens enough to reveal two orbs, one (Jupiter) much brighter, very low in the southwest. Try following the planets’ approach and separation over several days; say, from December 16–23. On December 16, a very young, thin crescent Moon comes out below them, making a pretty trio.

If you have neither a small telescope nor a good friend with one, try binoculars, especially if you can steady them with a tripod. If all else fails, images of the event are sure to pop up online.

Winter arrives officially with the solstice, at 4:02 am on December 21. At that moment the Sun reaches a point over the Tropic of Capricorn and begins its annual trek back toward the northern sky. However, although the day length shortens as we approach the solstice, Minnesotans experience the earliest sunset of the year during the first two weeks in December (the date varies slightly with location). After the solstice, our sunrises will still be getting later for several days, but the evening darkness will have begun to shrink.

December’s full Moon comes at 9:28 pm on December 29. It rises in late afternoon, opposite a sinking Sun.

December Sky-Lights

Orion Nebula

Throughout December
Located a few finger widths below Orion’s Belt is the beautiful Orion Nebula (M42). This glowing cloud of gas and dust (see the blog’s header image) is home to thousands of newborn stars and is a must-see for stargazers young and old, amateur and professional. Find Orion rising to the southeast as the Sun sets, and visible in the sky until the sun rises.

The Pleiades

Throughout December
Riding on the back of Taurus, the Bull, you can find the Pleiades (M45) visible throughout the night starting high in the sky to the south-southeast as the Sun sets. This open cluster is a mere 70 million years old and although the unaided eye can only spot six bright stars, binoculars or a telescope will reveal thousands more that make up this grouping. See if you can recognize a well-known car logo in the pattern of bright stars!

Geminids Meteor Shower

December 4–17
This shower peaks around the night of December 14, so head out whenever you can in the nights before and after to catch a glimpse of this yearly wonder. Meteors can appear from anywhere in the sky, so dress warmly and just look up!

Conjunction of Jupiter and Saturn

December 21
The two bright planets will appear within 0.1 degrees of each other, one-fifth the size of the full Moon! The last conjunction happened in 2000, but the planets haven’t been this close together since 1623! They will look like a bright single point of light to the eye, and will be easily seen with binoculars or a telescope. Look to the west just after sunset for this rare occurrence.

Winter Solstice

December 21
The December solstice occurs at 4:02 am. The North Pole of the Earth will be tilted as far away from the Sun as it gets throughout the year, giving us the longest day and marking the first day of winter in the northern hemisphere (and the first day of summer in the southern hemisphere).