December full moon mimics the June sun

Star chart with moon, Mars, Aldebaran, Pleiades and Orion all labeled, also ecliptic line.
In 2022, the December full moon on the 7th – aka the Cold Moon – can be found near a triangle of noteworthy objects: the dipper-shaped Pleiades star cluster, the fiery red star Aldebaran (Eye of the Bull in Taurus) and bright red Mars, now at opposition to Earth. The moon will pass in front of Mars on this night. Read more about the occultation. Chart via John Jardine Goss/ EarthSky.

The last full moon of 2022 will come on the night of December 7-8. For us in the Northern Hemisphere, it’ll cross high overhead. Meanwhile, from the Southern Hemisphere, it’ll ride low in the sky. Why? Because a full moon is always opposite the sun. And – for us in the north now – the sun rides low (so the moon rides high). For the Southern Hemisphere, the sun rides high (so the moon rides low).

The December full moon will fall at 04:08 UTC on December 8, 2022 (10:08 p.m. CST on December 7). That’s the moment when this month’s moon is most directly opposite the sun as seen from Earth. It’ll be an eventful night for this full moon. Mars will reach opposition on this night. In other words, Mars is also opposite the sun on the night of December 7-8. Since both the moon and Mars are opposite the sun, it’s no surprise that these two worlds appear near each other. From some parts of Earth, the moon will occult Mars – pass in front of it – on the night of December 7-8.

Read: Mars in 2022, at opposition December 7-8

Read: Moon will occult (cover) Mars on December 7-8

Available now! 2023 EarthSky lunar calendar. A unique and beautiful poster-sized calendar showing phases of the moon every night of the year! Makes a great gift.

December full moon mimics the June sun

Every full moon is more or less opposite the sun. And a full moon’s path through the night is opposite the sun’s path. So this December full moon’s path roughly follows the sun’s daytime path from six months ago, or six months from now. No matter where you are on Earth, notice the moon’s path on December 7-8. The Northern Hemisphere will see the December full moon rise to nearly the top of the sky, just as the sun does near the June solstice. The Southern Hemisphere will see a low moon, mimicking a low winter sun.

Here’s another way to look at it. In the Northern Hemisphere, the December solstice has the least amount of daylight of the year. Since there’s still about 24 hours in a day no matter how much daylight there is, the shortest day means it must also be the longest night. In order for the moon to stay up all night and remain roughly opposite the sun, it needs to take a longer path across the sky. The higher an object crosses the sky, the longer its path and the longer it stays above the horizon.

Names for the December full moon

Do you see why tonight’s moon is sometimes called the Long Night Moon?

But – like all full moons – the full moon of December has many nicknames: Long Night Moon, Full Cold Moon, Moon Before Yule. But no matter which name appeals to you, be sure to notice the moon’s high (or low) path!

December full moon: Diagram showing the full moon lies opposite the sun.
At full moon, the sun, Earth, and moon align in space, with Earth in the middle. The moon’s day side – its fully lighted hemisphere – directly faces us. Chart via John Jardine Goss/ EarthSky.

Tracing the high path of the December full moon

Try this. Trace a line with your finger from east to west to emulate the sun’s path in December. If you’re in the Northern Hemisphere, you’ll be tracing a low arc above the southern horizon. Then, with your finger, trace another path high overhead. Now you’re emulating the moon’s December path, and you’ll see it’s a longer path than the lower one.

Little by little, we can watch the two paths come back into balance. Each month, the full moon will cross the sky at a slightly lower arc than the previous month. Each successive full moon will take less time than the previous one to cross the sky.

Parallel dashed-line arcs of the moon's path, one high for December, one low for June.
The December full moon arcs high across the sky, while the June full moon arcs low. The December full moon closely follows the arc of the June sun. Chart via John Jardine Goss/ EarthSky.
Parallel dashed-line arcs of the sun's path, one high for June, one low for December.
The December sun arcs low across the sky, while the June sun arcs high. The December sun closely follows the arc of the June full moon. Chart via John Jardine Goss/ EarthSky.

What about an equinox moon?

At March’s full moon, which is near the Northern Hemisphere’s spring equinox, the two paths – of the moon and of the sun – will be nearly the same. Then, near the June solstice, those of us in the Northern Hemisphere will see the sun cross high overhead during the year’s longest days. And, during the short northern summer nights, we’ll see the moon cross lower and spend less time in the sky.

And on the cycle goes.

Last full moon of 2022

This full moon is the last full moon of the Northern Hemisphere’s autumn – and Southern Hemisphere’s springtime – and it’s also the last full moon of 2022.

Plus it is the closest full moon this year to the December solstice, occurring just 13 days before the solstice. This solstice marks the start of winter in the Northern Hemisphere (and summer in the Southern Hemisphere). It falls on December 21. The January 2023 full moon is 16 days after this December solstice.

You’ll find this December 2022 full moon in Taurus the Bull, as shown on the chart below.

Enjoy December’s full moon! And don’t forget … the red object near it is Mars!

Complex chart showing apparent position of moon among constellationns.
The December full moon lies opposite the sun in the constellation Taurus the Bull. Chart via John Jardine Goss/ EarthSky.

Bottom line: The 2022 December full moon happens overnight on December 7-8, 2022. It closely follows the path of the June sun. It’ll be near bright red Mars. And from some places it’ll occult or pass in front of Mars.

Read: Mars in 2022, at opposition December 7-8

Read: Moon will occult (cover) Mars on December 7-8

December 6, 2022

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