Five planetary conjunctions with the Moon will occur this December. Read this article to learn how to observe them in the sky.
December 3: Moon-Mars conjunction
On December 3, 2021, at 00:27 GMT, the Moon will pass very close to Mars in the sky; both objects will be located in the constellation Libra. The angular distance between the two celestial bodies will be 0°41' — that’s only a little more than the Moon’s angular diameter!
Unfortunately, our natural satellite will be nearing its new phase: this means it will occupy the same region of the sky as the Sun, so it will be impossible to see the Moon at night. Consequently, Mars will also stay below the horizon all night — the only time you can observe the 1.6 magnitude Red Planet is just before sunrise. As Mars will be positioned close to the Sun, better not use a telescope for its observation to avoid eye injury.
December 7: Moon-Venus conjunction
On December 7, at 00:49 GMT, the thin crescent of the Moon will meet Venus in the sky. Our natural satellite will pass 1°52' to the south of the planet. The Moon, glowing with earthshine, will have a magnitude of -10.4, while Venus will be shining with a magnitude of -4.7. Look for this spectacular duo in the constellation Sagittarius.
At the beginning of December, Venus reaches its greatest brightness, so it’s the best time to observe the planet. If you have binoculars, try viewing Venus through them: the planet will look as a tiny thin crescent.
December 8: Moon-Saturn conjunction
On December 8, 2021, at 01:49 GMT, the conjunction of the waxing Moon and the ringed planet Saturn will occur. Our natural satellite will pass 4°11' to the south of the gas giant. The Moon will be at a magnitude of -11.0, and Saturn — at a magnitude of 0.5. Both celestial bodies will be positioned in the constellation Capricornus.
December 9: Moon-Jupiter conjunction
On December 9, 2021, at 06:10 GMT, the Moon will get close to another gas giant, Jupiter, passing 4°28' to the planet’s south. The Moon will be shining at a magnitude of -11.5, and Jupiter will have a magnitude of -2.3. Look for the two objects in the constellation Capricornus.
The Moon’s conjunctions with Venus, Saturn, and Jupiter will be especially spectacular because of the perfect planetary alignment: throughout December, the three planets will be lined up in a beautiful straight row along the ecliptic.
December 31: Moon-Mars conjunction
The month will end as it began — with the conjunction of the Moon and Mars. On December 31, 2021, at 20:13 GMT, our natural satellite will pass 0°56' to the south of the Red Planet; both celestial bodies will be located in the constellation Ophiuchus. Again, the Moon will be nearing its new phase, so both objects will be unobservable all night. You can try to spot 1.5 magnitude Mars sitting low above the horizon just before sunrise.
Note that observing conjunctions doesn’t require any special equipment — such events are easily visible to the naked eye. Also, don’t get disappointed if you miss the exact moment of conjunction; even the night after the conjunction, the two objects you’d like to see will still be positioned quite close to each other.