Venus and Mercury are evening objects and hard to see as the month starts. Observers close to the equator and in the low southern latitudes have the best view of Mercury pulling up higher than Venus alongside the stars of Sagittarius. Mercury is close to Kaus Borealis (the northern bow star) on the evening of the 10th. Venus passes the star on the 14th as Mercury goes by Nunki. Mercury reaches greatest elongation on the 21st having made it 20.1° into the evening sky. A thin crescent moon will be near the two planets on the 24th. Mercury’s turning around and Venus is catching up to it. The two planets are 1.4° apart on the 29th.
Saturn moves slowly and directly among the eastern stars of Capricornus this month, well above Mercury and Venus in the west. It’s chose to Nashira by month’s end. A crescent moon passes them on the 26th.
A slightly gibbous and waxing moon is by Jupiter as December begins. The big planet is another slow direct mover this month. It’s near Pisces and above Diphda, a star in Cetus. See them close to the meridian at sunset. The moon’s at first quarter as it passes by Jupiter on the 28th and 29th.
In the east at sunset, Mars is a third of the way from Elnath to Aldebaran. The red planet is retrograde and heading toward the Pleiades. It won’t make it all the way to the cluster before it turns around next month. Much of North America and Europe get a splendid view of the full moon hiding Mars as the planet’s at opposition. The event is on the evening of the 7th in the westernmost visibility zone and on the morning of the 8th in the easternmost parts. The moon’s disk will cover the red planet for an hour or more for observers deepest in the zone. To the naked eye, the planet will dim until it disappears over the course of a minute and then brighten up as it reappears on the other side of the lunar disk. In a telescope, many viewers could see an ice cloud around the northern Martian pole.
Orion and Gemini are fine sights rising in early evening. Leo rises late evening. The moon passes through Leo just before it’s at last quarter in Virgo on the 16th. See the waning thick crescent close to Spica on the morning of the 18th.
The Geminid meteors are expected to peak around the 14th. The shower is associated with an asteroid that many scientists think was a comet nucleus. There’s no comet dust left give it the normal comet look with a coma or tail as it goes close to the sun. But the asteroid itself, and not long lost comet dust, may be the source of the meteors. This shower wasn’t known until the 1800’s and radar studies of the particles show they are dense like rocks.
Earth’s solstice is on the 21st at 21:49 UT. Mars has its northward equinox on the 26th. Venus is at aphelion the same day.
Moon information for this month: Full on the 8th, last quarter on the 16th, new on the 23rd, and first quarter on the 30th. Apogee at 405,900 km is on the 12th. Perigee at 358,300 km is on the 24th. The moon goes north of the equator on the 2nd. It’s at northern lunistice 27.4° from the equator on the 9th. It goes south again on the 17th. Southern lunistice at 27.4° is on the 23rd. And it goes north of the equator again on the 29th.