Our charts fall during the narrow window of the night when no bright planets are visible. Instead, our eyes are drawn to the ESE where Orion stands clear of the horizon. His Belt points down to where Sirius rises within the hour and up towards Taurus and the star Aldebaran which stands close to the almost-full Moon on the night of the 5th.
North-east (above-left) of Orion is Gemini, the source of the year’s richest meteor display. The Geminids shower is active from the 8th to the 17th and reaches a peak over the 24 hours around 07:00 on the 14th with possible rates of 100 meteors per hour under ideal conditions. Its bright medium-slow meteors diverge from a radiant point close to Castor but appear in all parts of the sky. That radiant climbs from our NNE horizon at nightfall to cross the high meridian at 02:00. Last year’s show was swamped by moonlight, but the last quarter Moon is less obtrusive this year.
Jupiter, more than twice as bright as Sirius and improving further from mag –2.3 to –2.5, rises in the ENE some 40 minutes after our map times to dominate our sky from mid-evening onwards. Almost fixed in place to the right of the Sickle of Leo, and less than 8° NW of Regulus, it climbs high into the S by 05:00 on the 1st and 03:00 at year’s end, and is conspicuous in the SW before dawn.
Catch Jupiter near the Moon on the 11/12th when it lies 717 million km from us and appears 41 arcsec in diameter through a telescope.
Mars lingers as an evening object low in the SSW to SW, its altitude as seen from Britain one hour after sunset increasing from 12° to 17° as it tracks ENE through Capricornus and dims slightly from mag 1.0 to 1.1. Setting by about 19:30 throughout the period, it stands to the left of the young earthlit Moon on Christmas Eve.
Venus, brilliant at mag –3.9, is emerging from the Sun’s far side to hover low in the SW as the night begins. Its altitude at sunset improves from only 4° on the 15th to 7° as the year ends.
Saturn, mag 0.6 and slipping from Libra into Scorpius, rises in the ESE some 70 minutes before sunrise on the 1st and more than 3 hours before the Sun on the 31st.
December diary
6th 05h Moon 1.5° N of Aldebaran; 12h Full moon
8th 10h Mercury in superior conjunction
9th 07h Jupiter stationary
12th 04h Moon 5° S of Jupiter
12th 18h Moon 4° S of Regulus
14th 07h Peak of Geminids meteor shower; 13h Last quarter
17th 01h Moon 2.8° N of Spica
19th 21h Moon 1.5° N of Saturn
21st 23:03 Winter solstice
22nd 02h New moon
25th 08h Moon 6° N of Mars
28th 19h First quarter
