The Night Sky in December
The Geminid meteor shower, arguably the best of the annual showers, reaches peak activity on the night of December 13. A bright waxing gibbous Moon interferes for much of the night but there is a window of opportunity after moonset, which occurs around 3am on December 14 This leaves approximately 3 hours of true darkness for a Geminid watch.
Comet C/2021 A1 Leonard is predicted to appear at least binocular bright during December. There’s uncertainty as to how bright it will actually get, with an outside chance of it reaching naked-eye brightness around December 10-16. It’s poorly located from the UK, your best chance of spotting it probably December 1-13 in the morning sky, when it appears approximately 30 degrees up, in an east-south-east direction before the onset of dawn. From December 16 on, the comet is below Venus in the evening sky and unlikely to be seen unless it brightens unexpectedly. Comets can be unpredictable!
At 15:59 GMT on December 21, the centre of the Sun’s disc reaches its most southerly position against the background stars; the December solstice. The Sun’s apparent movement resumes in a northerly direction after the solstice.
Venus is currently hanging above the southwest horizon. Despite being the brightest planet, it’s not easy to spot as its post sunset altitude is low. On December 28, it is joined by dimmer, but still relatively bright, Mercury. Both planets will be visible low above the south-west horizon from 40 minutes after sunset. If you spot Mercury and Venus, don’t stop there. In order from the setting Sun, it’s currently possible to spot Mercury, Venus, Saturn, Jupiter, Neptune and Uranus. The latter two require at least binoculars to see.
Meteors once again steal the show at the start of 2022, with the peak of the annual Quadrantid shower occurring on the night of January 3-4. This is an active shower, highest rates typically experienced over just a few hours. The actual peak occurs early evening on January 3 when the shower radiant – where the Quadrantid’s appear to emanate from – is at its lowest altitude, due north. This isn’t ideal, rates improving with radiant altitude. However, the Moon is absent and if the weather stays clear, a number of Quadrantids should be seen.
On the evening of January 4, Mercury, Saturn and a slender waxing crescent Moon present an attractive early evening arrangement. Mercury appears at maximum apparent separation from the Sun in the evening sky, on January 7, the planet setting 100 minutes after the Sun on this date.
Orion is prominent in the January evening sky, the hunter easily identified thanks to the three middle-brightness stars forming a distinctive line at the centre of the constellation. Known as Orion’s belt, these stars are part of an open cluster known as Collinder 70. With several members visible to the naked eye, and many more picked out using binoculars, this is probably an open cluster you’ve looked at many times without realising what it is.
Hanging south of Orion’s belt is his sword, marked by a line of faint stars. Look at it using binoculars and you will see numerous stars with a misty patch in the centre. The mistiness is an emission nebula known as Messier 42, the Orion Nebula. The nebula glows because its gas is excited by hot ionising radiation from a small group of stars known as the Trapezium cluster at the cloud’s centre, the cluster having formed out of the nebula material.