Downton Sky At Night

Downton Sky at Night - December

by Michael F. Barratt FRAS

Prominent winter constellations are now visible.  The Pleiades open star cluster is now very prominent in the night sky in the east, together with its sister open cluster, the Hyades, both in the constellation of Taurus the Bull.

Mercury is at its morning brightest  during the first half December, rising in the east at around 6 am. On the morning of 17 December, it will appear just to the left of the waning crescent Moon.  Venus and Mars are both lost to the sun’s glare this month.  Jupiter is the brightest planet visible in the sky. It rises at around 6pm. and shines brilliantly all night. It will be found in the constellation of Gemini (the Twins) close to its two brightest stars, Castor and Pollux. Saturn, the other gas giant, can be seen after dark just under the Great Square of Pegasus, setting around midnight.

Three Comets have been visible in the night sky recently. Comets SWAN and Lemmon are periodic comets which come from the Oort Cloud (a band of cosmic rocks and debris and dust which surrounds our own Solar System) and which orbit the Sun, whilst ATLAS is an interstellar object which has come from another star system and is merely passing through our own solar system. More information from the Society for Popular Astronomy (popastro.com).

The full moon on 4 December is known as a “Cold Moon”. It will be a “Supermoon” (when it is also at its closest point to Earth in its orbit) as well as occulting (covering up) the Pleiades star cluster.

The Geminid meteor shower is best observed on the night of 13/ 14 December but will be visible for a few days either side  - you can expect to see the remnants of Phaethon (an asteroid) streaking northwards across the sky. The Ursids occur  every year on the night of 24/25 December.  This year, the moon sets early, so the shower should be clearly visible.