Chris Lintott

A lunar eclipse in Germany in July. The colour of the moon can range from orange to barely visibleAP

The highlight of January’s sky is a total lunar eclipse, perfectly timed for observers in the British Isles on the morning of January 21. Events such as this occur when the Moon passes through the Earth’s shadow; the vagaries of orbital mechanics mean that this happens only occasionally.

A lunar eclipse, especially when the Moon is close to the horizon, can be spectacular, but January’s show will start quietly. The Moon will slip into the penumbral shadow at 2.37am, as the Earth begins to block the Sun as seen from the lunar surface, but little will be visible. Over the course of the next hour or so the Moon will appear to dim slightly before entering the umbra, where lunar observers would see the whole…