Weather: Sky watch

This week offers an exciting sky-watching opportunity. At about 1.28am on Wednesday, observers in the UK can see Saturn disappear behind the dark, eastern edge of the gibbous Moon in the south-south-west sky. Jacqueline Mitton explains what to look for.

The tracks of the Sun, Moon and planets against the backdrop of stars are confined to a band around the sky broadly marked by the familiar zodiacal constellations. Every now and again, the Moon crosses directly between us and one of the planets, hiding it from view. This week, in the early hours of Wednesday morning (12 November), Saturn will dodge behind the gibbous Moon for just under an hour. The exact timing varies from place to place.

Viewed from London, the occultation lasts from 1.28am to 2.21am. Observers in Edinburgh will also see Saturn disappear at 1.28am, but will witness its re-emergence a few minutes earlier, at 2.10am. The Moon will be fairly low over the south-south-west horizon as Saturn glides behind its unilluminated eastern side.

The planet's reappearance from behind the Moon's brightly lit side will inevitably be less easy to detect with the naked eye. Lunar occultations of Saturn are quite rare. The next visible from the UK will occur in 2001.