CROSS your fingers for a clear sky on Hallowe'en, writes STUART ATKINSON. If the clouds stay away there will be a lovely sight on view in the twilight just as the first costumed trick or treaters are beginning their rounds.

Look to the south west after sunset on Hallowe'en and you'll see a beautiful, slender crescent Moon shining to the upper left of a bright star. The 'star' will actually be a planet: Jupiter, the largest world in our solar system. Unlike our solid, rocky Earth, Jupiter is an enormous, bloated ball gases and liquids, and it is so huge it could hold a thousand Earths with room to spare.

At the moment Jupiter is clearly visible to the naked eye as a bright, blue-white star low in the western sky after dark, and on Hallowe'en it will be joined in the twilight by a sickle-thin crescent Moon. Through a pair of binoculars - and even with your naked eye if your sky is very clear and not ruined by light pollution - you'll be able to see the dark part of the Moon's disc glowing with a subtle, pinky-blue light. This is Earthshine, light reflecting off Earth and bathing the Moon's face.

If you look to the left of the Moon and Jupiter you'll see another planet there, a short distance away. This is Saturn, and on the evening after Hallowe'en the Moon will have moved on to lie between it and Jupiter.