Sussex twitterers could be among the forefront of a global “Twitter Meteorwatch” tonight.

An astronomical society is organising a “meteor star party” and is calling on guests from all over the world to live tweet images of the annual Perseid meteor shower.

And the National Trust has named Black Down, the highest point on the South Downs, as one of the top seven places in the UK to spot the shooting stars.

Newbury Astronomical Society is organising the star party, after a successful Twitter Moonwatch in May.

The society’s president Richard Fleet said: : "We realised early on that what people want are images of the night sky, so we used our array of telescopes and cameras to provide a constant stream of pictures which we uploaded straight to Twitter.

"We were amazed at how excited people were about our Twitter Moonwatch; we had thousands of people who had probably never looked through a telescope before asking us questions directly and viewing images."

The mass participation event is planned as part of the International Year of Astronomy.

The Perseid meteor shower occurs every summer as the Earth's orbit takes it through debris scattered by the tail of Comet Swift-Tuttle.

As many as 50 to 80 meteors could be seen streaking overhead every hour.

Shooting stars occur as small particles, often no bigger than a grain of sand, enter the Earth's atmosphere at high speed and burn up.

The best time to see the Perseids will be after 10.30pm tonight, in the early hours of tomorrow morning, and Wednesday night.

Robin Scagell, vice-president of the Society for Popular Astronomy, said: "You can look anywhere up in the sky at about a 50 degree angle, or comfortable eye height. South is as good a direction as any. Under good conditions you might see one meteor every few minutes, or one or two a minute if you're lucky."

A quarter moon will mean the sky is not as dark as it could ideally be, but the meteors should still put on an impressive display.

The National Trust has published online guides to seven top Perseid viewing sites, including coastal spots, nature reserves and national parks.

Jo Burgon, head of access and recreation at the Trust, said: "Light pollution from our towns and cities has increased so much in recent years, but head out to the countryside for the perfect place to explore the beauty of the night sky, away from the intrusive glow."

The seven top sites named by the National Trust are Black Down, Sussex, the highest point on the South Downs, Teign Valley in Devon, part of Dartmoor National Park, Penbryn Beach in Wales, Stonehenge Landscape, Wiltshire, the chalk downland of Salisbury Plain surrounding the national monument, Wicken Fen national nature reserve in Cambridgeshire, Mam Tor in Derbyshire, and Friar's Crag in the Lake District, Cumbria.