Africa, Australia await eclipse

Southern Africa will experience its second total eclipse of the Sun inside 18 months on Wednesday.

The 4 December event starts out in the Atlantic Ocean just after dawn.

The Moon's dark shadow, or umbra, will then race eastwards across the surface of the continent, traversing countries including Angola and Zimbabwe, before heading out over the Indian Ocean to just touch Australia.

The eclipse is not a long one. At its maximum, it lasts just two minutes - although you would need to be in a boat 2,000 kilometres southeast of Madagascar to witness it.

Astronomers and doctors stress that a partially eclipsed Sun should never be looked at with the naked eye - even at the moment of total eclipse, skywatchers would be well advised to use optical protection.

Mistakes could result in blindness.

Narrow band

The path of totality - the track over the Earth's surface taken by the Moon's full shadow - is much narrower than during the eclipse in June 2001.

Total Eclipse 2002
Starts at 0550 GMT in the Atlantic
Ends at 0912 GMT in Australia
Longest period of darkness is 2m4s
Much of the rest of Africa, Indonesia, Australia and eastern Antarctica will witness a partial eclipse

At its widest, it will stretch just 87 km, about half the size it was last time.

The event starts in the South Atlantic where the umbra swings through space to touch the Earth at 0550 GMT.

At this point, totality lasts only 55 seconds and is visible along a path just 31 km wide.

Seven minutes later, the shadow reaches the coast of Angola and moves across the African landmass, touching Zambia, Namibia, Botswana, Zimbabwe, South Africa and Mozambique.

Viewed from South Africa, the eclipse lasts 85 seconds. The Sun and Moon are about 42 degrees above the horizon.

Very fast

The lunar shadow leaves the continent at 0628 GMT, having spent 91 minutes crossing the region. It then begins a long trek across the Indian Ocean. For 90 minutes the shadow touches no land.

But it is out at sea that the greatest duration of totality occurs, lasting two minutes and four seconds.

Just before the eclipse ends at 0912 GMT, it reaches the shore of South Australia.

At this point, the Sun and Moon are just nine degrees above the horizon and totality lasts just 33 seconds.

The Moon's shadow enters the Australian outback only fleetingly before the umbra leaves the Earth's surface and swings out into space.

Over the course of three hours and 21 minutes, the Moon's dark shadow travels approximately 12,000 km. At times the front of the umbra will be moving in excess of 4,000 km per hour.

BBC News Online will be reporting in full on Wednesday's eclipse, and we will want to hear from you and see your pictures. Click back soon.