Mars at its nearest

At 10:51 this morning, Mars and earth were a mere 35million miles apart, the closest they have been in 60,000 years. Scientists say the distance, tiny in astronomical terms, is about the closest the two planets can get.

Mars has been visible as a bright orange object in the night sky for many weeks. Sir Patrick Moore, presenter of the BBC's Sky At Night, said: "You can find it easily, it is so bright, in the south at midnight. You can't mistake it, bright and red." Mars is outshining everything else in the sky apart from the moon and Venus.

However, Londoners trying to spot it faced one major obstacle - cloud. Charlie France, at the Met Office, said the whole of Britain was likely to remain covered in cloud today, although it will clear later in the week to give a clear view of the planet.

In the capital, cloud permitting, Mars will be visible from 8:35 tonight in the south-eastern sky. However, those desperate to observe it should head to Tahiti, which astronomers believe will be the closest point on earth and offer the best views. With a small telescope, Mars watchers will be able to pick out surface details such as its southern ice cap.

They may also be able to spot Olympus Mons, at a height of 16 miles the biggest volcano in the solar system, which astronomers believe is now inactive.

The red planet, after reaching its closest point of 34,646,418 miles from earth, will slip away at an average of six miles a minute, or about 9,000 miles in the first day.

The close encounter is a consequence of the orbits the earth and Mars both take around the sun. Earth has a more-or-less circular orbit while Mars follows a more elliptical path.

This means that, at various times, Mars passes closer to earth than usual. Calculations suggest the last time they were this close was when Neanderthals roamed the planet, on 12 September, 57,617 BC.

Space agencies have taken advantage of the event to shoot four probes at Mars, and two Nasa missions, Europe's Mars Express and a Japanese orbiter, are on their way.

Mars Express, which was launched in June, has almost reached its halfway point with some 20 million miles left to travel.