Hubble's best view of Mars

The Hubble Space Telescope (HST) has taken its best ever image of Mars.

The picture shows frosty, white, water-ice clouds and swirling orange dust storms above a vivid rusty landscape.

The image was taken on 26 June when Mars was approximately 68 million kilometres (43 million miles) from Earth - the closest the Red Planet has been to Earth since 1988.

Hubble can see details as small as 16 km (10 miles) across. Unlike the orbiting Mars Global Surveyor, which takes detailed images of small regions, Hubble can provide an instant global view of the planet.

Storm activity

Astronomers say the large amount of seasonal dust-storm activity is especially striking. One large storm system can be seen churning high above the northern polar cap, with a smaller dust-storm cloud nearby. Another large dust storm is spilling out of the giant Hellas impact basin in the southern hemisphere.

Although Hubble has observed Mars before, it has never seen such detail because the Red Planet has never been so close since the HST was launched in 1990.

The biennial close approaches of Mars and Earth are not all the same. Mars' orbit around the Sun is markedly elliptical; the close approaches to Earth can range from 56 million km (35 million miles) to 101 million km (63 million miles).

The Mars opposition of 2001 (this event sees the Earth lie directly between the Sun and the Red Planet) serves as a prelude for 2003 when Mars and Earth will come within 56 million km (35 million miles) of each other. That will be the closest they been since 1924 and will not be matched again until 2287.