Tuesday, June 16, 1998 Published at 11:36 GMT 12:36 UK
Winter on Mars is much like the Earth.
Olympus Mons in morning light
The Mars Global Surveyor spacecraft has taking some remarkable images of the onset of winter in the northern hemisphere of Mars. Our science correspondent David Whitehouse reports:
From Martian orbit, the Mars Global Surveyor (MGS) has been paying particular attention to winter weather patterns, cloud formations and extinct Martian volcanoes.
It has taken a remarkable image of the largest extinct volcano on Mars, Olympus Mons. It is 550km (340 miles) wide and is frequently covered by clouds.
The new image shows it during Martian mid-morning (the Mars day is only about 30 minutes longer than ours.)
Several different types of cloud features can be seen. So-called 'gravity wave clouds' are visible. These form downwind of mountains and crater rims under specific atmospheric conditions.
The clouds are probably made of ice crystals but high altitude and latitude clouds can be made of crystals of carbon dioxide or 'dry ice'.
During the winter, the weather on Mars is rather Earth-like, with cold, cloudy mornings and cool, hazy afternoons.
Unfortunately it is very cold and the atmosphere is not breathable.