Cold planet: The many ice ages of Mars

0 Comments | AFP, September, 2007

PARIS (AFP) — Mars has experienced 40 major ice ages over the past five million years, when vast areas of its porous soil froze and thawed again, according to computer simulations released on Wednesday.

The changes mainly result from Mars' angle of rotation, which is so extreme that the Red Planet experiences seasons. These seasons last far longer than Earth's because of the greater distance from the Sun.

Sub-surface ice exists in stable form today in both northern and southern hemispheres of Mars poleward of around 60 degrees latitude.

Historically, though, the extent of the ice has shifted again and again, eastwards and westwards and northwards and southwards, thanks to shifts in exposure to sunlight caused by Mars' rotational tilt, says University of...