The orbit of Mars regularly undergoes changes that greatly affect how much sunlight reaches the planet’s surface, which in turn can strongly alter the Red Planet’s climate. Similar orbital variations called Milankovitch cycles are known to happen on Earth.
Previous Martian climate models suggested that such orbital changes could lead to ice ages on Mars, when ice would cover most of the planet. Now, researchers said they have found evidence of these ice ages on Mars.
Whereas ice ages on Earth involve polar ice caps growing in size, prior work suggested that Martian ice ages would involve shrinking polar ice caps. Meanwhile, on the Red Planet, glaciers at mid-latitudes away from the poles would grow; during the interglacial periods between ice ages, ice would rapidly accumulate at the poles, while mid-latitude glaciers eroded away.
This is because Mars can tilt more than Earth, causing the Red Planet’s poles to receive more direct sunlight than its mid-latitudes, making for longer summer days with higher temperatures, said study lead author Isaac Smith, a planetary scientist who did this work at the Southwest Research Institute in Boulder, Colorado, and who is now at the Planetary Science Institute in Tucson, Arizona.
Hunting an ice age on Mars
To look for evidence of the comings and goings of ice ages, scientists examined radar scans of Mars’ polar ice caps taken by the Mars…