Explorations of the Universe
Mars
Mars
• About half the size of Earth
• Rotates in 24.5 hours
• Ranges from 207 to 249 million km (129 to
155 million miles) from Sun
• Period: 687 days
• Two tiny satellites
The Surface of Mars
• Thin carbon dioxide atmosphere about 1/150
as dense as Earth’s
• Surface temperatures -20 to -200 C
• Polar caps of ice and frozen carbon dioxide
• Large rift valley (Vallis Marineris)
• Huge Shield Volcanoes (Olympus Mons)
• Evidence for former liquid water
Mars as Lowell Knew It
Modern
Imaging
Technology
Improves
Earth-Based
Views of Mars
Greatly
Mars from Mariner 9
Mars Viking Mosaic
Vallis Marineris
Huge
Landslide in
Vallis
Marineris
Layered Deposits in Vallis Marineris
Olympus Mons
Summit of Olympus Mons
Phobos over Olympus Mons
The Polar Caps
Water on Mars
Channels on
Mars
Floods on
Mars
Where’s the Water Now?
How to Lose an Ocean
• If water is exposed to solar UV and
particles, it breaks down to H + O (photodissociation)
• Happens if water gets into upper
atmosphere
– Planet gets hot (Venus)
– Planet loses atmosphere (Mars)
• Oxygen combines with iron and other
elements, on Mars may also have escaped
Mars as Seen by Viking
Mars from Pathfinder
Martian Winter
Phobos and Deimos
The Face
on Mars