Descriptive Astronomy 101
Fourth planet from the Sun
- 227.9 million km
Revolution = 687 days
Rotation = 24hr 37min.
Diameter = 6,794 km (4,194 mi.)
density = 3.9 g/cm3
Axial Tilt = 25°
Mass = 6.42 x 1023 kg
Escape velocity = 5000 m/sec
Average distance from Sun = 1.524 AU
Rotation period (length of day) = 1.026 days
Revolution period (length of year) = 686.98 days
Orbit inclination = 1.85°
Orbit eccentricity = 0.093
Maximum surface temperature = 240 K
Minimum surface temperature = 190 K
Visual geometric albedo = 0.15
Highest point on surface = Olympus Mons
- (about 24 km above surrounding lava plains)
Atmospheric components - 95% CO2, 3% N2, 1.6% Ar
Giovanni Schiaparelli, 1877 - "canali"
Percival Lowell, 1890
Differentiated core, mantle, crust
Core, 9-15% of planetary volume
Weak magnetic field suggesting solid core
Basaltic rock and altered materials
pyroxenite and diabase (ultramafic to mafic)
Samples have been found on Earth - SNC meteorites
Only 34 known samples from Mars
Dunite, pyroxenite, peridotite, diabase
Meteorite samples from Mars.
How is this possible?
How do we know that they are from Mars?
No Earth-like plate tectonics
Plate tectonics did not develop. Why?
Reason for large volcanoes is related to lack of plate tectonics on Mars.
Smaller diameter means more rapid planetary cooling.
- results in thick crust
- relatively immobile crust
Mantle plumes supply magma to single area over long periods of time.
Impact Craters are prevalent
Similar morphology to lunar craters
Ejecta material show a lobate form
Modified by erosion since formation
Stream channels and drainage patterns, and gullies.
The downhill movement of material under the influence of gravity
Slump - large blocks of material sliding or rotating downhill
Views from the surface
• Viking lander view of surface 1
• Viking lander view of surface 2
• Pathfinder lander view of the surface 1
• Pathfinder lander view of the surface 2
Mars Exploration Rover Mission - Spirit and Opportunity Rovers
Life on Mars?
Did life exist on Mars in the past?
Could life exist on Mars today?
Check the following site for more information and images on Mars
Mars Global Surveyor