Interiors of Terrestrial Planets. Mercury MEAN RADIUS: 2439.7 km MASS: 0.055 (Earth=1) DENSITY: 5.43...
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Transcript of Interiors of Terrestrial Planets. Mercury MEAN RADIUS: 2439.7 km MASS: 0.055 (Earth=1) DENSITY: 5.43...
Mercury
•MEAN RADIUS: 2439.7 km •MASS: 0.055 (Earth=1) •DENSITY: 5.43 (g/cm^3) •GRAVITY: 0.376 (Earth=1) •ORBIT PERIOD: 87.97 (Earth days) •ROTATION PERIOD: 58.65 (Earth days) •SEMIMAJOR AXIS OF ORBIT: 0.387 au •ECCENTRICITY OF ORBIT: 0.206
The Resonant Rotation of Mercury
Mercury’s large core may indicate a “mantle-stripping” impact with a similar body.
1 solar day =176 Earth days
1 sidereal day=59 Earth days
Venus•MEAN RADIUS: 6051.9 km •MASS: 0.814 (Earth=1) •DENSITY: 5.24 (g/cm^3) •GRAVITY: 0.903 (Earth=1) •ORBIT PERIOD: 224.7 (Earth days) •ROTATION PERIOD: 243.0 R (Earth days) •SEMIMAJOR AXIS OF ORBIT: 0.723 au •ECCENTRICITY OF ORBIT: 0.007
The External Appearance of Venus
Venus in visible light – cloud shrouded
Venus in the ultraviolet – cloud patterns rotate every 4 days.
Radar Maps of Venus
The Magellan probe provided a high resolution elevation map of Venus, with information on reflectivities that indicate textures.
The Real Surface of VenusActual pictures from the ground -- the Soviet Venera seriesTemperature: 800 degrees, Pressure: 100 atmospheres
Mars•MEAN RADIUS: 3388.0 km •MASS: 0.108 (Earth=1) •DENSITY: 3.94 (g/cm^3) •GRAVITY: 0.380 (Earth=1) •ORBIT PERIOD: 686.98 (Earth days) •ROTATION PERIOD: 1.026 (Earth days) •SEMIMAJOR AXIS OF ORBIT: 1.524 au •ECCENTRICITY OF ORBIT: 0.093
Clouds, Polar Caps, and Odd MarkingsMars presents many different aspects to us. Its weather and terrain are varied and changeable.
Evidence of Water FlowsWater cannot be a liquid on Mars’
surface now, but billions of years ago it flowed (there may even have been seas.
The Surface Desert of Mars
Mars looks like a desert with about the same land area as the Earth. Its pink skies, however, contain far too little pressure to allow outside living.
Martian Moons: Phobos and Deimos
Mars’ moons are very small; almost certainly captured asteroids. Phobos orbits in less than a day – retrograde.
The Greenhouse Effect
1) In equilibrium, a planet must re-radiate all the energy it absorbs.
2) Solar energy tends to be converted from visible to infrared radiation.
3) Some gases are transparent to visible radiation, but opaque to infrared radiation.
4) When radiation is blocked, you need a bigger temperature gradient to push the energy through.
Evolution of Terrestrial Atmospheres
All the terrestrial planets start off with a substantial atmosphere. Mars lost most of it because of low escape speed. Earth converted most of the carbon dioxide into rocks. Life produced free oxygen. Venus lost the water because it stayed vapor (and solar UV released hydrogen).