Terrestrial Planets- Mercury & Venus THE SOLAR SYSTEM
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PLANETS All planets travel around the sun Some move faster than
others Revolution-the time it takes for a planet to complete one
orbit around the sun
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PLANETS Planets also spin around an imaginary center line
called the axis Rotation-the time takes for a planet to complete
one spin on its axis Some planets are tilted on their axis
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MERCURY Stats: 0.39 AU from the sun Rotation period: 1,407
hours (58 days) Revolution period: 88 days Axis tilt 0 Highest
surface temperature: 427C Lowest surface temperature: -184C
Gravity: 38% of Earths Diameter: 4,879 km
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MERCURY Has the shortest orbit time of any planet Has the most
elliptical orbit of any planet Planet is made of about 70% metallic
and 30% silicate minerals
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MERCURY Least understood of all the planets Only 2 missions
have gone to Mercury Mariner 10 (1973) MESSENGER (2004)
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MERCURY Mariner Program Designed to gather data about the inner
planets-Mercury, Venus and Mars Only the Mariner 10 probe went to
Mercury Launched in November, 1973 Flew past Mercury 3 times
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MERCURY Mariner Program Mapped about 45% of Mercurys surface
First close pictures of surface Also studied the magnetic field
around Mercury
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MERCURY MESSENGER Program Launched in August, 2004 Entered
Mercurys orbit in March, 2011 Data is still being collected and
analyzed
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VENUS Stats: 0.72 AU from the sun Rotation period: 5,832 hours
(243 days) Revolution period: 225 days Axis tilt 177 Average
surface temperature: 465C Gravity: 89% of Earths Diameter: 12,104
km
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VENUS Similar size and mass of Earth Has a Retrograde rotation
Clockwise spin of a planet from the north pole Also has the slowest
rotation of all planets
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VENUS Venus is surrounded by thick clouds Only 10% of sunlight
reaches the surface Cannot see the surface through the clouds
Atmosphere is extremely dense Made of 96.5% CO 2 and 3.5% N 2
Pressure is 93 times that of Earth Rains sulfuric acid
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VENUS Surface was mapped by the Magellan probe 80% of the
surface is smooth, flat plains 20% of surface form two, raised
continents 167 large volcanoes on the surface Features are very
well preserved No tectonic plates Entire surface is recycled every
300-600 million years
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VENUS Thousands of impact craters Between 3 and 280km in
diameter Objects causing craters less than 3km burn up in
atmosphere before impact
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VENUS Many different missions from the USA and Russia went to
explore Venus RussianAmericanOther Venera (1961-1984)Mariner 1-10
(1962-1973)Venus Express-ESA Vega (1986)Pioneer (1960,
1978)Akatsuki-JAXA Magellan (1989-1991) MESSENGER (2004-
present)
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VENUS Venera Project-16 missions, 10 successful landings First
probes to safely land on another planet First to return images of
another planets surface First to map the surface of Venus Probes
lasted between 23 min and 2 hours on surface
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VENUS Mariner Project-10 missions, 7 successful First planetary
flyby First planetary orbiter First use of gravity assist maneuver
Using gravity of a planet to accelerate a spacecraft
