AST 4.4 PPT

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4.4 TERRESTRIAL PLANETS

Transcript of AST 4.4 PPT

  • 1. 4.4TERRESTRIAL PLANETS

2. Mercury Overview
Innermost planet of the solar system; very similar to Earths moon.
Just over 1/3 of Earths diameter (moon ~ 1/4)
Lacks atmosphere
Heavily cratered surface
Lowlands flooded by ancient lava flows
3. Mercury Data
Until recently, most of our knowledge of Mercury was based on photos and measurements by the Mariner 10 spacecraft (1974-1975).
New spacecraft, Messenger (MEcurySurface, Space, ENvirnoment, GEochemistry, and Ranging mission) has conductedtwo flybys of Mercury and will make one more before it goes into orbit around the planet in March of 2011.
Conduct close up observations.
4. 5. 6. 7. Motions of Mercury
Like Earths moon (tidally locked to revolution around Earth), Mercurys rotation has been altered by the Suns tidal forces, but not completely tidally locked.
This gravitational influence is known as resonance.
Rotates not once per orbit, but 1.5 times per orbit.
Therefore, its rotational period is 2/3 its orbital period.
8. Mercurys Motion
Revolution ~ 88 days
Rotation ~ 59 days
Extreme day/night temperature contrasts exist on the planet:
(-170C) (430C)
Compared toEarths moon:
(-170C) (130C)
9. Craters
Heavily battered with craters of all sizes, including some very large basins.

  • Most are believed to have formed shortly after the heavy bombardment period.