Earth Sciences 1086F/G Lecture Notes - Lecture 6: Terrestrial Planet, George Darwin, Igneous Rock
4 Apr 2016
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The terrestrial planets: an introduction: mercury, venus, earth, mars! All have rocky bodies of similar composition:: silicon (si), oxygen (o), aluminium (al), magnesium (mg), sulfur (s), iron (fe), an igneous rock, primary product of volcanic lava, ne grained, dark grey to black! Basalt is the most abundant rock type among them! The closer a planet to the sun (larger gravitational effect) the more it gets bombarded by asteroids, leaving the surface extremely cratered (mercury)! Earth has a natural satellite (moon) whereas mars has 2 small misshapen ones, and venus. Moon is unusual:! and mercury have none: relatively large to earth, very low density being associated with a terrestrial planet, core accounts for 2-4% of mass (earth"s is 30%), abnormally high angular momentum! Explaining the origin of the moon is a very active research topic today, 3 hypotheses were suggested earlier:: fission hypothesis - where the moon broke off from a rapidly spinning earth!
