Chapter 7 Book Notes

Chapter 7 Book Notes - Astronomy 180 Chapter 7: The Other...

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Astronomy 180 Chapter 7: The Other Terrestrial Planets and Their Comparison to Earth (Pages 166-199) 4 basic groups of planets: similar in chemistry to the Earth (Mercury, Venus, Mars); especially rich in H and He (Jupiter, Saturn); containing vast quantities of H 2 O as well as H and He (Uranus, Neptune); rich in rock and ice (Pluto) I. Mercury Temperature extremes, thin atmosphere, deadly solar raidation II. Mercury: Photographs from Mariner 10 reveal Mercury’s lunarlike surface Inhospitable with crater-strewn surface (similar to our Moon) Exceptionally low albedo of 0.12; only bright to the eye because the sunlight scattering is intense Caloris Basin: most impressive feature; measures 1300km in diameter and lies along the terminator (border between day and night); surrounded by mountains, but beyond them are smooth plains Impact that created the basin pushed up jumbled hills on the opposite side of the planet Unlike the Moon, Mercury lacks extensive craterless regions Scarp – a cliff on Mercury believed to have formed when the planet cooled and shrank Planet’s interior is solid to a significant depth III. Mercury: More of Mercury’s interior is iron than the interior of the Earth Mercury is the most iron-rich planet in our solar system Theories about Mercury’s high iron content: only iron0rich minerals were able to withstand the solar heat so close to the sun; an especially intense outflow of particles from the young Sun stripped Mercury of its low-density mantle shortly after the Sun formed; during the final stages of formation, Mercury was struck by a large planetesimal, ejecting much of the lighter mantle IV. Mercury: Mercury’s rotation and revolution are coupled One of the most unique orbits in our solar system: with the sun, similar to the Earth & Moon; involves tidal bulges 3-to-2 spin-orbit coupling – The rotation of Mercury, which makes 3 complete rotations on its axis for every two complete orbits around the Sun A solar day on Mercury is 176 Earth days long, twice the length of its year Mercury has a weak magnetic field; rotates 59 times more slowly than Earth, hardly fast enough to generate one V. Mercury: Mercury’s atmosphere is the thinnest of all terrestrial planets Mercury’s mass is only 5.5% that of Earth; the force of gravity is too weak to hold a permanent atmosphere, but traces of 5 gasses have been detected around it; the atmosphere is at least 10 17 times less dense than our air Mercury’s temperature range is the most extreme in the solar system : this is due to its slow rotation & minimal atmosphere; at noon: 700K (800ºF); at the terminator: 425K (305ºF); at night 100K (-280ºF)
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Chapter 7 Book Notes - Astronomy 180 Chapter 7: The Other...

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