ASTR 103 Lecture Notes - Lecture 9: Aeroshell, Mariner 6 And 7, Atmospheric Tide
12 Oct 2017
School
Department
Course
Professor
Document Summary
Earth-based optical observations of mercury are difficult. At its greatest eastern and western elongation, mercury is never more than 28 degrees from the sun. It can be seen for only brief periods just after sunset or before sunrise. Solar transits occurs about twelve times a century when the sun, earth and mercury are aligned. Mercury rotates slowly and has an unusual spin-orbit coupling. Radio telescope observations from sites such as arecibo gave evidence of a non-synchronous orbit. Mercury spins 1 times on its axis for every complete orbit. Mercury spins 3 times during every 2 orbits. Strong tidal effects, mercury"s slightly elongated shape and its very eccentric orbit cause this strange 3-to-2 orbit. A day of solar light on mercury would be 88 earth days. Images from mariner 10 revealed mercury"s heavily cratered surface. Most of our detailed information about mercury"s surface is from the mariner 10 flyby. Mariner only saw one side of the planet mission in 1974/75.
