The Moon Origins And Features Lunar Formation Models The moon is a sister world that formed in orbit around Earth as the Earth formed. The moon formed somewhere else in the solar system then was captured into orbit around Earth. Early Earth spun so fast that it spun off the moon. Impact by Mars-sized proto- planet 4.5 billion years ago Explains: Chemistry Orbit High angular momentum Current accepted theory of the Origins of The Moon About 1/6 the size Just over the density Just over 1/10 of the gravity Chemistry of the rocks matches rocks found in Earths crust and upper mantle Very little core No spinning core, no magnetic poles EarthMoon Mean diameter12,742 km3,476 km Volume x km x km 3 Mass x kg7.349 x kg Mean density Surface gravity9.78 m/s m/s 2 Escape velocity11.2 km/s2.38 km/s Visual albedo Visual magnitude Earth/Moon comparisons PerigeePerigee 363,300 km MeanMean 384,400 km ApogeeApogee 405,500 km If you could fly to the Moon at a constant speed of 1000 kilometers per hour, which is the speed of a fast passenger jet, it would take sixteen days to get there. Apollo astronauts reached the Moon in less than four days even though they coasted "uphill" almost the entire distance. They got a fast start. The Sun happens to be 400 times the Moon's diameter, and 400 times as far away. That coincidence means the Sun and Moon appear to be the same size when viewed from Earth. A total solar eclipse, in which the Moon is between the Earth and Sun, blocks the bright light from the Sun's photosphere, allowing us to see the faint glow from the corona, the Sun's outer atmosphere. When the Moon is at apogee, it is 11% farther from Earth than it is at perigee. This is far enough that it cannot entirely block the bright light, so eclipses which occur near apogee are not total. Moons Surface Features The Highlands Highlands light areas, rough terrain, small mountains Mostly anthracite (plagioclase feldspars - lots of calcium and aluminum) In place rocks are 4.5 to 4.3 billion years old. The oldest part of the Moons surface The Maria (Mare) Lowlands dark, smooth (16% of surface) Basalt fine grained dark igneous rock rich in iron and magnesium (stuff that sank in magma ocean) Few hundred meters thick Rocks are 4.3 to 3.1 billion years old volcanic flows as recently as 1 billion years ago Lava Tubes - Rilles Rilles lava tubes as seen from space Craters Tyco Crater Young 100 MYr 85 kilometers across Fresh (rays) = young Created by impact of meteors. Due to very little atmosphere they do not burn up and rain down on the surface frequently At impact debris is thrown upward forming a rim and extra material splashes Out in a circular pattern called rays. Rays bits is material thrown Outward in all directions Which craters are older? Which are younger? Lunar Soil - Regolith No organic matter How are they different in terms of geologic processes? And WHY? Active wind/water erosion Impacts Active volcanoes Earthquakes Active magnetic field Few craters Geologically Active! NO Active wind/water erosion Impacts NO active volcanoes Small moonquakes NO active magnetic field Buckets of craters Geologically Inactive