AS101 Study Guide - Midterm Guide: Solar System, Great Circle, Right Ascension
Document Summary
Astronomical unit (au): the average distance from the earth to the sun. Solar system: the sun and its asteroids, planets, comets and so on. Planet: a non luminous body in orbit around a star; large enough to be spherical and to have cleared its orbital zone of other objects. Star: a globe of gas held together by its own gravity and supported by the internal pressure of its hot gases, which generate energy by nuclear fusion. Light year (ly) unit of distance equal to the distance light travels in one year. The nearest star system is alpha centauri 44 trillion km. From largest to smallest: universe, walls, voids, filaments, superclusters, clusters, galaxy, solar system, star, planet. The local group: a group of 40 galaxies. Belongs to the local supercluster (aka virgo supercluster) Jupiter is 10 times bigger in diameter than the earth. Size of the milky way: about 80 000 ly. Distance to a nearby galaxy: 2 600 000 ly.
