AS101 Lecture Notes - Lecture 1: Spiral Galaxy, Supercluster, Observable Universe
Document Summary
68. 3% dark energy, 26. 8% dark matter, and 4. 9% atoms (dark means not visible) Everything we can see is a tiny fraction. Massive ball of glowing gas that generates energy through nuclear fusion. About 100 times as wide as the earth. Indirect source of almost all energy on earth (almost all energy comes from the sun) Two types of planets are rocky and gaseous, sun is mostly gaseous (vapour state) Planet classification: non luminous and spherical, in orbit around a star, cleared the neighbourhood ( no objects of similar regions or mass in area) of other objects. Over 1500 planets confirmed to be orbiting other stars. Thousands of candidate exoplanets, observed by the kepler space telescope (tries to find an earth-like planet with a habitable zone, finding life in the universe) some planets have satelites other objects in the solar system. Asteroid is a small, rocky object orbiting a star. The smaller the objects are, the more irregular they appear.
