ASTRO 101 Lecture Notes - Lecture 1: Milky Way, Observable Universe, Star Formation
Document Summary
Terms: solar system: consist of the sun (*star), planets and their moons (earth), rocky asteroids and icy comets. Star system: a star and planets and materials that orbits it. Milky way galaxy: a great island of stars in space. Local group: small groups of galaxies: galaxy clusters: groups of galaxies with many more large members. Universe: sum total of all matter and energy. Observable universe: portion of universe we can see (14 billion light-years) Universe > observable universe > superclusters > galaxy clusters > galaxy > solar system > star. Astronomical unit (au): earth"s average distance from the sun (150 million km) Light-year (ly): distance that light can travel in 1 year (10 trillion km: unit of distance - speed of light: 300,000 km/s, distance: n light-years = image: n years ago. Star: a large, glowing ball of gas, generates heat and light through nuclear fusion.
