AST101H1 Study Guide - Midterm Guide: Oort Cloud, Liquid Hydrogen, Mariner 10

• School: UTSG
• Department: Astronomy & Astrophysics
• Course: AST101H1
• Professor: Bryan Gaensler

Document Summary

Solar system: the sun, the planets and all of their moons. The universe: the totality of all space, time, energy and matter. = average distant between earth and the sun. Distance between the sun and the nearest star: 41,746,980,000,000,000m. Stars are balls of plasma which produce energy by nuclear fusion. Planets are rocky, icy or gassy, they don"t produce much energy. Why is pluto no longer considered a planet: because it"s orbit is full of other stuff. (mainly comets) Definition for planets: planets orbit stars directly (not other planets, planets must be massive enough for their own gravity to compress them into spherical shapes, planets must have cleared their orbits. That is, there can"t be a lot of other stuff orbiting the parent star in orbits very similar to the planet. (failing this will be called dwarf planets) A moon is any large body that orbits a planet: titan is not a planet only because it orbits saturn.