AST101H1 Final: Final Exam Study Notes

• School: UTSG
• Department: Astronomy & Astrophysics
• Course: AST101H1
• Professor: Michael Reid

Document Summary

Light year is distance light travels in one year. 1 au ~ 8 light minutes, black hole ~ 26,000 light years: andromeda galaxy is 2. 5 million light years away (the closest galaxy to earth) Light travels at finite speed and therefore we can"t see everything in the universe as it is now. Thus, no matter where we look, we are looking back in time: stars are huge spheres of super-hot gas (plasma) that produces energy by nuclear fusion (smashing atoms together). The sun is a fairly typical star: planets are large bodies which orbits stars. Planets may be various mixtures of rock, ice or gas. Planets orbit stars directly (not other planets) Planets must be massive enough for their own gravity to compress them into spherical shapes. That is, there can"t be a lot of other stuff orbiting the parent star in orbits very similar to the planet: pluto is now called a dwarf planet.