ASTR 5 Lecture Notes - Lecture 2: Atomic Mass, Atomic Number, Ballpoint Pen
Document Summary
Bringing context to our search: universe is vast and old. Lightyear (ly) : unit of distance, (speed of light)*(seconds in 1 year) ~ 10 trillion km / 6 trillion mi. When we look at something a billion lightyears away, we look at an image of what it looked like a billion years ago. Speed of light = 300k km/s / 670m mph. Same physical laws operating on earth operate throughout the universe. Rocky planet that takes about 50 hours to circle at the equator. Spins on axis once per day while moving in a huge orbit around the sun per year (the two are not related) Time for light to travel from sun to earth is ~8 min 20 s. Everything in the solar system excluding the sun added up ~ mass of 2. 5. Sun is ~ 10 jupiters in diameter, ~ mass of 1k jupiters. Neptune = 30*earth"s distance from the sun, or 30 au.
