ASTR 100 Lecture Notes - Lecture 1: Astronomical Object
Document Summary
Astronomy: is the study of the universe; which is everything that exist. Our universe: 13. 7 yrs old, it has been expanding and cooling since the big bang. A colossal explosion involving everything in the universe. Marked the beginning of time: only able to see 4% of our universe. Why study the universe: except for hydrogen in the water all the atoms in our body were made from the stars, stars generate energy by making heavier element out of light ones. We are stardust: dying star eject those elements into space in a massive explosion, new stars, planets and even humans form. Scales of size and time: astronomy deals with object on a vast range of size and time scales, earth to the moon = 3. 8x105. The moon is only the diameter of earth: 1 astronomical unit (au) = avg. distance from earth to sun. Our sun: self-luminous celestial object it has internal source of energy for its light.