AST 104 Lecture Notes - Lecture 1: Spiral Galaxy, Scientific Notation, Astrophysics
Document Summary
Stars" spectra teach us about their composition, their size, and their temperature. The motion of stars in galaxies proved that the universe if filled with dark matter of an unknown character. The contents: stars, gas, and their organization. The driving force for organization and dynamics. Earth: 13,000 km or 1. 3 x 10 4 km. Radius of the moon"s orbit around the earth: 380,000 km or 3. 8 x 10 5 km. Solar system diameter: 10,000,000,000 km or 1 x 10 10 km. Nearest stars: 200,000,000,000,000 km or 2 x 10 14 km. Typical spiral galaxy diameter: 1 x 10 18 km. When multiplying two numbers written in scientific notation, simply add the exponents of the powers of 10. 1 10 4 2 10 5 = 1 2 10 (4+5) = 2 10 9. When dividing two numbers given in scientific notation, simply subtract the exponents.
