ASTR 101 Lecture Notes - Lecture 5: Photon, Electromagnetic Spectrum
13 Dec 2016
School
Department
Course
Professor
Document Summary
Magnitude - a unit for how bright a star is. Apparent magnitude - how bright a star seems to you. On a scale like golf - the bigger the score, the dimmer the star is; the lower (negatives,) the brighter it is. Magnitude +0 is 100 times brighter than magnitude +5. Orbits due to gravity can be circles or ellipses. Kepler"s 3 laws naturally are derived from assuming that all planets orbit the sun. Jupiter"s moons orbit jupiter due to the gravity of jupiter. The sun does not steal moons because of the 1/distance-squared dependence of gravity. Inner planets orbit in shorter periods so naturally they get lapping of planets to create. All made sure science was based on observations and not abstract theory. Newton published his 3 laws and the law of gravity in 1687. With calculus and gravity you can calculate the motions of cosmic objects; gave a whole new approach on how to think about celestial objects.
