PHYS139 Lecture Notes - Lecture 1: Blue Supergiant Star, Red Supergiant Star, Right Ascension

• School: University of Delaware
• Department: Physics and Astronomy
• Course: PHYS139
• Professor: Bouchelle Hank

Document Summary

Revolutions of planets: mercury- 88 days, venus- 225 days, mars- 2 yrs, jupiter- 12 yrs, saturn- 30 yrs, uranus- 84 yrs, neptune- 165 yrs, pluto- 248 yrs. Why do stars twinkle: light is distorted upon entering earth"s atmosphere. Sun"s gravity incredibly strong, like all stars- affects pluto, 4 billion miles away. Distances: earth"s diameter- 8,000 miles; moon= 2,000, distance to moon- 230,000 miles, distance to sun- 93 million miles. North pole: polaris never moves, big dipper circles north pole, always in sky, polar constellations draco, cassiopiea, cepheus. Sky changes 1 degree every day, 15 degrees every hour. Altitude/alzimuth test: compass , start north= 0 degrees, right ascension declination. Declination= latitude= degrees between equator and n. pole. North pole= 90 degrees: celestial equator-runs parallel to earth"s equator; north and south hemispheres of sky. Blue- hottest, burn out faster (millions of years), become red stars. Red- coolest, last longest (billions of years) White dwarves very hot but dim bc of size.