PHYS133 Chapter Notes - Chapter 2: Star, Celestial Equator, Nautical Mile
3 Mar 2016
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With the unaided eye, we can see more than 2000 stars as well as the milky way. Stars at different distances all appear to lie on the celestial sphere (how we see the sky?) The ecliptic is the sun"s apparent path through the celestial sphere. The 88 official constellations cover the celestial sphere. Stars all appear to lie on the celestial sphere, but rally lie at different distances. A band of light that makes a circle around the celestial sphere. What is it: our view into the plane of our galaxy. We measure the sky using angles: fist 10 degrees, thumb to pinky 20 degrees, tip of finger 1 degree. Angular size = physical size x 360degrees/2(pi)(distance) An object"s angular size appears smaller if it is farther away. First, a ratio of two lengths: 1) physical size of object l, 2) 2(pi) x distance = 2(pi)d.
