AST101H5 Chapter Notes - Chapter 1: Lunar Eclipse, Lunar Phase, Red Color
Document Summary
Stars are at such huge distances that we cannot get any sense of their true three- dimensional arrangement in space where we can view them. For the purpose of naked eye observations, we can therefore treat all stars as if they are the same distance from earth, and imagine that they lie on the inside of a gigantic dome that stretches overhead. This dome seems to stretch to where the sky meets the ground along a horizontal circle that we call the horizon. Astronomers picture the dome of the night sky as half of the celestial sphere, which surrounds the earth. When we stand on earth, the ground blocks our view of about about half the celestial sphere. A way of simplifying the arrangement and motions of celestial bodies so they are easier to visualize. When ancient people looked at the night sky, they noticed stars formed fixed patterns on the celestial sphere, what we today call constellations.
