AST101H1 Chapter Notes - Chapter 2: Apparent Retrograde Motion, Umbral Calculus, Orbital Period

• School: UTSG
• Department: Astronomy & Astrophysics
• Course: AST101H1
• Professor: Michael Reid

Document Summary

A constellation is a region of the sky with well-defined borders; the familiar patterns of stars merely help us locate the constellations. The names and borders of the 88 official constellations were chosen in 1928 by members of the international astronomical union (iau) The stars in a particular constellation appear to lie close to one another but may be quite far apart in reality, because they may lie at very different distances from. Ancient greeks imagined the stars and constellations to lie on a great celestial sphere that surrounds earth. Earth seems to be in the centre of the celestial sphere only because it is where we are located as we look into space. It crosses the celestial equator at a 23 angle, because that is the tilt of earth s axis. The band of light that we call the milky way circles all the way around the celestial sphere, passing through more than a dozen constellations.