AST101H1 Chapter Notes - Chapter 2: International Astronomical Union, Celestial Equator, March Equinox

• School: UTSG
• Department: Astronomy & Astrophysics
• Course: AST101H1
• Professor: Bryan Gaensler

Document Summary

On clear, moonless nights far from city lights, more than 2000 stars may be visible to your naked eye, along the whitish band of light that we call the milky way. Constellation: a region of the sky with well-defined borders; the familiar patterns of stars merely help us locate the constellations there are 88 official constellations; chosen by the international astronomical union (iau) Celestial sphere: the imaginary sphere on which objects in the sky appear to reside when observed from earth. North celestial pole is the point directly over earth"s north pole. South celestial pole is the point directly over earth"s south pole. Celestial equator is a projection of earth"s equator into space, makes a complete circle around the celestial sphere. The ecliptic is the path the sun follows as it appears to circle around the celestial sphere once each year: it crosses the celestial equator at a 23. 5 angle, because that is the tilt of earth"s axis.