Celestial Sphere: an imaginary sphere on which all the celestial objects would appear
Celestial object: any object in the sky that genuinely appears to rise in the east and set in the west
Includes the moon, sun, stars, planets, and anything else in the
nighttime or daytime sky
Stars that are overhead follow same path as the sun (rise in the east and set in the west)
Stars that are close to Polaris (the Celestial North Pole) appear to move in circles around Polaris (circumpolar stars). These stars are in the Northern Sky
Stars in the Southern Sky rise and set near the horizon because they are mainly visible in the southern hemisphere
Apparent pattern that people use to mark the position of the stars
88 constellations The sky is divided into these 88 regions
each associated with a constellation Constellations change with the season