Ch. 2 The Sky

3. is a unit of angular measurement equal to one-sixtieth of one degree
4. the line or circle that forms the apparent boundary between earth and sky
6. any of the various groups of stars to which definite names have been given
7. the point on the celestial sphere vertically below a given position or observer
10. the imaginary spherical shell formed by the sky, usually represented as an infinite sphere, the center of which is a given observer's position
12. the point on the celestial sphere that is due west of the observer, at this point the celestial equator crosses the horizon
13. the point on the celestial sphere vertically above a given position or observer
14. is a number that is a measure of a star's brightness as seen by an observer on Earth
15. is the point in the sky about which all the stars seen from the Southern Hemisphere rotate
16. can be material, visual, mathematical, or computational and are often used in the construction of scientific theories

1. a group of stars
2. a scale that measures how bright a star appears
5. of a point in an orbit past the point of periapsis measured in degrees
7. is a point in the sky about which all the stars seen from the Northern Hemisphere rotate
8. the point on the celestial sphere, due north of the observer, at which the celestial meridian intersects the celestial meridian intersects the celestial horizon
9. alternate expression to refer to the ascendant, the point where the eastern horizon intersects the ecliptic
11. the imaginary point on the celestial sphere at which the meridian intersects the horizon; it is due south of the observer
16. is one-sixtieth of an arcminute