Antarctic Circle

positional astronomy

apparent solar day

precession

apparent solar time

precession of the equinoxes

Arctic Circle

projection

autumnal equinox

*right ascension

celestial equator

*sidereal clock

celestial sphere

*sidereal day

circumpolar

sidereal time

constellation

sidereal year

*declination

south celestial pole

diurnal motion

summer solstice

ecliptic

time zone

ecliptic plane

tropical year

epoch

Tropic of Cancer

equinox

Tropic of Capricorn

lower meridian

upper meridian

mean solar day

vernal equinox

mean sun

winter solstice

meridian

zenith

meridian transit

zodiac

north celestial pole