IMPORTANT CELESTIAL PERIODS

Motion

Period

Comments

Sidereal Day

23 h 56 m 04 s

day according to the stars

Solar Day

>23 h 56 m 04 s

day according to the Sun

Mean Solar Day

24 h 00 m 00 s

average Solar day

Sidereal Month

27 d 07 h 43 m 11 s

Moon month with respect to the stars

Synodic Month

29 d 12 h 44 m 03 s

length of the lunar phase cycle

Sidereal Year

365 d 06 h 09 m 10 s

year with respect to the background stars

Tropical Year

365 d 05 h 48 m 46 s

year of the seasons

Precession

~25,800 y

slow rotation axis movement