Astrophysics (Index)About

solar day

(synodic day, synodic rotation period)
(length of a solar system planet or Moon's day)

The solar day is the length of time for a position on a rotating body to face the Sun again, on Earth, noon to noon at some given location, i.e., what we normally call a day. The term is used for other bodies such as solar system planets and moons. Examples:

Bodyapprox. solar day
Mercury176 Earth days
Venus117 Earth days
Earth24 hours
Mars24 hours 40 minutes
Jupiter10 hours
Saturn10.5 hours
Uranus17 hours
Neptune16 hours
Pluto6.4 Earth days
Ceres9 hours
Moon29.5 Earth days
Titan16 Earth days

Mars researchers often use the term Sol for the solar day of Mars.

In contrast, a body's sidereal day is the length of time it takes some given location on the body to face the same point within the celestial sphere, basically when it faces the same stars again. Given that a the direction that faces the Sun from a solar system body constantly changes as the body orbits, its solar day generally differs from its sidereal day. The percentage difference is small if the body has numerous solar days in its year: the difference for Earth is about 4 minutes. The two solar system planets with significantly differing solar and sidereal days are Mercury (176 versus 59 Earth days) and Venus (117 versus 243 Earth days).


(measure,time,Sun,solar system)
Further reading:
https://en.wikipedia.org/wiki/Synodic_day
https://astronomy.swin.edu.au/cosmos/S/Solar+Day
http://cseligman.com/text/sky/rotationvsday.htm
https://scienceworld.wolfram.com/astronomy/SolarDay.html
https://www.oxfordreference.com/display/10.1093/oi/authority.20110803100516788
https://dictionary.obspm.fr/?showAll=1&formSearchTextfield=solar+day
https://www.theplanetstoday.com/which_planet_has_the_longest_day.html

Referenced by pages:
Ceres
Jupiter
Mars
Mercury
moon
Neptune
Pluto
Psyche
rotation period
Saturn
solar time
synodic period
Terrestrial Time (TT)
tidal locking
Titan
Uranus
Venus

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