THE DIFFERENCE BETWEEN THE EARTH (SOLAR) DAY AND THE EARTH SIDEREAL DAY.
Tables of Solar System time periods (ie:- orbital and rotation periods of planets and satellites) usually express these periods in Earth days, ie:- Earth SOLAR days, when an Earth SOLAR day = 24 hours. An Earth SOLAR day is the time period between successive risings of The Sun on a fixed horizon on Earth.
The Earth SIDEREAL day = 0.9972697 Earth SOLAR days.
The Earth SIDEREAL day is the time period between successive risings of a particular STAR on a fixed horizon on Earth. (The word “sidereal” means pertaining to a star.)
The Earth SIDEREAL day is slightly less than the Earth SOLAR day, due to the revolution of Earth round The Sun.
The Earth SOLAR day relates to The Earth SIDEREAL day by the following formula:-
[(1 ÷ 0.9972697) MINUS (1 ÷ 365.256)] = 1.0000000