<P> On the day of an equinox , daytime and nighttime are of approximately equal duration all over the planet . They are not exactly equal , however , due to the angular size of the Sun and atmospheric refraction . The word is derived from the Latin aequinoctium , from aequus ( equal ) and nox ( genitive noctis ) ( night ) . </P>
<P> On the day of an equinox , daytime and nighttime are of approximately equal duration all over the planet . They are not exactly equal , however , due to the angular size of the Sun and atmospheric refraction . The word is derived from the Latin aequinoctium , from aequus ( equal ) and nox ( genitive noctis ) ( night ) . </P>
what is it called when day and night are equal length
what is it called when day and night are equal length
equinox
equinox