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How Many Equinoxes Do We Have in a Year?

The word "equinox" means "equal night," according to the National Maritime Museum in London, England. The equinoxes mark the dates in spring and autumn when daytime and nighttime are equal, due to the changing alignment of the Earth and Sun.

Time Frame
- Earth has two equinoxes per year, according to the National Maritime Museum. The first is the vernal equinox that occurs in March, and the second is the autumnal equinox that occurs in September.
Orientation
- The Earth rotates on an axis, which makes daytime and nighttime unequal most of the year. Twice a year, when the Earth seems to sit up straight instead of leaning on its axis, the Sun hits the equator for the equinoxes. This makes daytime and nighttime each 12 hours long.
Fun Fact
- The equinoxes do not always occur on the same dates every year. The Earth does not revolve around the Sun in exactly 365 days, as the calendar would have people believe; instead, it takes 365 days and a quarter. This means that every four years, equinox dates are pushed back one day to make up for the annual six-hour delays.

Astronomy