An equinox is the moment the Earth’s equator crosses the center plane of the sun. During an equinox, the northern and southern hemisphere are equally illuminated by the sun. The word equinox comes from the Latin equi meaning “equal" and nox meaning “night.”
The spring equinox is known as the vernal equinox and happens in March.
The autumn equinox is known as the autumnal equinox and happens in September.
In summer and winter there are solstices, the times when the sun reaches it’s most northernly or southernly peak from the equator.
This year, the equinox and solstices will occur on the following days:
Vernal Equinox: March 20, 2018
Summer Solstice: June 21, 2018
Autumnal Equinox: September 23, 2018
Winter Solstice: December 21, 2018
