Equinox

astronomy · Earth · seasons · Sun

Balanced day and night. During an equinox, almost everywhere on Earth gets about 12 hours of daylight and 12 hours of darkness. This happens because the Sun is positioned right above the equator, shining equally on the Northern and Southern hemispheres.

Two times yearly. Equinoxes happen around March 20 and September 23 each year. The spring (vernal) equinox arrives in March in the Northern Hemisphere, while the fall (autumnal) equinox comes in September.

Perfect east-west sunrise. On the day of an equinox, the Sun rises almost exactly in the east and sets almost exactly in the west everywhere on Earth. This straight path happens because the Sun is directly above the equator.

The word's meaning. Equinox comes from two Latin words: 'aequus' meaning equal and 'nox' meaning night. It perfectly describes a day when light and darkness are nearly equal.

Marks season changes. The equinoxes are the official starts of spring and fall in both hemispheres. They're nature's way of announcing that the seasons are shifting and the year is turning.