An incredible satellite image shows what the spring equinox on Earth looked like from space.
Equinox actually means “equal night” in Latin, and it happens twice a year in March (vernal) and September (autumnal), when the length of day and night are almost equal at all latitudes.
This only happens twice a year because Earth is tilted on its axis at a 23.5-degree angle, which means the Earth is illuminated unequally and, depending on where Earth is on its orbit, either the Northern or Southern Hemisphere will have longer days or nights.
During the equinox, however, the Earth’s tilt is perpendicular to the Sun, meaning our planet gets bathed in sunlight and is hidden in shadow equally for 12 hours all over the world. The perfect vertical line here is because Earth’s axis is neither pointing toward nor away from the Sun – something that is very short-lived.
NOAA’s Geostationary and Polar-Orbiting Weather Satellite, GOES East, snapped the photo from its position 35,400 kilometers (22,000 miles) away on March 20, at 8am EDT, just prior to the equinox that occurred at 5.58pm EDT.
The equinoxes mark the point when the Sun shines directly on the equator, which means it's directly overhead at noon. The nearly equal hours of the day and night are due to the refraction of sunlight (the bending of the light’s rays) that causes the Sun to appear above the horizon when it is actually below it.
Of course, this wasn't just any spring equinox. March 20 also saw the third, and last, supermoon of the year in the Super Full Worm Moon – the first time there's been a full moon on the same date as the spring equinox since 1981. Even rarer there hasn't been a supermoon this close to the vernal equinox since 1905, and there won't be another again until 2144.