Do the spring and autumn equinoxes give us days and nights of the same length? It isn’t so simple, says Abigail Beall in this month’s Stargazing column
17 March 2021
THIS Saturday (20 March) marks the vernal – or spring – equinox, when the sun crosses the celestial equator, sitting exactly between the hemispheres. It also marks the start of spring in the northern hemisphere and the beginning of autumn in the southern hemisphere.
You might have heard that day and night are of equal length around the world at the equinox (hence the name), but this isn’t strictly true. In an equinox, there are around 12 hours of daylight and 12 hours of night, but most places on Earth will receive slightly more daylight (see table).