The reverse is true south of the equator, meaning the seasons are reversed.
Between the two solstices, the equinoxes mark the start of spring and autumn.
These are the spring or vernal equinox and the autumn equinox.
Astronomers at the Royal Observatory Greenwich said: “At two points in the year the Sun will illuminate the northern and southern hemispheres equally.
“These are known as the equinoxes: the autumnal equinox and vernal or spring equinox.”
The name equinox comes from the Latin words “aequus” or equal and “nox” or night.