The 'Summer Solstice' marks the longest day of the year; what astronomical term describes the two times a year when day and night are nearly equal in length?

Equinox

The term equinox comes from the Latin words for "equal" and "night," reflecting the near-perfect balance of daylight and darkness across the globe. These events occur twice a year when the Sun is positioned directly above the Earth's equator. A unique feature of the equinox is that it is the only time the sun rises exactly due east and sets exactly due west for everyone on Earth.