Question

What is an equinox and when does it happen?

Answer 1

An Equinox is commonly regarded as the instant of time when the plane of Earth's equator passes through the geometric center of the Sun's disk. This occurs twice each year, around 20 March and 23 September. In other words, it is the moment at which the center of the visible Sun is directly above the equator.

Step-by-step explanation:

Answer 2

An equinox is commonly regarded as the instant of time when the plane (extended indefinitely in all directions) of Earth 's equator passes through the center of the Sun. This occurs twice each year: around 20 March and 23 September.