Question

What is solstice and equinox

Answer 1

A solstice is an event occurring when the Sun appears to reach its most northerly or southerly excursion relative to the celestial equator on the celestial sphere. Two solstices occur annually, around June 21 and December 21.

An equinox is commonly regarded as the instant of time when the plane of Earth's equator passes through the center of the Sun. 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.