What is the equinox? How many times does it happen in a year? Today is the autumn equinox and let me tell you why it is 2 days late. Special for equinox days E-commerce sites operating in our country carry out various campaigns. now back to the topic. Equinox; It is the situation where the day and night are equal as a result of the sun's rays hitting the equator perpendicularly, known as the equality of day and night. It repeats itself twice a year as Spring Equinox and Autumn Equinox. Do you know the reason why the equinox, which should be experienced on September 21, happened on September 23? Since the Earth's orbit is elliptical, the Earth gets closer to the sun from time to time and moves away from time to time. The closest to the sun is January 3, and the farthest is July 4th. As the earth gets closer to the sun, the gravitational force of the sun also increases, thus increasing the speed of the earth in orbit. As the earth moves away from the sun, the earth's orbital speed decreases as the sun's gravitational force decreases. It's summer for the Northern hemisphere when the Earth's movement begins to slow down. Summer is two days longer in the Northern Hemisphere, as the speed of the Earth decreases as the Earth moves away from the sun. The September equinox occurs on September 23, with a delay of 2 days, due to the decreasing speed of the Earth in orbit.