Equinoxes are moments when day and night are of equal length. They occur twice a year and happen when the sun is exactly above the equator. On this day every area of our planet experiences approximately the same amount of daylight and darkness. This occurs twice a year. These are called the vernal equinox and the autumnal equinox. Today is the vernal equinox. In the northern hemisphere it marks the beginning of spring. On the other hand the autumnal equinox marks the beginning of autumn in September (in the northern hemisphere). Along with the two annual solstices, the two equinoxes mark the change in seasons.
Watch the following videos to learn about the spring equinox:
https://www.youtube.com/watch?v=HG5bEcttTm4
https://www.youtube.com/watch?v=CSs8K_HQSZ4
https://www.youtube.com/watch?v=enlih8M5DN0&t=11s
