Science What exactly is an equinox, anyway?

As Sunday ushered in the first official week of autumn, with the autumnal equinox setting Earth's Northern Hemisphere on a path to shorter days and colder temperatures. But what does the equinox really signify, and what's actually happening in the night sky? We break it down for you.

By , Contributor

Sunday's equinox marked the transition from summer to autumn in the Northern Hemisphere and from winter to spring in the Southern Hemisphere. Here, we answer your most pressing equinox-related questions.