Thursday is the first day of spring, or the vernal equinox, in the Northern Hemisphere. During an equinox, the center of the sun is on the same plane as the equator. After the vernal equinox in March, the Northern Hemisphere tilts toward the sun until the June solstice, when the sun begins to migrate back south.

Spring equinox means the first official day of spring is here. Discover the science and traditions of what’s also called the vernal equinox..