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.

The equinox happens twice a year - in March and in September. Wherever you are on the planet, the equinox occurs at the same moment. For those south of the equator, where the seasons are reversed, the event will mark the first day of autumn.

The vernal equinox heralds the arrival of spring in the Northern Hemisphere (finally). But have you heard the myth about balancing an egg on its end?