Every year around March 20, the equator aligns with the sun, and for a moment, day and night are equal. In the Northern Hemisphere, this is called the spring or vernal equinox, and it marks the exit of winter into the brighter, warmer springtime. A sharp eye might spot a flowering crocus, shown in today's image, one of the first flowers to bloom every year. The tilting of Earth on its axis makes the equinox a truly global event. In Japan, spring equinox is a national holiday called Shunbun no Hi, while in Iranian culture, it is the start of the new year, called Nowruz. However, in the Southern Hemisphere, autumn is just beginning—so send some sweaters to your Argentinian friends.