The March equinox, also known as the spring equinox or vernal equinox, occurs on Monday, March 20, at 3:29 a.m. Tucson time.

At that very moment, the sun shines directly on the equator. Because the Earth moves around the sun completely once a year, the sun appears to move slowly across the sky from day to day. When the sun crosses directly over the equator from the southern to the northern part of the sky, winter officially gives way to spring.

If you are into celebrating this event, get up well before sunrise (6:27 a.m.) Monday morning and look at the southern sky. At 5:30 a.m. the last quarter moon sits only 2½ degrees above Saturn.

Just below the moon and Saturn is the “teapot” grouping of stars representing Sagittarius the Archer. To the right (west) of Sagittarius is Scorpius the Scorpion with bright red Antares at the heart of the Scorpion.

At the March equinox, around March 21 and the autumnal equinox around Sept. 21, every year, the hours of daylight and nighttime are about equal. Equinox means “equal night.” For Tucson’s latitude of about 32 degrees north, the times of equal daylight (from sunrise to sunset) and night (from sunset to sunrise) are five to six days before March 21 and five to six days after Sept. 21.

Contact Tim Hunter at

skyspy@tucson.com