Spring street banners go up along Central Avenue Tuesday marking the first day of spring. Photo by Carol A. Clark/ladailypost.com

Tuesday marked the first day of spring – the vernal equinox – when day and night are each approximately 12 hours long (with the actual time of equal day and night, in the Northern Hemisphere, occurring a few days before the vernal equinox.)

This is when the Sun crosses the celestial equator going northward; it rises exactly due east and sets exactly due west, according to the Old Farmer’s Almanac.

Spring brings increasing daylight, warming temperatures, and the rebirth of flora and fauna.

The word equinox is derived from the Latin words meaning “equal night.”

The spring and fall equinoxes are the only dates with equal daylight and dark as the Sun crosses the celestial equator.

At the equinoxes, the tilt of Earth relative to the Sun is zero, which means that Earth’s axis neither points toward nor away from the Sun.

However, the tilt of Earth relative to its plane of orbit, called the ecliptic plane, is always about 23.5 degrees.

Photo by Carol A. Clark/ladailypost.com