Spring has sprung

An event of astronomical importance just occurred:

Spring arrived at 1:48 a.m. Eastern Daylight Time.

That's the exact moment the sun's rays fall directly on the equator as the tilted Earth comes back around to where it again starts to lean its northern hemisphere toward the sun.

Today, the hours of daylight will equal those of dark — "equinox" means "equal night" — and that evening the sun will set exactly due west.

Friday, the moon will be full, and because Easter is the first Sunday after the first full moon that follows the vernal equinox, this Sunday will be an unusually early Easter.

Like the sun's crossing the Earth's equator at a specific time, so also does the moon's face fully emerge into sunlight at an exact moment — 2:40 p.m. Friday.

"That's the unusual part," said Shawn Cruzen, director of Columbus State University's Coca-Cola Space-Science Center. "The vernal equinox technically is an instant of time, and so is the full moon, and to have them within almost 24 hours of each other like that, that is unusual."

Most folks measure the seasons by their calendars, and note the coming of spring by warmer weather, longer days and blooming flowers. Others follow the sun.

"The vernal equinox is one of four kind of critical points in the position of the sun in the sky," Cruzen said. The other three are the summer solstice, the year's longest day; the winter solstice, the year's shortest day; and the autumn equinox when again day and night are of equal length.

If you like to judge direction by where the sun rises and sets, today's the day to double-check, because east is east and west is west — truly: "Sunrise is due east and sunset is due west only on the equinoxes," Cruzen said.