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Do You Realize The First Day of Spring Was Today---March 20, 2011 ?

From Lithonia, Georgia

 

 

 

Do You Realize The First Day of Spring Was Today---March 20, 2011 ?

By Connie Johnson, Killen, Al. Local News Editor,

Wow just last weekend we lost an hour, as Daylight Savings Time started. Guess what people, today was the first day of Spring. If you blink your eyes too many times,  it will be next year. Time waits for no one, soo get your motors charged as fast as you can, because summer is right around the corner.

In the Northern Hemisphere spring officially begins at 7:21 p.m. ET on Sunday, March 20, 2011—the vernal equinox, or spring equinox.

But don't be fooled by the old rumor that on the vernal equinox the length of day is exactly equal to the length of night.

The true days of day-night equality always fall before the vernal equinox and after the autumnal, or fall, equinox, according to Geoff Chester, a public affairs specialist with the U.S. Naval Observatory in Washington, D.C.

"Exactly when it happens depends on where you are located on the surface of the Earth," he said.

By the time the center of the sun passes over the Equator—the official definition of equinox—the day will be slightly longer than the night everywhere on Earth. The difference is a matter of geometry, atmosphere, and language.

Astronomical spring in the Northern Hemisphere as defined by the International Astronomical Union begins with the Vernal Equinox on March 20, 2011, at 7:21 p.m. EDT.

At the start of spring (spring equinox), day and night are approximately 12 hours long (at the equatorial plane) and the Sun is at the midpoint of the sky. Our north pole tilts towards the Sun.

In general, the four seasons correspond to the relative position of the sun to the earth. Meteorological determination of spring is calculated according to when the sun passes through the equatorial plane. When going from winter to spring, the sun is moving north; as soon as the sun crosses the equator, we call it spring. (This applies to places north of the equator.)

The first day of spring in the Southern Hemisphere "official" date of spring south of the equator (official is corresponding to the first day of fall in places north of the equator) will be around September 20/21, depending on when the sun crosses the equator.

Countries such as Australia and New Zealand, however, designate the first day of September as the official first day of spring (climatological counterpart). Preference between these two methods varies across Europe. Many east Asian countries use lunar dates to determine the beginning of spring. 

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