Vernal Equinox 2012 Starts Tuesday
The vernal equinox is tomorrow and has some people wondering what exactly it is other than the official start of spring.
The vernal equinox starts on Tuesday morning at 1:14 a.m. EST. But those in Mountain and Pacific Time zones will actually see the equinox arrive one day before on March 19.
Astronomers explain that the equinox is the moment when the sun passes one of two intersection points of the suns orbit, known as an ecliptic orbit, and the celestial equator, Earth's equator.
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On Tuesday the sun will be directly over the equator from the point of view of a place in the Indian Ocean, 757 miles southeast of Colombo, Sri Lanka, according to SPACE.com.
Another important circumstance surrounding the equinox is that it marks a day that sees equal time of day as well as night, but as meteorologist Joe Roa explains that is actually an illusion.
As Rao explains the calculations of sunrise and sunset times made by the U.S. Naval Observatory have used different calculations to incorporate the curvature of the Earth and the time differential created by the Earth's shape.
Rao states that as a person watches the sun either rise or fall that the person is actually looking at an illusion. This is due to atmospheric refraction from the way in which light bends as it passes around the Earth's atmosphere.
The sun's light is pulled around the curvature of the Earth so when light breaks the horizon it is only the light and not the sun that is seen.
For those who are able to catch the sun at either of those times they will see the sun for a few minutes before the sun actually rises and for a few minutes after it has set. This adds about six minutes of daylight to the average day.
