Category: Tech / Sci / March 20, 2013 5:20 PM EDT
Spring is here. And so is the Spring Equinox. Or is it the solstice?
Equinoxes occur twice a year. The one in March is also referred to as the Vernal equinox, the one in September the autumnal equinox. Simply put, it’s the day during which the sun rises and sets directly above the equator. To better understand why this phenomenon occurs and what it signals, it helps to understand how the Earth rotates around the Sun. Rather than circling the Sun at a right angle the Earth’s rotational axis has a 23.5 degree tilt relative to the Sun. This means that for half of the Earth’s rotation or half the year either the northern or southern hemispheres are tilted towards the sun, warming that region and resulting in the changing seasons. The equinoxes are those two times during the year when neither the northern or southern hemispheres are tiled towards the sun. For about a day both the northern and southern hemispheres receive the same amounts of sunlight.
The shift by the earth means the Northern hemisphere will start receiving more sunlight and gradually grow warmer until June 21st, the Summer solstice, when the tilt of the Earth reaches its zenith and the Southern hemisphere again begins tilting closer to the sun until the Fall equinox when the Northern hemisphere begins to tilt back towards the sun and so on and so on.
So, if you’re not aware IT’S NOW SPRING IN THE NORHTERN HEMISPHERE AND FALL IN THE SOUTHERN.
But, you probably knew that already.
Thumbnail: Flickr user bowtoo