On Thursday, seasons changed when the vernal equinox occurred, marking the spring's official start of autumn in the Southern Hemisphere, and spring in the Northern Hemisphere.
Reports said, what happened was a rather fortunate occurrence-it was the earliest occurrence of the equinox across the whole of the United States in over 120 years. Specifically, the exact occurrence took place on Thursday evening at exactly 11:42 p.m.
At the time of the occurrence, an astronomy reference indicated, the Earth would "reach the point in its orbit from which the axis was not tilted away from or toward the sun." Consequently, the sun would then be directed over a particular point on the equator of the Earth moving towards north. Up in the sky, it was where the celestial and ecliptic equator "cross each other."
ALSO READ: Imaging the Wonderful Canadian Arctic Archipelago
The Earliest Occurrence of Spring in More Than A Century
For more than a century, the spring equinox had taken place, usually on March 20 or 21. However, this year, it happened on the 19th of the month across all American time zones, which made it the earliest spring seen in people's lifetime. Astronomy experts say, the last year spring happened this early was 1896 or 124 years ago, to be exact.
Obviously, this results in some vital questions such as Why the spring equinox came in a day or two, earlier this year; if the date would keep shift, this leads to some important questions, like Why the equinox so early this year; Will the date keep changing to earlier date each year; or if the equinox starts on March 21 after this year?
Why does the Equinox take place?
The equinox, the shifting length of daylight hours in the entire year, and the seasons are all because of one reality and that's the Earth is spinning on a tilted axis. The tilt, according to astronomy reports, is possibly caused by a huge object that hits the Earth billions of years ago.
This means that for half the year, "The North Pole is pointed" towards the direction of the sun. Then, for the other six months, the South Pole is receiving more light. This then, is what gives humans the seasons. Essentially, during March equinox, the sun is crossing the astronomic equator from south to north.
This movement is also known as the "celestial equator" as it depicts an imaginary line in the sky on top of the equator of the Earth. Say, a person is standing on the equator, the sun is seen passing straight overhead towards the north.
As mentioned, equinoxes take place every six months or twice a year. It happens when the sun rises due east, then it sets due west. And, when it passes above, the Earth's tilt is "zero relative to the sun." Meaning, the axis of the Earth neither points toward the sun nor away from it.
And finally, after the spring equinox, the Northern Hemisphere then tilts towards the direction of the sun-the reason why the day starts to get longer-also the reason for sunnier days.
