Canada will see earliest spring in 120 years. Here's why

Friday, March 18, 2016, 10:52 AM - Spring is this Sunday, March 20 and this year marks the earliest vernal equinox since 1896.

The equinox occurs at exactly 4:30 UTC on March 20 for the entire planet, however, due to the way we track time, Canadians will be split on when the first day of spring actually occurs. Roughly half the country gets to leave winter behind on March 19, since 4:30 UTC is before midnight for the Central, Mountain and Pacific time zones. Meanwhile, the rest of the country - those in the Newfoundland, Atlantic and Eastern time zones - will see spring start in the early morning hours of March 20, as the Sun crosses the equator after midnight for those regions.

The sun starts to rise earlier and sets later in the day. Flowers start to bloom and warmer weather returns. Meanwhile, for the southern hemisphere, this is the moment of the autumnal equinox.

Why spring is so early in 2016? The answer is leap years.

Humanity started following the Gregorian calendar in the 1500s, which tells us that one year (the time it takes for Earth's annual revolution around the sun) is equal to 365 days exactly. This occurs unless there is a leap year, which brings the total number of days to 366. Leap years allow us to keep the seasons balanced.

However, there are two exceptions. The first is that there are no leap years at the turn of the century. Although the years 1700, 1800 and 1900 fell within the usual four year cycle, they were not leap years. This was and continues to be the case unless the century is divisible by 400. For example, we had a leap year in 2000 but skipped the one in 1900.

"Our calender system is set up in a 400 year cycle so that it makes up for all the little fractions that are left over since Earth doesn't spin in 365 and a quarter days," astronomer Bob Berman who runs the Overlook Observatory in New York told Business Insider. "What this tends to do is make leap days reset themselves so that the equinoxes and solstices all happen [on schedule]."

Berman explains because the year 2000 was a leap year, "instead of everything being reset so that all dates of the equinoxes and solstices get knocked back to their usual dates... that did not happen."

As a result, the first day of spring will come earlier throughout this century.

Want to know more about the vernal equinox?

Tune into a special presentation below hosted by Slooh on March 19 at 5 p.m. ET.

SOURCE: Business Insider

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