EDMONTON -- Spring keeps getting earlier and earlier.
It's happening slowly but the equinox keeps shifting earlier into March.
So, although most people just assume spring starts on March 20 or 21 every year, in the 2000s we have to get used to it starting on the 19th or 20th.
Why?
Well… the short answer is leap years. But, not ALL leap years. Specifically, the ones that sometimes occur at the start of a century. WHEN (and only when) that year is divisible by 400, you get a February 29.
2000 WAS one of those years. 1900 was not.
More on that in a minute…
The equinox is actually an exact time.
At 9:49 p.m. on Thursday, March 19, 2020, the earth's north/south axis won't be tilted toward or away from the sun.
In fall and winter (for the northern hemisphere), the earth's axis is tilted away from the sun.
In spring and summer, it's tilted towards the sun.
But on the equinoxes, the sun's most direct rays are right over the equator.
(Side note: the equinox doesn’t actually mean equal day and night for Alberta. That 12/12 breakdown occurs on a different date.)
Back to leap years...
We all know that we get an extra day in February every four years to help adjust the calendar and keep it in line with the solar year.
But did you know that doesn't happen EVERY four years?
The extra day every fourth February STILL leaves us slightly out of whack with the solar year.
So a rule was made to ONLY include a leap day on century years that are divisible by 400.
Again: 1900 wasn't. But 2000 WAS.
This has caused us to slowly slip "backwards".
The equinox gets later each year and then “jumps back” on the next leap year. 2004’s equinox is of half an hour earlier than 2000’s.
They're ALL on the 19th now.
And... they're getting earlier.
So by 2060, we'll have the equinox early in the afternoon of the 19th.
