The spring equinox 2023, which marks the beginning of the season in the northern hemisphere, takes place on Monday March 20 and not on the 21st, as is often expected. See why.
This year, spring will officially begin Monday at 5:24 p.m. Quebec time, according to NASA.
What is an Equinox?
The Earth, which is tilted, takes a day and a night to turn on itself, and a year to turn around the Sun.
The equinox therefore corresponds to the moment when the Sun is at its highest point in relation to the equator, that is to say at a point located vertically above our heads. On that day, the day and the night last exactly the same number of hours and the two hemispheres receive as many solar rays.
A calendar problem
To measure days, months and years, most of us use the Gregorian calendar which divides a year into 12 months. However, the Earth actually takes 365.2422 days to revolve around the Sun. Each year therefore ends with a quarter of a day less than its actual duration, hence the decision to have a month of February which has 29 days every four years.
These variations also have the effect of changing the day of the equinox.
It will be necessary to wait until 2102 for the spring equinox to fall again on March 21. The autumnal equinox is also affected and should not arrive on September 21 before 2092.
What to expect for 2024?
For the first time since 1896, spring 2024 will fall on March 19. It is also one of those years where February will be a leap year, so will have 29 days, thus shifting the equinox by an extra day.
“Consider July a hot summer month where you live. If we never had a leap year, all those lost hours would add up to days, weeks and even months, NASA has detailed. After a while, hundreds of years from now, July would become a cold winter month [pour l’hémisphère nord].”