Today, March 20, 2025, at 10:01 the spring equinox takes place. Let’s review together some curiosities about this astronomical event that marks the change of season.
Today, March 20, 2025, at 10:01 (Italian time), the spring equinox officially starts. But be careful, all this applies to the northern hemisphere of the earth, because in the southern one the event marks the end of summer the beginning of autumn. It is the time, that is, in which the sun crosses the vernacular. But what else does it happen, precisely?
The same night and day? Almost…
The equinox is the day when, theoretically, the day and night should have the same duration (Exactly 12 hours). However, due to the atmospheric refraction and the way we measure the dawn and sunset, the day is slightly longer than the night.
The “terminator” (what ???) is perfectly vertical
The terminator It is the imaginary line that divides the Illuminated part of the earth from the one in the shade. During the equinox, this line connects exactly the two poles, being perfectly vertical. In the following days, it will tilt more and more, bringing more light and heat to the northern hemisphere.
The sun at noon is perfectly to the Zenit to the equator
If you were at the equator today, you would see the sun exactly above your head at noon, without shadows projected to the ground.
But didn’t they say at school that spring start on March 21?
Traditionally at school they taught us that spring began on March 21, but in reality, due to the discrepancies between the calendar year and the calendar Gregorianthe equinox often falls on the March 20 And, in some cases, it can also slip to 19.
