Who decides when the first day of spring is?

Question

I have seen 2007 calendars that put the first day of spring on March 20, and others on March 21. Which is correct? I know spring starts on the vernal equinox, but who decides what that is?

Answer 1

An equinox is an astronomical event. It's when the Sun is directly above the equator. There are two every year: (1) The Vernal (Spring) when the position of the Sun is moving from South to North and (2) the Autumnal (Fall) when the Sun is moving from North to South.

For more information see the Wikipedia page that I put a link to under "Sources"

That has a table showing that this year the vernal equinox occurs at 00:07 on 3/21, which many people would call "seven minutes after midnight on 3/20". That's probably the reason for the confusion you mention.

Answer 2

No one decides what the vernal equinox is. It's an astronomical event. On December 21, the sun is directly overhead a point on the earth at a little over 23 degrees south latitude. As the earth orbits the sun, the tilt of the earth's axis causes the point directly underneath the sun to move northward. The vernal equinox is that moment when the sun is directly overhead a point on the equator. This usually happens on March 21 but can happen on March 20 or 22 also. The reason it jumps is leap year and the fact that the "tropical year" (the time between successive spring equinoxes) is more than 365 days long - it's 365 days 5 hours 49 minutes long.

Let's say that in 2000 the equinox is on March 21 at noon GMT. In 2001 it will be on March 21 at 5:49 p.m. On 2002 it will be on March 21 at 11:38 p.m. In 2003 it will be on March 22 at 5:27 a.m. In 2004 it would be on March 22 at 11:16 a.m., except for the insertion of leap day on February 29, 2004, which brings the equinox back to March 21 at 11:16 a.m. So in 4 years the equinox moves 44 minutes backward. This sort of variation lets the equinox occur on different days in March, and not always on March 21.

Let's say

Answer 3

The first day of Spring is marked by the Pagan festival of Imbolc that falls on February eve. i.e. January the 31st. Now that seems very early but bear in mind that spring goes on until May eve with the festival of Beltane. The Pagan year bieng divided into 4, 3 month seasons and based on the agricultural year.
March 20th is the vernal equinox and falls halfway through spring, it's when the clocks change. Pagans get to celebrate Imbolc and the equinoxes though festivals like Imbolc and Beltane are the mostt important. The festivals start with Samhain, then Imbolc, Beltane and finally Lughnassadh.

Answer 4

As a gardener I tend to count the weeks until the last expected frost date, April 15th here. That's about 11 weeks away. Then in mid-August, I'll start blocking out the weeks until the first expected frost date, October 21. But I know what you are getting at. I don't much like short days either. My body wakes up with the light. I'm looking forward to mid-February when I'll wake up naturally before 7:00 A.M.

Answer 5

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I'm counting right now and there are too many. (haha) After Christmas I start looking at the calendar to check sunrise and sunset times and wait as the days get longer. For me spring can't come soon enough. Oh, and I am in central Italy in the hills. Although it rarely snows it gets cold.

Answer 6

Well some calendar put it on the
day of the Equinox witch is the day spring starts. Other calendars put it as the first full day of spring.

Answer 7

no one does. it's just a date to help us realize when it's going to get hotter. like that works. when spring is near, the temps begin to rise. trees and grass grows. springs showers begin.

Answer 8

If your in the US, groundhog day, a concept I dont understand!