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shelton
2008-Mar-16, 12:29 AM
I live in Colorado near Colorado Springs. The vernal equinox comes at 1:48 AM on the East cost on 20 March 2008. This means it comes on 11:48 PM in Colorado! This is 0548 UTC, so does this not mean that the first day of Springs in Colorado is 19 March and not the 20th?
Cheers,
Frank

01101001
2008-Mar-16, 12:47 AM
Welcome to BAUT Forum.


I live in Colorado near Colorado Springs. The vernal equinox comes at 1:48 AM on the East cost on 20 March 2008. This means it comes on 11:48 PM in Colorado! This is 0548 UTC, so does this not mean that the first day of Springs in Colorado is 19 March and not the 20th?

Indeed the vernal equinox (Wikipedia (http://en.wikipedia.org/wiki/Equinox)) occurs 0548 UTC, 2008 March 20 -- also known as 2348 MDT, 2008 March 19.

It seems pretty early this year (mostly thanks to that extra day in February).

In 2012 it will happen about 40 minutes earlier.

(No, I won't do the 2012-topic shuffle here. Unless I have to.)

grant hutchison
2008-Mar-16, 01:05 AM
Those early equinoxes are going to keep on getting commoner for the next century.
It's all because we had a leap year in 2000, whereas we skip the leap year in centuries that are not divisible by 400 (so there was no leap year in 1700, 1800 or 1900). The usual four-year cycle of leap years makes the calendar slide very gradually out of alignment with the seasons; the pattern of three skipped "leap centuries" every four hundred years is necessary to bring it back into alignment. The leap year in 2000 means the present slide will continue for another century, and then the omitted leap years in 2100, 2200 and 2300 will bring things back into alignment.

Grant Hutchison

grant hutchison
2008-Mar-16, 08:22 PM
This thread prompted me to rummage in Jean Meuss' Astronomical Tables of the Sun, Moon and Planets.
Over here on the Greenwich meridian, we've had our last March 21 spring equinox this century: it happened last year. From now until 2043, the spring equinox will fall on March 20, Universal Time. Our first March 19 spring equinox happens in 2044: the first spring equinox to fall on that date since 1796. March 19 equinoxes become more frequent thereafter, until the missed leap year in 2100 brings back the usual alternation between March 21 and March 20.

Grant Hutchison

hhEb09'1
2008-Mar-18, 03:51 PM
I live in Colorado near Colorado Springs. The vernal equinox comes at 1:48 AM on the East cost on 20 March 2008. This means it comes on 11:48 PM in Colorado! This is 0548 UTC, so does this not mean that the first day of Springs in Colorado is 19 March and not the 20th?
O no, this is going to play havoc with our national stand-an-egg-on-end effort! Can't we do something, like declare double-daylight saving time? I guess we'd need a triple, for the west coast.