Sunset spots for equinoxes and solstices: montztermash
It’s equinox time. The 2014 March equinox comes tomorrow – on Thursday, March 20 – at precisely 16:57 Universal Time. That’s the standard time in Greenwich, England, and it marks a single time for this equinox as noted from a whole-Earth perspective – when the sun stands directly overhead as seen from Earth’s equator.
But, as always, our clocks will say different times. For the most of the United States, the equinox comes before midday (approximately 1 p.m. daylight-saving time) on March 20: 12:57 p.m EDT, 11:57 a.m. CDT, 10:57 a.m. MDT or 9:57 a.m. PDT. Meanwhile, the spring equinox will happen at sunrise in the Pacific Ocean (just west – or right – of the International Date Line), and at sunset in eastern Europe and Africa. One event – different time zones and different times on the clock – when the sun crosses the celestial equator, bring this equinox to all of us around the globe.
Day and night sides of Earth at instant of March 2014 equinox
Once again, translating Universal Time to local time in U.S. time zones, that places the time of the equinox at 12:57 p.m. EDT, 11:57 a.m. CDT, 10:57 a.m. MDT or 9:57 a.m. PDT on Thursday, March 20.
This event – which happens before midday for most of us in the United States – marks the first day of spring or autumn, depending on your location north or south on Earth’s globe. For the Northern Hemisphere, the March equinox marks the first day of spring. In the Southern Hemisphere, it signals the beginning of autumn.
The March equinox happens when the sun crosses the celestial equator from south to north. The celestial equator is a projection of the Earth’s equator onto the so-called celestial sphere.
This intersection point is sometimes called the First Point in Aries. But at this March equinox and all of those in our lifetimes, it happens when the sun is in front of the constellation Pisces. Over the long course of time, different constellations provide a backdrop to the sun as it soars above the Earth’s equator, going from south to north, year after year.
Over 2,000 years ago, the March equinox sun shone in front of the constellation Aries. Now the sun is in front of Pisces on the March equinox, and 600 years in the future, the March equinox sun will shine in the constellation Aquarius. It’s a 26,000-year cycle – Earth’s precession – that causes our vantage point on the stars to shift.
Image credit: Wikimedia Commons
By the way, according to the mathematical wizard Jean Meeus, the March equinox sun passed out of the constellation Aries and into the constellation Pisces in 68 B.C. Not until A.D. 2597 will the March equinox sun leave the constellation Pisces and enter into the constellation Aquarius.
Of course, the date on which the sun crosses a constellation boundary depends entirely on the location of that boundary. And the drawing of constellation boundaries is a human pursuit. The International Astronomical Union officially decided on the current boundaries of the constellations early in the 20th century.
So, wherever you are on Earth’s globe, celebrate this equinox, as the sun crosses the celestial equator, going from south to north!
Bottom line: The 2014 vernal equinox – spring equinox for the Northern Hemisphere, and autumn equinox for the Southern Hemisphere – on Thursday, March 20 at precisely 16:57 Universal Time. That’s the time from a whole-Earth perspective – when the sun stands directly overhead as seen from Earth’s equator. Meanwhile, our clocks say different times. For most of the U.S., the equinox takes place before midday (1 p.m. daylight-saving time) on March 20.