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Spring Equinox

March 20, 2014 by · Comments Off on Spring Equinox 

Spring Equinox, Google has marked the first day of spring with one of its famous doodles – in this case, a charming little blobman watering a handful of lovely flowers. Google’s chap obviously doesn’t live in England, which has suffered its wettest winter in 250 years and where the daffodils definitely don’t need watering.

But there’s also something curiously dated about announcing the start of spring after daffodils, crocuses and other buds of spring have been out for several months in some parts of the country. 20 March is the spring equinox which, in the astronomical system of seasons, is the first day of spring.

The date the spring and autumn equinoxes fall each year – the days are the ones when day and night are roughly the same length – fluctuates because of the Earth’s orbit around the sun.

Meteorological types, like the Met Office, prefer to use a temperature-based system, where spring is fixed every year – it officially starts on 1 March, and runs through to the end of May. (The Met Office has a good blogpost on the difference between the two systems).

However, both systems feel like they’ve not kept up with the times. As average temperatures have gone up due to climate change, studies have found British flowers came out between 2 and 12 days earlier in the past quarter century than in any previous 25-year period.

This year, traditional harbingers of spring, such as ladybirds and butterflies, and hazel and snowdrops flowering, appeared in early January. The winter, as well as being exceptionally wet, was also unusually mild, even by the standard of recent years.

Maybe next year, Google’s spring doodle will appear a couple of months earlier too.

Spring Equinox

March 20, 2012 by · Comments Off on Spring Equinox 

Spring Equinox, Across much of the United States, this has been an unusually mild winter, especially for those living east of the Mississippi. Not a few people have noted that spring seems to have come early this year. Of course, in a meteorological sense that could be true, but in 2012 it will also be true in an astronomical sense as well, because this year spring will make its earliest arrival since the late 19th century: 1896, to be exact.

The vernal equinox – the first day of spring – will arrive tomorrow (March 20) at 05:14 Universal Time, or 1:14 a.m. EDT. Even more intriguing is that for those in the Mountain and Pacific Time zones, the equinox will actually arrive tonight (March 19).

Astronomers define an equinox as that moment when the sun arrives at one of two intersection points of the ecliptic (the sun’s path across the sky) and the celestial equator (Earth’s equator projected onto the sky). One such intersection point is located in western Virgo; the sun arrives there on Sept. 22 or 23, and appears to cross the equator from north to south, marking the beginning of autumn in the Northern Hemisphere.

The other intersection point, in eastern Pisces, is where the sun will be tomorrow. The sun is now migrating north of the equator, hence this is the “vernal” or spring equinox. At 5:14 UT next Tuesday, the sun will be shining directly over the equator from the point of view of a spot in the Indian Ocean, 757 miles (1,218 km) southeast of Colombo, Sri Lanka.

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