Autumn equinox 2016: What is it; when is it?

If you are going to enjoy summer 2016, you better hurry.

It’s over on Thursday at 10:21 a.m. (ET). That’s when the autumn equinox happens.

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What's an equinox? The equinox triggers autumn on calendars in the northern hemisphere and marks the day when the sun will shine, almost directly, over the Earth’s equator.

What does that mean? Here are a few autumnal equinox facts:

1. The word “equinox” comes from the Latin word meaning “equal night.” It refers to the roughly equal amounts of daylight and night time that happens on Thursday.

2. An equinox happens when there is an alignment between the sun and Earth in which the sun appears positioned directly above the Earth’s equator.  During the autumn equinox – and the spring one – the sun rises due east and sets due west.

3. There is ancient Maya step pyramid – El Castillo at Chichén Itzá in Mexico – where at sunset on the equinox sunlight hits the building’s staircase and creates a snake-like shape that appears to slither up the stairs.

4. From Sept. 22 onward, the days will get shorter until the Winter Solstice in December (less sunlight each day).

5. As far as meteorologists are concerned, the first day of autumn was Sept. 1. They mark meteorological seasons on Sept. 1, Dec. 1, March 1 and June 1.

Sources: National Geographic; Encyclopedia Britannia; The Weather Channel

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