Autumn equinox is at 4:44 pm ET on Sunday, September 22. Officially marking the kick off of the fall season in the northern hemisphere and the start of spring in the southern hemisphere.
The word equinox comes from Latin meaning “equal night” and refers to the 12 hour long day and night that occurs only twice a year, spring and autumn.
It is only on the spring and autumnal equinox that the Sun rises due east and sets due west. However TimeandDate.com writes: during the autumn equinox the lengths of night and day are nearly, but not entirely, equal. Their reasoning is the sun takes longer to rise and set in places farther away from the equator.
The sun moves in a horizontal direction taking longer to rise and set farther from the equator, simply put, the sun does not set straight down. Also, the atmospheric refraction causes the sun to appear higher in the sky than it would if earth had no atmosphere.
September equinox is one of the four turning points in the cycle of seasons. It is on these turning points the Earth’s axis is neither tilted away nor towards the Sun, as both northern and southern hemispheres experiencing equal amounts of sunshine. The location on the earth where the sun is directly overhead at solar noon is known as the subsolar point; and only occurs on the equator during the September equinox and March equinox. At that time, the earth’s axis of rotation is perpendicular to the line connecting the centers of the earth and the sun. (The Earth spins on its axis, which is tilted at 23.5 degrees.)
A wonderful reference tool for finding Autumnal Equinox – Fall Equinox facts is timeanddate.com http://www.timeanddate.com/calendar/autumnal-equinox.html be sure to investigate timeanddate.com for astronomy calculators, calendar and time zone tools and more.
Some must see links on timeanddate.com are:
- Seasons Calculator
- Moon Calculator – Find times for moonrise, moonset and more
- Moon Phase Calculator – Calculate moon phases for any year
- Sunrise Calculator – Find times for sunrise, sunset and more
- Day and Night World Map – See which parts of the Earth are currently illuminated by the Sun
Another resource for families is: EarthSky. http://earthsky.org/astronomy-essentials/everything-you-need-to-know-september-equinox this site has science news, fantastic photos, your family can even receive sky alerts.
The Autumn Equinox: Celebrating the Harvest by Ellen Jackson is a wonderful family read. Showing the universal phenomenon of giving thanks at harvest. From Africa and the Far East, to Canadians and Americans, each society has devised a way to offer thanks at harvest.
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