Our long, hot summer is finally coming to an end on Tuesday, Sept. 22 with the autumnal equinox, which marks the beginning of fall in the Northern Hemisphere.
At a precise moment each September, on either the 21st, 22nd or 23rd, the sun is directly above the equator, marking the exact time of the autumnal equinox here in the Northern Hemisphere.
There are two equinoxes every year – in September and March – when the Sun shines directly on the Equator and the length of day and night is nearly equal.
Below the equator in the Southern Hemisphere, it’s known as the vernal or spring equinox and marks the beginning of spring. So if you’re in need of more guaranteed warmth and sunshine in the months ahead, head way down south to countries such as Argentina, South Africa or Australia.
(It’s true that day and night aren’t exactly 12 hours long on the day of the equinox because the Earth’s atmosphere refracts, or bends, light in an optical illusion that brings more daylight than there really is. Because of this, the date when day and night are of equal length is usually a few days after the autumnal equinox.)
Although some people claim that the autumnal equinox is the “official” start of fall, there is no administrative or political organization that actually designates that.
Indeed, though astronomers say summer ends Tuesday, meteorologists and climatologists said summer ended Aug. 31, the final day of the three hottest months of the year (June, July and August).