Today’s the first day of spring, otherwise known as the spring equinox. But what is an equinox, exactly? The answer lies in the tilt of the Earth’s axis. When it’s winter in the Northern Hemisphere, those of us above the equator are tilted away from the sun, giving us shorter days and longer nights. In summer, we’re tilted toward the sun, so we can enjoy longer days and shorter nights. But the equinox is right in between. It"s the moment during Earth"s annual revolution around the sun when its axis is neither tilting away nor tilting toward the sun, giving everyone on the planet an equal split of day and night. This phenomenon happens twice a year—in March and again in September. For folks in the Northern Hemisphere, today signals a shift toward the long days of summer. But in the Southern Hemisphere, everything"s flipped. It"s the autumnal equinox today—and, yes, winter is coming.
Hello, spring!
Today in History
More Desktop Wallpapers:
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National Love a Tree Day
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Green fields of grain
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Vietnam’s new bridge deserves a big hand
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Taking the scenic route to Sturgis
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Let’s have a ball
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Manatees rebound
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Whoopin it up!
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On the Route of the Waterfalls
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The largest living organism on Earth
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Heavens Gate Cave, Tianmen Mountain National Park, China
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Wedded Rocks, Japan
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Dancers perform ‘Revelations’
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Earth Science Week
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Through an artist s eyes
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Here, fishy!
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Nakupenda Beach Nature Reserve, Zanzibar, Tanzania
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Henningsvær Stadion, Norway
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World Teachers Day
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The lemurs of Madagascar
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That bill s just not going to fit
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International Ice and Snow Sculpture Festival, Harbin, China
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Aw shucks, It s Oyster Day
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Papa was a flightless bird
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Terraced rice fields, Yuanyang County, China
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Let’s go foraging
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Celebrating National Park Week, April 21-29
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Birds of the Drömling
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A shell of many colors
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Baddest of the badlands
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Why does this panda cub look so happy?