Earth's Seasons

Earth's seasons — winter, spring, summer and autumn(or fall) — are caused by the yearly revolution of the Earth in its orbit around the sun and the planet's tilt. When the Northern Hemisphere is pointed toward the sun, it is summer, and when it is pointed away, it is winter (and vice versa for the Southern Hemisphere). Summer and winter are heralded by their respective solstices, while spring and fall begin at an equinox, when the sun crosses Earth's equator and night day are roughly equal length. Below, our stories that relate to Earth's seasons and the ways they affect us.
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The Mystery of Why Urinary Tract Infections Peak in Summer
artist rendering of bacteria
October 27th, 2015
Severe urinary tract infections spike in the summertime, especially among younger women, a new study finds.
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Deadly Gut Bacteria Infections Peak in Spring
April 29th, 2015
Infections with difficult-to-treat and sometimes deadly gut bacteria called "C. diff" are highest in the spring, according to a new study.
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How to Choose a Sunscreen That Protects You
A woman wearing sunscreen on her back in the shape of a smiley face.
June 17th, 2015
You know you should wear sunscreen, but do you know what to look for in a sunscreen?
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Why Spring Gets About 30 Seconds Shorter Every Year
people in a park in San Francisco
March 19th, 2015
Spring arrives on Friday, and you might want to make the most of it. The season of flowers and showers actually gets shorter every year by about 30 seconds to a minute, due to astronomical quirks, researchers say.
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Snowvember: What's Causing the Unseasonably Cold Weather?
Satellite image of Typhoon Nuri.
November 13th, 2014
The polar vortex isn't the only weather system to blame for your frozen fingertips.
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Solstice Science: How Humans Celebrate Official Start of Summer
Summer Sun
June 20th, 2015
This Sunday (June 21) marks the summer solstice, the official start of summer in the Northern Hemisphere.
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Spring Colors Swirl in Picturesque North Atlantic
Plankton in northwest Atlantic Ocean
May 27th, 2015
A new NASA image hints at the complex factors that encourage giant plankton blooms in the North Atlantic.
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5 Weird Ways Cold Weather Affects Your Psyche
Women in cold snow
March 11th, 2015
Freezing temperatures and snow have turned much of the United States into an icebox. But, beyond keeping people inside and prompting them to bundle up when they venture out, does the cold weather change people's behavior?
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