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Happy First Day of Fall

It's time to welcome in crisp temperatures and crunchy leaves

Related:Earth

• By Discovery
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  Get prepared: It's time to kiss long days and warm weather goodbye and welcome in crisp temperatures and crunchy leaves. The first day of fall, also known as the autumnal equinox, is Saturday, Sept. 22.
  
  The equinox gets its name from an astronomical curiosity. During both the spring and fall equinoxes, the sun transits directly over the Earth's equator. Day and night are approximately equal length on equinoxes, which is how the days got their name - it means "equal night" in Latin.
  
  PHOTOS: Why Do Leaves Change Color?
  
  This year's equinox occurs at 6:49 a.m. EDT (14:49 UTC) on Saturday, the time when the sun makes its pass over the equator. The actual date of the fall equinox varies slightly each year, sometimes falling on the 23rd or 24th depending on the vagaries of our calendar and Earth's slightly irregular orbit.
  
  While day and night both last about 12 hours around the equinox, the days will start to shorten in the Northern Hemisphere as winter approaches. That's because the Earth orbits at a slight tilt of 23.5 degrees. When the Northern Hemisphere tilts toward the sun, that half of the world experiences summer while southerners get winter. When the Northern Hemisphere tilts away, the seasons flip. (50 Amazing Earth Facts)