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Solar Eclipse Facts: 14 Fascinating Things Skywatchers Should Know

Posted: Updated: 05/18/2012 12:30 pm

How savvy are you about solar eclipses?

You already know that eclipses like the one that will be visible in the U.S. on Sunday occur when the moon passes briefly between the Earth and the sun. You may also know that it's unwise to look at a solar eclipse with unshielded eyes. But while those practicalities are important, they pale in comparison to the fascinating scientific underpinnings of solar eclipses.

Did you know, for instance, that solar eclipses occur on a strict schedule, with similar total, annular, or partial eclipses occurring once every 6,585.32 days? That span of time, known as a saros, is how long it takes after one eclipse for the sun, moon, and Earth to be in the same relative positions to trigger another. And this strict adherence to the so-called Saros Cycle is just one of many fascinating but little-known facts about eclipses.

Want to learn more fascinating facts about solar eclipses? In the slideshow below, adapted from materials assembled by NASA scientist Dr. Sten Odenwald, you can click through 14 more...


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  • How savvy are you about eclipses? You probably know that a solar eclipse occurs when the moon passes between the Earth and the sun. But did you know that the shadow of a solar eclipse travel at 1,100 miles an hour at the equator and up to 5,000 miles an hour at the poles? And that's just one of this slideshow's fascinating facts, as compiled by NASA scientist Sten Odenwald. Picture taken on Easter Island, 3700 km off the Chilean coast in the Pacific Ocean, on July 11, 2010.

  • During an eclipse, local animals and birds often prepare for sleep or behave confusedly. Picture taken in Bucharest, Romania on January 4, 2011.

  • Before the advent of modern atomic clocks, studies of ancient records of solar eclipses allowed astronomers to detect a 0.001 second per century slowing down in Earth's rotation. Picture taken on July 22, 2009 from the observatory of the University of the Philippines in Manila.

  • The width of the path in which a total eclipse is visible is at most 167 miles wide. Picture taken at the Life-giving Trinity Russian Orthodox Cathedral in Moscow, Russia on January 4, 2011.

  • The longest duration for a total solar eclipse is 7.5 minutes. Picture taken on January 04, 2011 in Locon, northern France.

  • Partial solar eclipses can be seen up to 3,000 miles from the "track" of totality. Picture taken in Baihata village, 30 kms from Guwahati, the capital city of the northeastern state of Assam in India on July 22, 2009.

  • The maximum number of solar eclipses (partial, annular, or total) is 5 per year, and there are at least 2 solar eclipses per year somewhere on the Earth. Picture taken in the Indian city of Varanasi on July 22, 2009.

  • Only partial solar eclipses can be observed from the North and South Poles. Picture taken over the statue of late Chinese leader Mao Zedong in Wuhan, Hubei province, China, on July 22, 2009.

  • Light filtering through leaves on trees casts crescent shadows as totality approaches. Picture taken on July 22, 2009 in Seoul, South Korea.

  • "Shadow bands" are often seen on the ground as the eclipse's peak approaches. Picture taken on January 04, 2011 in Rennes, western France.

  • During totality, the horizon is illuminated in a narrow band of light, because an observer is seeing distant localities not under the direct umbra, or area of darkness, of the Moon's shadow. Picture taken on January 4, 2011 in Old Damascus, Syria.

  • Local temperatures often drop 20 degrees or more near totality. Picture taken January 4, 2011 in Italy.

  • Every eclipse begins at sunrise at some point in its track and ends at sunset about half way around the world from the start point. Picture taken January 4, 2011 by the Hinode satellite.

  • Nearly identical eclipses (total, annual, or partial) occur after 18 years and 11 days, or every 6,585.32 days (Saros Cycle). Picture taken in Lahore, Pakistan on January 4, 2011.

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Filed by David Freeman  |