<http://schema.org/alternativeHeadline>
"Predicting a solar eclipse requires an understanding of the motions of the sun and the moon as well as accurate calculations about the distance to the moon."^^<http://www.w3.org/2001/XMLSchema#string>
<http://www.mnn.com/earth-matters/space/stories/how-often-do-total-solar-eclipses-occur-and-why>