The dark center of the Moon’s shadow, the part where the Sun is completely blocked (the shadow’s umbra) is never more than about 160 miles wide by the time it reaches Earth, usually less. JMA/SSEC/University of Wisconsin at Madisonīut totality is reserved for a much smaller area. The islands of Indonesia are at lower left. Here's how the Moon's shadow looked as it crossed Earth during the total solar eclipse on March 9, 2016. The partial phases take their time the whole event usually runs about 3 hours from beginning to end. Then you may get a total solar eclipse, blacking out the Sun completely for anything from a few seconds up to 7½ minutes.Ī total eclipse also has partial-eclipse phases before and afterward. A deep partial eclipse, where the dent is big, turns the Sun into a dazzling crescent.īut the really good stuff happens if the Moon crosses the Sun nearly dead center as seen from your location. If the Moon crosses the Sun off center as seen from your location, you get only a partial solar eclipse, with the Moon’s silhouette making what looks like a dent in the Sun’s brilliant face. But about every six months on average, at least part of the new Moon crosses at least part of the Sun’s face as seen from somewhere on Earth. Usually the Moon misses the Sun in these monthly near-lineups (for reasons I’ll get to later). And we can’t see even that - because when the Moon is near our line of sight to the Sun, it’s hidden in the Sun’s dazzling glare in the bright blue daytime sky. This repeating journey brings the Moon close to our line of sight to the Sun at the time of “new Moon.” At that time the sunlit side of the Moon faces directly away from us the Moon shows us only its darkened night side. Celestial Geometryįirst off: The Moon orbits around Earth about once a month. One breakthrough was grasping the scene from another viewpoint: The Moon is a sunlit ball and casts a shadow, and we see an eclipse of the Sun when the Moon’ s shadow sweeps over us, like in the diagram above.īut there’s more to it than that - and if you want a fuller picture of what’s going to occur on April 8, 2024, read on. ![]() (Not to scale!)Įarth: Shutterstock / Fluidworkshop S&T Illustration: Patricia Gillis-Coppola In the penumbra the Moon covers only some of the Sun, for a partial eclipse. The shadow's umbra is the dark central part where the eclipse is total. When the Moon casts its shadow onto Earth, people on the ground see the Moon eclipsing the Sun.
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