Sometimes it is hard to imagine why eclipses happen. Try this experiment and see if it helps you to understand.
Look at the Earth. What do you see?You should see a shadow that is darker in the middle and lighter on the outside. The darker part of the shadow represents the umbra, the shadow of the Moon in which total solar eclipses can be seen.The lighter part of the shadow represents the penumbra, from which only partial solar eclipses are seen.
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StarChild Graphics & Music: Acknowledgments
StarChild Project Leader: Dr. Laura A. Whitlock
Responsible NASA Official: Phil Newman