CAROLYN CINAMI DECRISTOFANO is the author of "Leonardo's ABCs (Museum of Science, Boston). She has developed science programs with NASA and the Harvard-Smithsonian Center for Astrophysics. Carolyn lives in Plympton, Massachusetts.
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If a black hole is not a hole, then what is it? Find out what black holes are, what causes them, and how scientists first discovered them. Learn how astronomers find black holes, get to know our nearest black-hole neighbor, and take a journey that will li... SEE MORE