Abstract
We all live in a gravitational “hole”, produced by the earth’s gravitational field. By human (but not cosmic) standards, it takes quite a bit of energy to climb out of our hole before we can travel freely in space to other planets or stars. Light, however, has no trouble escaping the earth, so from a distance our planet appears as a pale blue object in reflected sunlight, not black at all.
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© 2012 Springer-Verlag Berlin Heidelberg
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Meier, D.L. (2012). Recognizing Black Holes. In: Black Hole Astrophysics. Springer Praxis Books(). Springer, Berlin, Heidelberg. https://doi.org/10.1007/978-3-642-01936-4_1
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DOI: https://doi.org/10.1007/978-3-642-01936-4_1
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Publisher Name: Springer, Berlin, Heidelberg
Print ISBN: 978-3-642-01935-7
Online ISBN: 978-3-642-01936-4
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