38:21
Core astronomy
Core Astronomy examines the key points in the development of astronomy, beginning with Greek astronomer Ptolemy's Earth-centered paradigm to Nicolas Copernicus' introduction of a sun-centered solar system, and Isaac Newton's three laws of motion. It...
52:09
Who's Afraid of a Big Black Hole?
Black holes are by definition invisible, and there is no scientific theory that can adequately explain them. Nevertheless, researchers are determined to unravel the mysteries of black holes in the hope of answering some of the universe’s most pres...