What:

"Like the sun, they begin life as cloud of gas that collapses and heats up until the hydrogen in its core "catches fire" and starts fusing into helium, like a gigantic H-bomb held together by its own gravity. The core is surrounded by a envelope of cooler gas that transmits energy to the surface by convection and radiation, but doesn't actually do any fusion itself."

Writer: John Baez

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Date: Apr 27 2016 6:53 PM