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Question

Since the sun is one giant ball of gas, what force holds its consistent shape and size? Why doesn't it expand and burn up quickly?
Asked by: J.J. True

Answer

The Sun maintains its size and shape against the outward pressure of fusion energy by the force of gravity. In other words, its own weight keeps the Sun from growing larger.

It is the stable balance of outward gas pressure vs. the inward pull of gravity that determines the size of any star.

The predominantly spherical shape of all but the smallest astronomical bodies (asteroids, for example) is due to the radially symmetric nature of the gravitational force.
Answered by: Paul Walorski, B.A. Physics, Part-time Physics Instructor


Science Quote

'An expert is someone who knows some of the worst mistakes that can be made in his subject and how to avoid them.'

Werner Heisenberg
(1901-1976)


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