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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

'There is no inductive method which could lead to the fundamental concepts of physics. Failure to understand this fact constituted the basic philosophical error of so many investigators of the nineteenth century.'

Albert Einstein
(1879-1955)


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