What is hydrogen fusion in solar-like stars, and why…

What is hydrogen fusion in solar-like stars, and why…

What is hydrogen fusion in solar-like stars, and why is it fundamentally different from the burning
of a log in a re place on Earth?
(b) Why do thermonuclear reactions occur only in the core of
the stars, and not in the outer parts, nor in bottles of hydrogen gas on Earth? 

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