Why planets do not collapse under its own gravity unlike stars?

It is well known that stars do not collapse under its own gravity as long as there is nuclear fusion reaction which counteracts/balances gravity. But in contrast planets do not have any reaction that could balance its mass. So how and what is preventing planetary mass from collapsing by itself (I am not saying planets should collapse and form a black hole which does not happen as long as the mass is less than 1.4 times solar mass, but still there must be collapse in the absence of any counter active force)?

6 Answers

  • Feythe
    Lv 5
    1 decade ago
    Best Answer

    "Electron Degeneracy Pressure" will halt the gravitational collapse of a star if its mass is below the Chandrasekhar Limit (1.38 solar masses). This is the pressure that prevents a white dwarf star from collapsing.

    Anything with less than 1.38 solar masses (1 solar mass is the size of our sun) will be too small to collapse under its own gravity.

    Most planets are far smaller than that. :-)

  • 1 decade ago

    The reason why planets and low mass starts do not collapse to form black holes has to do with the electrons orbiting the atoms. As gravity causes matter to get closer together, the repelling force of the electrons increase, and that stops further collapse. For stars more than 1.4 solar masses but less than three, electrons cannot hold up the star from collapsing, but then the neutrons get dripped out of the nuclei, exerting a new force that holds up the star from collapsing. If the mass exceeds three solar masses, then even that won't work, and the star collapse into a black hole.

  • Tom S
    Lv 7
    1 decade ago

    Nuclear forces resist the collapse, in stars there is so much gravity that this is not enough to stop collapse. The mass of planets is not great enough to create this much gravity.

  • Anonymous
    1 decade ago

    For a planet like the Earth, the structural strength of the rock holds it up, so basically chemical forces. For gas giants like Jupiter, they actually *are* gravitationally collapsed. It is electron degeneracy deep inside the planet that prevents it from becoming a black hole: the same force that holds up white dwarf stars.

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  • 1 decade ago

    why dosn't a building fall to the ground and cruble??? its the structure a star is a hot molten thing so thats what

  • Anonymous
    1 decade ago

    uh huh ! ?

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