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Let's say the rogue planet is a massive, super-cold planet. How big and how cold would it have to be to lower the Sun's energy output just enough to trigger a "

Let's say the rogue planet is a massive, super-cold planet. How big and how cold would it have to be to lower the Sun's energy output just enough to trigger a "Snowball Earth" scenario? Assume a direct hit.

ben_w 8y ago
The extra mass of the planet would increase the rate of fusion. https://what-if.xkcd.com/14/ https://what-if.xkcd.com/14/
- cobbzilla 8y ago
  to a point you are right, but clearly there is some boundary, right? imagine a solid object with a mass just below the Chandrasekhar limit and a temperature near absolute zero. Don't tell me hurtling that into the Sun will make it burn hotter. And even if it would (or a smaller object) in the long run, there would at least be some period of time before the incoming matter reached fusionable temperatures, reducing power output in the short term.
  - sudhirj 8y ago
    Seems unlikely for fusion. Think of it from the point of view of star formation - the gas that coalesces into a ball is already super cold from floating around in space. The heat for fusion comes from gravity compressing the matter, not from the starting heat energy present in the matter itself. So yeah, you can't really add cold stuff to starts to extinguish them - stars are made from absolute ice to being with.
    - cobbzilla 8y ago
      wow. i had never thought of it like that. thank you.
      - dc443 8y ago
        ya, the steady-state temp of a star is a byproduct of its fusion process, which is directly controlled by the pressure of gravity. More mass, more gravity... the kinetic energy of the temperature of that mass pales in comparison to the E=mc^2 energy contained in that mass.
  - ben_w 8y ago
    I think you just described what happens to a stellar core during a supernova. The temperature difference between the surface and core of a red giant is so large the surface might as well be “near absolute zero”.
ChuckMcM 8y ago
I think the only way this works is if the planet doesn't hit the Sun. One could imagine a scenario (but the orbital mechanics don't work out) where a massive rogue planet enters into the solar system and interposes itself between the Earth and Sun, thus shading the Earth and dropping its temperature the required amount. Sort of like a month long solar eclipse or something. But at that mass it's probably pulling Earth out of its orbit so that scenario is not really very plausible. If it hits the Sun, it really doesn't matter how cold or how massive it is (up until it becomes a brown dwarf at which point we're talking binary star interaction levels of mass). The thing is that the Sun is really spectacularly huge. You could fit over a million earth size planets inside of it. And it is a run away fusion reactor so it is kind of like throwing frozen beer cans into a 500 acre California wildfire. Very little effect on the fire (although any embedded Hot Shot firefighters will appreciate your effort). But things are even easier than actually hitting the Sun in this case. If you're trying to just screw up the Earth, any rogue planet that flew through the Solar system and pulled earth more than about 6 - 8% off its existing orbit should completely wreck the climate. If you were a fiction writer you'd want it to be bad enough that people could survive long enough to write a story about it or course. Generally though any astronomical mass that would nominally qualify as a planet flying within a million miles of the Earth is going to likely trigger an extinction level event. Especially if it is off the ecliptic by some amount.
- restalis 8y ago
  "where a massive rogue planet enters into the solar system and interposes itself between the Earth and Sun, thus shading the Earth and dropping its temperature the required amount. Sort of like a month long solar eclipse" For our planet's distance from the sun, I have a hard time imagining how anything without self propulsion could maintain a stable orbital position to cast a shade over us for a long enough period (e.g. a month).

ben_w 8y ago

The extra mass of the planet would increase the rate of fusion. https://what-if.xkcd.com/14/ https://what-if.xkcd.com/14/

cobbzilla 8y ago
to a point you are right, but clearly there is some boundary, right? imagine a solid object with a mass just below the Chandrasekhar limit and a temperature near absolute zero. Don't tell me hurtling that into the Sun will make it burn hotter. And even if it would (or a smaller object) in the long run, there would at least be some period of time before the incoming matter reached fusionable temperatures, reducing power output in the short term.
- sudhirj 8y ago
  Seems unlikely for fusion. Think of it from the point of view of star formation - the gas that coalesces into a ball is already super cold from floating around in space. The heat for fusion comes from gravity compressing the matter, not from the starting heat energy present in the matter itself. So yeah, you can't really add cold stuff to starts to extinguish them - stars are made from absolute ice to being with.
  - cobbzilla 8y ago
    wow. i had never thought of it like that. thank you.
    - dc443 8y ago
      ya, the steady-state temp of a star is a byproduct of its fusion process, which is directly controlled by the pressure of gravity. More mass, more gravity... the kinetic energy of the temperature of that mass pales in comparison to the E=mc^2 energy contained in that mass.
- ben_w 8y ago
  I think you just described what happens to a stellar core during a supernova. The temperature difference between the surface and core of a red giant is so large the surface might as well be “near absolute zero”.

ChuckMcM 8y ago

I think the only way this works is if the planet doesn't hit the Sun. One could imagine a scenario (but the orbital mechanics don't work out) where a massive rogue planet enters into the solar system and interposes itself between the Earth and Sun, thus shading the Earth and dropping its temperature the required amount. Sort of like a month long solar eclipse or something. But at that mass it's probably pulling Earth out of its orbit so that scenario is not really very plausible. If it hits the Sun, it really doesn't matter how cold or how massive it is (up until it becomes a brown dwarf at which point we're talking binary star interaction levels of mass). The thing is that the Sun is really spectacularly huge. You could fit over a million earth size planets inside of it. And it is a run away fusion reactor so it is kind of like throwing frozen beer cans into a 500 acre California wildfire. Very little effect on the fire (although any embedded Hot Shot firefighters will appreciate your effort). But things are even easier than actually hitting the Sun in this case. If you're trying to just screw up the Earth, any rogue planet that flew through the Solar system and pulled earth more than about 6 - 8% off its existing orbit should completely wreck the climate. If you were a fiction writer you'd want it to be bad enough that people could survive long enough to write a story about it or course. Generally though any astronomical mass that would nominally qualify as a planet flying within a million miles of the Earth is going to likely trigger an extinction level event. Especially if it is off the ecliptic by some amount.

restalis 8y ago
"where a massive rogue planet enters into the solar system and interposes itself between the Earth and Sun, thus shading the Earth and dropping its temperature the required amount. Sort of like a month long solar eclipse" For our planet's distance from the sun, I have a hard time imagining how anything without self propulsion could maintain a stable orbital position to cast a shade over us for a long enough period (e.g. a month).