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Eventually, but it would take much, much longer than you'd think. Jupiter, Saturn and Neptune all radiate ~2x the heat they receive from the Sun. Most of their

Eventually, but it would take much, much longer than you'd think. Jupiter, Saturn and Neptune all radiate ~2x the heat they receive from the Sun. Most of their heat is primordial, residue from the gravitational potential energy of all their component parts falling together. A gas giant flung away from it's host star will likely remain more or less as it is much longer than the star is.

actually_a_dog 5y ago
Just to add on to this, NASA estimates that the internal core temperature of Jupiter could be as hot as 24,000°K [0]. For reference, the Sun's photosphere has a temperature of about 6000°K [1]. --- [0]: https://www.nasa.gov/audience/forstudents/5-8/features/nasa-knows/what-is-jupiter-58.html https://www.nasa.gov/audience/forstudents/5-8/features/nasa-... [1]: https://www.scientificamerican.com/article/i-read-that-the-suns-surf/ https://www.scientificamerican.com/article/i-read-that-the-s...
- hollerith 5y ago
  For reference the temperature at the center of the sun is about 15 million °K
- perl4ever 5y ago
  >the Sun's photosphere has a temperature of about 6000° There was a paper that proposed that Earth's surface was about this hot for a while after the collision that formed the Moon. Even though the heat wasn't coming from nuclear fusion, for a while it was just as hot as a star, so the Moon, which was smaller and cooled faster overall, was remelted in places by "Earthshine" - therefore the discrepancy between the maria on the near side and the far side.
areoform 5y ago
> Jupiter, Saturn and Neptune all radiate ~2x the heat they receive from the Sun. As I've said elsewhere, this is most surprising for Neptune, but the fact that these bodies radiate this much heat is a clue that something more is going on. The primordial heat hypothesis doesn't hold up, as Uranus was formed around the same time as Neptune and its energy balance is 1.05. If the comparison is indeed accurate, then the question remains what is making these planetary bodies so hot? Neptune especially. Here are the energy balances of each to our best estimates, Jupiter, 2.132 ± 0.051 [current estimate, older estimate was, 1.668 ± 0.085] (source, https://www.nature.com/articles/s41467-018-06107-2#Sec2 https://www.nature.com/articles/s41467-018-06107-2#Sec2) Saturn, 1.78 ± 0.09 (source, https://www.sciencedirect.com/science/article/abs/pii/0019103583901471 https://www.sciencedirect.com/science/article/abs/pii/001910... ) Neptune 2.61 ± 0.28 (source, https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/91JA01087 https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/91JA... ) My tweets on the topic, https://twitter.com/_areoform/status/1373376028861734918 https://twitter.com/_areoform/status/1373376028861734918
- Tuna-Fish 5y ago
  > as Uranus was formed around the same time as Neptune [citation needed] There is clearly an unexplained anomaly vis-a-vis Uranus and the other giant planets. But the closer you look at them, the more weird Uranus appears. It would be amazing if it turned out to be a much older planet captured by our solar system. (That would certainly explain the weirdo rotation...)
  - areoform 5y ago
    Here you go! https://books.google.com/books?id=RaJdy3_VINQC&pg=PA224&lpg=PA224&dq=planet+neptune+heat+flow&redir_esc=y#v=onepage&q=planet%20neptune%20heat%20flow&f=false https://books.google.com/books?id=RaJdy3_VINQC&pg=PA224&lpg=... https://iopscience.iop.org/article/10.1088/0004-637X/789/1/69 https://iopscience.iop.org/article/10.1088/0004-637X/789/1/6... http://www.psrd.hawaii.edu/Aug01/bombardment.html http://www.psrd.hawaii.edu/Aug01/bombardment.html For me the anomaly is the heat of these planets, and the physical processes this suggests. I suspect that our current explanations are only partial and that a great discovery lies somewhere here.
  - actually_a_dog 5y ago
    Uranus got knocked over by getting hit really hard, a bunch of times: https://www.space.com/13231-planet-uranus-knocked-sideways-impacts.html https://www.space.com/13231-planet-uranus-knocked-sideways-i...
- TheSpiceIsLife 5y ago
  Do we know if any exoplanet gas giants are similar in this regard? If an observer from a distant star, say any of the stars we've discovered planets around, were observing our solar system, would the gas giants stand out because of this, or are they still too close as to be out-shone by Sol?

actually_a_dog 5y ago

Just to add on to this, NASA estimates that the internal core temperature of Jupiter could be as hot as 24,000°K [0]. For reference, the Sun's photosphere has a temperature of about 6000°K [1]. --- [0]: https://www.nasa.gov/audience/forstudents/5-8/features/nasa-knows/what-is-jupiter-58.html https://www.nasa.gov/audience/forstudents/5-8/features/nasa-... [1]: https://www.scientificamerican.com/article/i-read-that-the-suns-surf/ https://www.scientificamerican.com/article/i-read-that-the-s...

hollerith 5y ago
For reference the temperature at the center of the sun is about 15 million °K
perl4ever 5y ago
>the Sun's photosphere has a temperature of about 6000° There was a paper that proposed that Earth's surface was about this hot for a while after the collision that formed the Moon. Even though the heat wasn't coming from nuclear fusion, for a while it was just as hot as a star, so the Moon, which was smaller and cooled faster overall, was remelted in places by "Earthshine" - therefore the discrepancy between the maria on the near side and the far side.

areoform 5y ago

> Jupiter, Saturn and Neptune all radiate ~2x the heat they receive from the Sun. As I've said elsewhere, this is most surprising for Neptune, but the fact that these bodies radiate this much heat is a clue that something more is going on. The primordial heat hypothesis doesn't hold up, as Uranus was formed around the same time as Neptune and its energy balance is 1.05. If the comparison is indeed accurate, then the question remains what is making these planetary bodies so hot? Neptune especially. Here are the energy balances of each to our best estimates, Jupiter, 2.132 ± 0.051 [current estimate, older estimate was, 1.668 ± 0.085] (source, https://www.nature.com/articles/s41467-018-06107-2#Sec2 https://www.nature.com/articles/s41467-018-06107-2#Sec2) Saturn, 1.78 ± 0.09 (source, https://www.sciencedirect.com/science/article/abs/pii/0019103583901471 https://www.sciencedirect.com/science/article/abs/pii/001910... ) Neptune 2.61 ± 0.28 (source, https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/91JA01087 https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/91JA... ) My tweets on the topic, https://twitter.com/_areoform/status/1373376028861734918 https://twitter.com/_areoform/status/1373376028861734918

Tuna-Fish 5y ago
> as Uranus was formed around the same time as Neptune [citation needed] There is clearly an unexplained anomaly vis-a-vis Uranus and the other giant planets. But the closer you look at them, the more weird Uranus appears. It would be amazing if it turned out to be a much older planet captured by our solar system. (That would certainly explain the weirdo rotation...)
- areoform 5y ago
  Here you go! https://books.google.com/books?id=RaJdy3_VINQC&pg=PA224&lpg=PA224&dq=planet+neptune+heat+flow&redir_esc=y#v=onepage&q=planet%20neptune%20heat%20flow&f=false https://books.google.com/books?id=RaJdy3_VINQC&pg=PA224&lpg=... https://iopscience.iop.org/article/10.1088/0004-637X/789/1/69 https://iopscience.iop.org/article/10.1088/0004-637X/789/1/6... http://www.psrd.hawaii.edu/Aug01/bombardment.html http://www.psrd.hawaii.edu/Aug01/bombardment.html For me the anomaly is the heat of these planets, and the physical processes this suggests. I suspect that our current explanations are only partial and that a great discovery lies somewhere here.
- actually_a_dog 5y ago
  Uranus got knocked over by getting hit really hard, a bunch of times: https://www.space.com/13231-planet-uranus-knocked-sideways-impacts.html https://www.space.com/13231-planet-uranus-knocked-sideways-i...
TheSpiceIsLife 5y ago
Do we know if any exoplanet gas giants are similar in this regard? If an observer from a distant star, say any of the stars we've discovered planets around, were observing our solar system, would the gas giants stand out because of this, or are they still too close as to be out-shone by Sol?