What will the fate of Jupiter and its moons be during and after our sun becomes a red giant?
November 23, 2011 3:59 PM Subscribe
What will the fate of Jupiter and its moons be during and after our sun becomes a red giant? (or, please forward me to reliable sources with information beyond a first-order Google search)
For context, I've been working on a D&D campaign world with realistic physics and I would like to set a campaign on Europa or one of Jupiter's other large moons, post the transition of our sun to its red giant state. In addition to needing to calculate what astronomy (the patterns of the sun, Jupiter, and other moons in the sky) would look like, I first need to work out reasonable adjusted orbits given the mainsequence -> red giant transition.
Here's what I've put together so far, please help me by adding to it (or suggesting references specifically about Jupiter and/or its moons) or correcting my preliminary ideas below. Thanks! :)
The first major event in Jupiter's timeline will be when the sun becomes a red giant. As the sun expands, it will lose mass, and all of the planetary orbits will increase in distance from the sun and in orbital length. The habitable zone (where liquid water exists) will also move much further out.
Most references I've found seem to imply that the inner planets are goners, but that the gas giants won't be affected too much. Would they be stripped of gas by the solar winds? Would the water on Europa melt but then quickly evaporate away completely? I'm skeptical Jupiter would move as far out as the inner edge of the new habitable zone... yet most online references don't indicate that the gas giants would be stripped of their gasses.
Also, would the moons likely keep their orbits thorough all of this, or would Jupiter moving throw everything off?
In short, what would the experience be like from the perspective of Jupiter, or, if it's possible to know, from the perspective of Jupiter's moon Europa.
Thanks!
For context, I've been working on a D&D campaign world with realistic physics and I would like to set a campaign on Europa or one of Jupiter's other large moons, post the transition of our sun to its red giant state. In addition to needing to calculate what astronomy (the patterns of the sun, Jupiter, and other moons in the sky) would look like, I first need to work out reasonable adjusted orbits given the mainsequence -> red giant transition.
Here's what I've put together so far, please help me by adding to it (or suggesting references specifically about Jupiter and/or its moons) or correcting my preliminary ideas below. Thanks! :)
The first major event in Jupiter's timeline will be when the sun becomes a red giant. As the sun expands, it will lose mass, and all of the planetary orbits will increase in distance from the sun and in orbital length. The habitable zone (where liquid water exists) will also move much further out.
Most references I've found seem to imply that the inner planets are goners, but that the gas giants won't be affected too much. Would they be stripped of gas by the solar winds? Would the water on Europa melt but then quickly evaporate away completely? I'm skeptical Jupiter would move as far out as the inner edge of the new habitable zone... yet most online references don't indicate that the gas giants would be stripped of their gasses.
Also, would the moons likely keep their orbits thorough all of this, or would Jupiter moving throw everything off?
In short, what would the experience be like from the perspective of Jupiter, or, if it's possible to know, from the perspective of Jupiter's moon Europa.
Thanks!
The Sun will actually lose mass, because it will be blowing off its outer layers by a strong solar wind. Compared to that mass loss, the terrestrial planets are peanuts.
It's not something that has been modeled conclusively, as far as I know—they're still debating, for example, whether Earth will actually be engulfed or not.
If I had to guess, I'd say the solar wind wouldn't be enough to strip away a lot of gas from Jupiter. Jupiter's magnetic field will protect it from the worst of it.
However, the Sun at its peak brightness will be something 1,000 - 10,000 times as bright as it is now, and Jupiter is only 5 times farther than the Earth, so I'd rather be around Neptune, where the Sun, at its brightest, will be only 1-10 times brighter than it is now from Earth—but then Neptune's magnetic field isn't as strong as Jupiter's, and the solar wind might be a greater concern.
posted by BrashTech at 4:14 PM on November 23, 2011
It's not something that has been modeled conclusively, as far as I know—they're still debating, for example, whether Earth will actually be engulfed or not.
If I had to guess, I'd say the solar wind wouldn't be enough to strip away a lot of gas from Jupiter. Jupiter's magnetic field will protect it from the worst of it.
However, the Sun at its peak brightness will be something 1,000 - 10,000 times as bright as it is now, and Jupiter is only 5 times farther than the Earth, so I'd rather be around Neptune, where the Sun, at its brightest, will be only 1-10 times brighter than it is now from Earth—but then Neptune's magnetic field isn't as strong as Jupiter's, and the solar wind might be a greater concern.
posted by BrashTech at 4:14 PM on November 23, 2011
It will take 4 to five billion years before the sun enters a red giant phase (which it may or may not due because of it's smallish mass).
Long before that , about a billion years before, the Andromeda Galaxy will first collide with the Milky way. The gravitational effects from such an merger will probably severely disrupt our Oort cloud (along with the rest of the suns in the galaxy) at the very least. This means big things at the very edges of the solar system will enter the system and all the planets orbits will be severely disrupted. Jupiter and a lot of the current planets will be lucky to not be ejected from the system entirely. Likely none of the existing planets will remain in their current orbits.
posted by Poet_Lariat at 4:20 PM on November 23, 2011 [3 favorites]
Long before that , about a billion years before, the Andromeda Galaxy will first collide with the Milky way. The gravitational effects from such an merger will probably severely disrupt our Oort cloud (along with the rest of the suns in the galaxy) at the very least. This means big things at the very edges of the solar system will enter the system and all the planets orbits will be severely disrupted. Jupiter and a lot of the current planets will be lucky to not be ejected from the system entirely. Likely none of the existing planets will remain in their current orbits.
posted by Poet_Lariat at 4:20 PM on November 23, 2011 [3 favorites]
Do you have a citation for that, Poet_Lariat?
The Milky Way has no doubt undergone mergers with galaxies in the past (albeit probably not as large as Andromeda) and stars still have planets.
posted by BrashTech at 5:14 PM on November 23, 2011 [1 favorite]
The Milky Way has no doubt undergone mergers with galaxies in the past (albeit probably not as large as Andromeda) and stars still have planets.
posted by BrashTech at 5:14 PM on November 23, 2011 [1 favorite]
BrashTech: I did not say that no stars would have planets. I did say that the merger of our Galaxy with a much larger galaxy (one trillion suns) is going to completely disrupt the structures of both galaxies (google for merger simulations and watch). It is not unreasonable to think that a large number of planetary systems as well as their Oort clouds will be severely disrupted.
Also, our galaxy has only merged with dwarf galaxies in the past. There is no historical or galactic structural evidence in our galaxy to believe that it has ever merged with anything remotely equal in size (at least since the spiral structure has firmed) to the Andromeda galaxy.
posted by Poet_Lariat at 7:32 PM on November 23, 2011
Also, our galaxy has only merged with dwarf galaxies in the past. There is no historical or galactic structural evidence in our galaxy to believe that it has ever merged with anything remotely equal in size (at least since the spiral structure has firmed) to the Andromeda galaxy.
posted by Poet_Lariat at 7:32 PM on November 23, 2011
Best answer: While Poet_Lariat may be correct, it is a definite maybe: the distance between stars is vast, even in merging galaxies. Three-body problems are hard enough to work out: it's not clear what interactions, if any, might happen on a planetary scale due to galactic interactions... and it's going too far, in my opinion, to predict any Velikovsky-style re-ordering of our solar system.
More to the point, there have been some conjectures that the Sun expanding to a red giant will make the moons of Jupiter and Saturn habitable. Essentially, the planets are thought not to move in, but the Sun's heliosphere will move out, to approximately where the earth is now, and grow hotter. Any moon suspected to be rich in water - Enceladus, Titan, Europa, etc - may become habitable, at least in human terms. (Enceladus isn't dense enough to hold on to an atmosphere, but Titan and Europa might). Methane on the moons, currently frozen or in a liquid state, would heat into a gas, possibly contributing to a greenhouse effect. Nothing I've read suggests that the solar wind - currently an important but very tenuous force - would blow off the atmospheres of the outer planets. The inverse square law still applies, and the gas giants are a long ways from the sun, even as a bloated red giant.
All of this would happen very slowly, over hundreds of millions of years, so there's little possibility of the moons being thrown out of their orbits. The best fictional treatment of those changes, seven billion years hence, at least that I'm aware of, is Stephen Baxter's Titan, and I think that the last few chapters of that book may be your best resource for the purpose of world-building in your game.
posted by Bora Horza Gobuchul at 9:03 PM on November 23, 2011
More to the point, there have been some conjectures that the Sun expanding to a red giant will make the moons of Jupiter and Saturn habitable. Essentially, the planets are thought not to move in, but the Sun's heliosphere will move out, to approximately where the earth is now, and grow hotter. Any moon suspected to be rich in water - Enceladus, Titan, Europa, etc - may become habitable, at least in human terms. (Enceladus isn't dense enough to hold on to an atmosphere, but Titan and Europa might). Methane on the moons, currently frozen or in a liquid state, would heat into a gas, possibly contributing to a greenhouse effect. Nothing I've read suggests that the solar wind - currently an important but very tenuous force - would blow off the atmospheres of the outer planets. The inverse square law still applies, and the gas giants are a long ways from the sun, even as a bloated red giant.
All of this would happen very slowly, over hundreds of millions of years, so there's little possibility of the moons being thrown out of their orbits. The best fictional treatment of those changes, seven billion years hence, at least that I'm aware of, is Stephen Baxter's Titan, and I think that the last few chapters of that book may be your best resource for the purpose of world-building in your game.
posted by Bora Horza Gobuchul at 9:03 PM on November 23, 2011
I believe I've read suppositions where the outer gas giants will, essentially, have their atmospheres burned-away by the expanding Sun.
posted by Thorzdad at 5:55 AM on November 24, 2011
posted by Thorzdad at 5:55 AM on November 24, 2011
Response by poster: Thanks everyone! I think I'm getting the big picture: we don't yet really understand what may happen on these time scales. But thanks for the tips, it's good to have an idea of the range of current predictions.
So I think I'm going to be using Europa as a model after all, jumping forward the billions of years necessary for many of the gas giant moons to be covered in liquid water. In case you were curious, the premise for the epic-level plot of the run is that "thousands of years ago, a benevolent-explorer race (think star trek) gets caught up in an intergalactic war. They protect Lly (my game world) by hiding its water in a magically shielded plane inside the planet. At the time, Lly was a world with relatively young intelligent life, but was at risk because the enemy had begun to target "supply" worlds with enormous, magical, water-seeking missiles. But this explorer race miscalculates in that Lly is a "sentient world" and reacts "poorly" to having all of its water drained. As a result, thousands of years later, life has recovered, but must still cope with the acute shortage of water. Though, eventually, maybe my players will restore water to the world." :)
Thanks Again!
posted by ch3cooh at 10:13 PM on November 24, 2011
So I think I'm going to be using Europa as a model after all, jumping forward the billions of years necessary for many of the gas giant moons to be covered in liquid water. In case you were curious, the premise for the epic-level plot of the run is that "thousands of years ago, a benevolent-explorer race (think star trek) gets caught up in an intergalactic war. They protect Lly (my game world) by hiding its water in a magically shielded plane inside the planet. At the time, Lly was a world with relatively young intelligent life, but was at risk because the enemy had begun to target "supply" worlds with enormous, magical, water-seeking missiles. But this explorer race miscalculates in that Lly is a "sentient world" and reacts "poorly" to having all of its water drained. As a result, thousands of years later, life has recovered, but must still cope with the acute shortage of water. Though, eventually, maybe my players will restore water to the world." :)
Thanks Again!
posted by ch3cooh at 10:13 PM on November 24, 2011
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posted by dfriedman at 4:02 PM on November 23, 2011 [1 favorite]