What will be the fate of the outer planets and dwarf planets

[Grimlock]

When the sun burns out its fuel in around 5 billion years or so, what will be the fate of all the outer planets will they continue to orbit in the current orbit or will they "go of on a little journey through space until we say hello with the neighbor galaxy.

Also lets say mankind is still around when that happens not on earth but on a different planet, will we even notice the two galaxies smashing together or will the best we can hope for be a little fireworks in the sky?

 

[AdmiralPeacock]

Re: What will be the fate of the outer planets and dwarf pla

When the sun burns out its fuel in around 5 billion years or so, what will be the fate of all the outer planets will they continue to orbit in the current orbit or will they "go of on a little journey through space until we say hello with the neighbor galaxy.

Also lets say mankind is still around when that happens not on earth but on a different planet, will we even notice the two galaxies smashing together or will the best we can hope for be a little fireworks in the sky?

1 probably change orbit or fly off into interstellar space.

2 We would barely notice (if the Earth was still around) even if system was flung into intergalactic space - the sky will merely fill with more stars (or less). Now if the two super massive blackholes collide, that would be "fun"

 

[Womble]

Re: What will be the fate of the outer planets and dwarf pla

There's speculation that Titan might see the development of life when that happens. It should recieve more light and energy from the sun and it's presently thought to be a good match for conditions on the early earth when life formed.

 

[duclicsic]

Re: What will be the fate of the outer planets and dwarf pla

When the sun finally burns through each increasingly difficult to fuse fuel store, it will shed quantities of mass into interstellar space to create a planetary nebula. With a lower central mass to orbit the outer planets would recede I guess, I don't know how much force the advancing nebulous cloud would impart on them though. Who knows, bodies like Jupiter may be able to accrue enough new mass from the nebula to finally light up themselves.
As for the galaxy collision, it's not like it would be some event you could watch. An entire human lifetime would pass by in the middle of the 'collision' and there would be no noticeable change to the relative positions of the interacting galaxies. These events take hundreds of millions if not billions of years to play out, you would notice it just about as well as you notice the rotation of the milky way. The only kind of resultant event that would be significant and observable on the timescale of a human life would be a close pass with a star or similar massive object in said galaxy. We would be able to predict it well in advance of course, but if it were close enough to mess with the orbits in our solar system the changes could be quite dramatic.

 

[sgrunterundt]

Re: What will be the fate of the outer planets and dwarf pla

When the sun burns out its fuel in around 5 billion years or so, what will be the fate of all the outer planets will they continue to orbit in the current orbit or will they "go of on a little journey through space until we say hello with the neighbor galaxy.

Also lets say mankind is still around when that happens not on earth but on a different planet, will we even notice the two galaxies smashing together or will the best we can hope for be a little fireworks in the sky?

Outer planets will not change orbit much. They will get warmer for a while and then continue to orbit the white dwarf.

Why would we be on a planet at all at that time? Hopefully in as little as a few hundred years planets will have only historic importance. Space habitats are much more efficient in the long run.

New star formation induced by the galaxy collision will probably make for a somewhat more interesting sky. But not incredibly spectacular. The band of the Milky Way is pretty hard to make out unless you have very good viewing conditions.

 

[RigelKentaurusA]

Re: What will be the fate of the outer planets and dwarf pla

Any change in the orbits of the outer planets will be driven by the solar mass loss. Everything orbiting the sun will drift outward some. The outer solar system planets are probably stable for the rest of the sun's existence (even into the white dwarf phase).

 

[Anachronous Rex]

Re: What will be the fate of the outer planets and dwarf pla

My understanding was that the Jovian moons are comprised of a lot more water than the rocky objects of the inter solar system.

This is pure speculation on my part, but might not an expanding sun prove very damaging to such bodies?

 

[RigelKentaurusA]

Re: What will be the fate of the outer planets and dwarf pla

My understanding was that the Jovian moons are comprised of a lot more water than the rocky objects of the inter solar system.

This is true.

This is pure speculation on my part, but might not an expanding sun prove very damaging to such bodies?

Taking HD 47536 (K1III star, 0.94 solar mass, 181 times solar luminosity, 23.5 solar radii) as an example of what the sun will become, Jupiter will receive 6.692 times the amount of energy from the sun that Earth currently does now. This amount of insolation is comparable to what Mercury gets now (6.818 x Earth). So, yes. Jupiter's icy moons will be evaporated to the core.

Saturn will have an insolation of 1.993 times what Earth gets now. Probably enough to evaporate much of the mass of it's moons. Uranus will get 0.492 times the amount of insolation Earth currently does, comparable to what Mars gets now (0.433). Neptune will get 0.21 times as much energy from the sun as Earth gets now.

 

[Anachronous Rex]

Re: What will be the fate of the outer planets and dwarf pla

My understanding was that the Jovian moons are comprised of a lot more water than the rocky objects of the inter solar system.

This is true.

This is pure speculation on my part, but might not an expanding sun prove very damaging to such bodies?

Taking HD 47536 (K1III star, 0.94 solar mass, 181 times solar luminosity, 23.5 solar radii) as an example of what the sun will become, Jupiter will receive 6.692 times the amount of energy from the sun that Earth currently does now. This amount of insolation is comparable to what Mercury gets now (6.818 x Earth). So, yes. Jupiter's icy moons will be evaporated to the core.

Saturn will have an insolation of 1.993 times what Earth gets now. Probably enough to evaporate much of the mass of it's moons. Uranus will get 0.492 times the amount of insolation Earth currently does, comparable to what Mars gets now (0.433). Neptune will get 0.21 times as much energy from the sun as Earth gets now.

Thanks mate, very informative.

 

[Pulsar]

Re: What will be the fate of the outer planets and dwarf pla

Taking HD 47536 (K1III star, 0.94 solar mass, 181 times solar luminosity, 23.5 solar radii) as an example of what the sun will become, Jupiter will receive 6.692 times the amount of energy from the sun that Earth currently does now. This amount of insolation is comparable to what Mercury gets now (6.818 x Earth). So, yes. Jupiter's icy moons will be evaporated to the core.

Saturn will have an insolation of 1.993 times what Earth gets now. Probably enough to evaporate much of the mass of it's moons. Uranus will get 0.492 times the amount of insolation Earth currently does, comparable to what Mars gets now (0.433). Neptune will get 0.21 times as much energy from the sun as Earth gets now.

I wonder what the effect of wavelength is. A red giant will emit most of its light in the red wavelength band. I don't know what influence that would have on evaporation.

 

[RigelKentaurusA]

Re: What will be the fate of the outer planets and dwarf pla

Those calculations were done for the sum of the energy from the star (across all wavelengths). I'm not sure if it would make a significant difference about the redder bias.

 

[sgrunterundt]

Re: What will be the fate of the outer planets and dwarf pla

Taking HD 47536 (K1III star, 0.94 solar mass, 181 times solar luminosity, 23.5 solar radii) as an example of what the sun will become, Jupiter will receive 6.692 times the amount of energy from the sun that Earth currently does now. This amount of insolation is comparable to what Mercury gets now (6.818 x Earth). So, yes. Jupiter's icy moons will be evaporated to the core.

Saturn will have an insolation of 1.993 times what Earth gets now. Probably enough to evaporate much of the mass of it's moons. Uranus will get 0.492 times the amount of insolation Earth currently does, comparable to what Mars gets now (0.433). Neptune will get 0.21 times as much energy from the sun as Earth gets now.

I wonder what the effect of wavelength is. A red giant will emit most of its light in the red wavelength band. I don't know what influence that would have on evaporation.

Not much. It is just a question of power and temperature.

It would not be able to split water molecules into atoms nearly as fast. But at least at jupiter there will be plenty of heat to make entire water molecules escape the small gravity well of moons.