# What will a future cold and "dead" Jupiter look like? [duplicate]

I heard Jupiter is dying like getting smaller. For example, from Guillot et al. 2004 3: The Interior of Jupiter (also here):

(Jupiter)... is still contracting at the rate of ~3 cm per year while its interior cools by ~1 K per million year.

When will it completely die, how much smaller will it be then, and what will it look like?

• "I heard.." Where did you hear this? Commented Feb 18, 2021 at 23:25
• Tomorrow. Because as God of all Gods he looks with dismay at the blasphemous people. [Citation needed]. Commented Feb 18, 2021 at 23:54
• "I heard that..." questions are often closed when they don't include a reference to the source from where it was heard, like a book or a video or a website. There is a Wikipedia article for Jupiter, perhaps you can find something in there to both support something like this, and from which you can ask a more specific question?
– uhoh
Commented Feb 19, 2021 at 0:03
• update: I couldn't find anything in Wikipedia, so I've added a supporting reference for your premise. I think this is an interesting question!
– uhoh
Commented Feb 19, 2021 at 0:11
• Jupiter is still sucking in comets and asteroids and such. I guess it must be ejecting matter faster than it's absorbing it. Losses to solar radiation almost certainly have to increase as the Sun goes Red Giant, but perhaps they will lessen to almost nothing when it becomes a white dwarf? Commented Feb 19, 2021 at 0:20

One can calculate a rough Kelvin timescale for the ratio between binding energy and the blackbody power of the surface to estimate how quickly it cools down (this number will be nudged by the above considerations a bit, so it is an order of magnitude estimate): $$\tau_{Kelvin}=\frac{3GM^2}{20\pi\sigma R^3 T^4}.$$ For Jupiter this timescale is 54 billion years.
As the universe cools eventually it becomes a ball of layered solid degenerate matter, with a frozen hydrogen crust. This will take longer than $$\tau_{Kelvin}$$ due to various mild heating processes like crystallization heating, tidal heating from the moons, possibly dark matter annihilation, and other low-energy processes that keep objects warmer than the CMB.