Monday, September 21, 2015

What If the Planet Jupiter Exploded?

Stupid question, asked of a stupid University of Cambridge astronomy professor:

QUESTION:    WHAT would happen to Earth if Jupiter in a hypothetical situation exploded?  What kind of magnitude would it be? And how would the astronomical community report that back to nations around the world? Would the asteroid belt be perturbed in any way?    Thank you...

ANSWER:   It depends in part what you mean by 'exploded'.  The solar system planets are quite widely separated, so at least initially, the effect would be rather small.  The orbits of the other planets would remain close enough to their present orbits that only astronomers would be able to tell the difference, and this will be true whatever type of 'explosion' you want.  As for any immediate, direct effects of the 'explosion', remember that space is a vacuum and so shock waves (sound, earthquakes, etc.) can't propagate.

If we go with a minimal 'explosion' and just magically cause Jupiter to vanish then the only other thing we would have to worry about is what happens to its moons and the asteroids.  The large moons that orbit close to Jupiter would probably all simply be ejected from the solar system and not pose any threat to anyone.  Some of the smaller ones further out might go onto elliptical orbits around the Sun, but there are not that many of them so the chance of a collision would be quite small.

The asteroid belt would likely remain much as it is, interactions with Jupiter actually generally serve to destabilise asteroids rather than the other way around.  The only possible cause for concern would be the Trojan asteroids, which share Jupiter's orbit and lead or follow it by 60 degrees.  These occupy stable regions created by the gravity of Jupiter, so if Jupiter were to disappear some of them might become unstable and come into the inner solar system.  This would likely be a long process rather than a fast one so we would probably have a reasonable length of time to deal with any new asteroid that appeared on a collision course with Earth and not be much worse off than our current situation.  In short, other than the disappearance of Jupiter from the sky, most people probably wouldn't notice the difference.

On the other hand, if you want a 'Death Star' style explosion rather than just a planetary vanishing act things would be a little different.  Jupiter is extremely massive, and all of that mass suddenly flying around the solar system is going to have some rather interesting effects.  Now most of the mass of Jupiter is gas (primarily hydrogen and helium), which the Sun would eventually blow away through X-ray radiation and the solar wind (though it might take some time to do so).  What effect the gas has depends partly on how far the explosion spreads it and so how dense it is, it could potentially exert drag on some asteroids, particularly the Trojans, and cause them to spiral in to the inner solar system.
If Jupiter has a rocky core (we aren't actually entirely certain if it does), then that would cause additional problems.  The core of Jupiter might be as more then 10 times the mass of Earth, by comparison the whole asteroid belt is less than 0.1% the mass of Earth.  Turning all of that into rubble and throwing it across the solar system would cause utter havoc, the conversation between a whole leader and an astronomer would probably go something like this:

Astronomer:  Jupiter has exploded, the core, which incidentally we know now was 10 Earth masses, has been pulverized and thrown out across the solar system.

World Leader:  That doesn't sound good, is any of it going to hit us?

Astronomer:  We haven't determined the exact numbers yet, but we expect the impacts to start within a year.

World Leader:  Within a year!?  What kind of damage are we expecting?

Astronomer:  It will probably start fairly localised, but the surface will reach saturation quite rapidly.

World Leader:  Saturation?

Astronomer:  Imagine carpet bombing the entire planet with the largest nuclear weapons you have.

World Leader:  Oh... Can we do anything about it?

Astronomer:  Nope.

World Leader:  So we're doomed then?

Astronomer:  Pretty much, yeah.

If Jupiter doesn't have a core, or if it is pulverized into small enough pieces in the explosion (think dust), then it might not be so bad.  The gas and dust would probably partially block out the Sun and cause and ice-age, though material raining down into the atmosphere might also cause Earth to heat up, so it might get hotter even with the Sun being dimmed.
Either way the environment would be pretty screwed up but some people might survive.


LL said...

Massive Jupiter (and Saturn) ask as lode stones, absorbing comets and bits of flotsam and jetsam that come screaming out of the Kuyper Belt and Oort Cloud. If they weren't there, we'd be taking a lot more damage from those sources (not counting perturbation of the asteroid belt or from death star style debris). Likely life on Earth would be snuffed out.

The Local Malcontent said...

I remember when comet Shoemaker-Levy broke up and was predicted to slam into Jupiter back in the early 1990s, LL- (I only remember just getting out of OU, so maybe during the alcohol flood of 1992?)

Anyway, there was some concern that these pieces of comet would somehow ignite Jupiter's frozen helium and hydrogen atmosphere, producing a second sun in the sky.

In the light of all of the sudden "end of world" prophecies lately, I agree, we'd be smashed if Jupiter were to explode, I just don't see that happening... OHH WAIT- JOVIAN GLOBAL WARMING~~~~~~! Lol

~have yourself a good day!

Col. B. Bunny said...

Great. One more thing to worry about.