One of my roommate’s middle school science students asked this question the other day, and she was stumped. The question came up while they were discussing a probe that is about to or has hit the atmosphere.
Jupiter’s atmosphere is primarily hydrogen and helium, correct? Is it possible that a sufficiently sizable incendiary source could actually ignite the atmosphere, either accidently or intentionally? Are there other factors that are missing that would be required for something like this to occur?
Unlikely to the point of impossibility…
You’d need unbelievable amounts of oxidizer to make it burn, unless you were able maybe compress it enough to turn it into a small star. I can’t imagine how we’d ever take on a project that big, though.
If you think back a few years (1994), Jupiter was struck by a series of chunks of comet Shoemaker-Levy. The results were spectacularly incandescent but Jupiter failed to ignite. So I’m thinking the answer to your question is “no”.
What’s missing is oxygen. Hydrogen won’t burn without it. There are lighning storms on Jupiter quite often and the planet seems to do just fine.
Well, if I’m not mistaken, a comet, or pieces of one, struck Jupiter some time ago, creating an explosion the size of earth. No blown-up planet, though.
Jupiter is often considered to be a ‘failed star’, that is, a celestial body whose mass and/or density was insufficient to trigger nuclear fusion and burn. Perhaps it is this reason why it could not simply ‘explode’ by tossing a lit cigarette 
into the atmosphere.
No- No O2 (or other oxidizer) to ‘burn’ it. Also there are multiple lightning strikes and other things crashing into it that burn up in the atmopshere.
Also there is not enough pressure to cause the hydrogen to fuse so no thermonuclear reaction either. If Jupiter was bigger it’s own gravity might have started nuclear fusion and we’d have a binary system
Yeah, but frankly the prosepects of Earth being sandwtiched between two stars doesn’t sound so great, what with the constant daylight (sans eclipses) and all 
Just watch 2010: The Odyssey Continues to see how some aliens managed it (although the movie is admittedly thin on the actual details of how that worked).
Actually, I was thinking of just that movie (and book). The aliens appear to have done it through a process called “magic”, best I can tell.
Yes, I know: Any technlogy sufficiently advanced…yada yada…
Would that be the case for sure? Jupiter is about 5 times farther from Earth than the Sun is. How much light would a small star at that distance add to our nights? How big would the disc of that star appear in the sky?
We would only be between the 2 for about 1 season per year, 2 additional seasons they would cut nighttime about 1/2 of what it is now and wouldn’t effect the final season all that much (in terms of longer daylight).
Wouldn’t Jupiter kick-off a massive wave of solar particles, radiation, and the like when if first ignighted, assuming we could actually cause that to happen?
Would that be dangerous, even possibly fatal, to life on earth if the Earth were not hidden on the far side of the sun when the wavefront reached us?
How long might such solar ejecta be dangerous after ‘ignition’? Would the earth be periodically swinging through a hotzone for several years afterwards? Maybe decades?