can gas planets or titan catch fire

[rockinreel]

If we chunk a ball of fire towards the gas planets or Titan, why wouldn't they catch fire since they are made up of almost exactly the same gases as the sun? (and methane liquid rivers for Titan's case)

Why doesn't nebulas catch fire or anything in space? Why does it take a nuclear fusion to catch the sun on fire? or is the Sun actually on fire or does it just glow and radiate heat?

Midway, Georgia

[cran]

If you mean 'catch fire' as on Earth, then you'll need to throw in plenty of free oxygen as well...

[Ilya]

If we chunk a ball of fire towards the gas planets or Titan, why wouldn't they catch fire since they are made up of almost exactly the same gases as the sun? (and methane liquid rivers for Titan's case)

Why doesn't nebulas catch fire or anything in space? Why does it take a nuclear fusion to catch the sun on fire? or is the Sun actually on fire or does it just glow and radiate heat?

The Sun is not "on fire" in Earth sense of the world -- there is no combustion going on because there is no oxygen. Ditto for gas giants, Titan, and nebulae. Sun is hot because of nuclear fusion, and none of the others you mentioned have enough pressure to sustain fusion.