@Oldgreg Maybe the atmospheres were high in oxygen and other flammable gasses and when they collided the atmospheres flew out into space and the collision ignited them
There is an estimated 400 billion star in the Milky Way, our Galaxy.
Fire needs Oxygen to ignite
There is an estimated 160 Billion planets in our Galaxy alone! Just imagine how many there are in the entire universe!
@tothemyers Suppose that the planets were individually slightly under the critical mass for nuclear fusion. If they both merged they could theoretically "ignite"(undergo fusion). I could see this working. For example, Jupiter is so massive that it produces infra-red radiation just by contracting under its own weight. The two planets colliding would have to be truly massive though...
Its actually pretty neat if you unpause.
@tothemyers Assuming there is an infinite number of universes in the multiverse, it is impossible for it not to be happening at all points in time. Assuming there is only our universe, it is still almost impossible for it not to happen every day.
Also, if pressures, temperatures and mass were to reach as certain point, the planet(s) would ignite, possibly creating an explosion, however not neccessarily as a result of impact.
Schmolendevice is partially correct - those are both gas giants, so there would be no explosion, just mixing of gasses. However, you have no way of confirming this happens every day, even if it does.
well because they're so big, there may be fusion between the planets as the collide :) know your physics
planet, Y U NO displace gas giant instead of explode!!!!!