Really nice image. My only crit, as `priteeboy pointed out, is the flames would only be seen upon entering an atmosphere. But that aside, it's a great image to view. Colours and composition are spot on!
I'd say they look more like burning meteors than comets. Comets until they hit the atmosphere have more white/blue tails But they still look cool The gas giant is nice too, a bit like a more calm version of Jupiter.