Originally posted by Juntai
True, that might make a difference, but we're given multiple comparisons by the author- comparison to 50x supernova, and comparison to a nebula. I doubt it's an baby one.
Coincidentally, there is nebulas 50 times the size of a supernova, and bigger.
There is just no way for Pa Kent to be able to differ between explosions larger than an atomic explosion. So he might as well have claimed that it was large enough to span a galaxy. The man is an old coot without any kind of logically conceivable way of determining the size. The entire story is narrated from his memory.