Here is the scientific stance on home run distances:
"According to three physicists who have worked independently and have written extensively on the science of baseball, the human limit for hitting a baseball at sea level, under normal temperatures and with no wind, is somewhere between 450 feet and 470 feet."
I think this is an interesting revelation because it changes what is considered a mammoth-blast. Until now, whenever I heard anything starting with 4-- I immediately dismissed it because it wasn't 500 or longer. The fact of the matter is that there probably have been one or two 500 foot home runs in MLB history. As the article states, this means that 460 feet is truly a monumental blast.