Video courtesy YouTube user wlsoundman.
Like me, you’ve probably seen lots of photographs of Cherenkov radiation (Wikipedia), which is the striking blue glow that surrounds nuclear fuel rods submerged in water. It’s caused by charged particles travelling through the water at a speed faster than the speed of light in water (which is about 75% percent of the speed of light in a vacuum).
But this video of Penn State’s Breazeale nuclear reactor “pulsing” is the first time I’ve ever seen any moving pictures of the phenomenon, which are somehow way more impressive. And since this is a phenomenon few of us will ever have an opportunity to witness first-hand, the 15 seconds it takes to watch the video definitely count as time well spent in my book. Note how the blue glow persists for some time after the reactor itself has been shut off.
[Thanks, William Beaty!]