ripple

A simple ripple tank is the mainstay of every physics teacher's demo collection. The typical demonstration is done with a point light source of a little tungsten light bulb a few feet above the ripple tank. The ripple tank is in reality a shallow pan of water with a clear bottom. The ripples are observed by placing a sheet of paper a foot or so below the pan of water.

Haters can hate on the click bait words all they want, because the video above is all-but-literally mind-blowing, jaw-dropping and all the rest. Captured over the course of 4 years by the Hubble Space Telescope, it's a time-lapse that shows a very unusual star's 'light echo' rippling out through space in the most spectacular fashion.