Black holes and Light Echoes

A black hole wreaks all sorts of havoc in its cosmic neighborhood, pulling in and stretching out matter, spewing jets and slowing time to a near stand-still. Now astrophysicists have added a new phenomenon to the black hole's list of tricks: Light echoes.

Black holes are often surrounded by spinning discs of burning gas that can emit X-ray bursts. Because the black hole warps the surrounding space-time so intensely, though, the photons from a single one of these bursts don't always arrive at the same time. Read more on the new phenomenon, announced at this week's American Astronomical Society Meeting, here.—Gregory Mone