Tying a smoke ring in a knot sounds impossible - but University of Chicago physicists have done something similar by creating a vortex knot for the first time, in a container of fluid.
Remember when the "automated teller machine" seemed like a brilliant invention?
ATMs allowed us to access cash immediately, even if it was 9 at night or Sunday afternoon.
NASA's Cassini probe has spotted a vast vortex over the south pole of Saturn's moon Titan, triggered by the moon's move into winter.
Respects to Lauren Weinstein. We don't often do How To videos, but this one is mandated.