In the Dec. 23 & Jan. 6 SN: Our top stories of 2017, grounded pterosaur hatchlings, protectors of the Dead Sea Scrolls, a counterintuitive metamaterial, neutron star sizing, arrow of time reversed, E. coli in flour and more.
WATCHING LIKE A HAWC The HAWC experiment near Puebla, Mexico, uses more than 300 tanks of water to detect the signatures of gamma rays. Its new observations have reignited a debate about the source of unexplained antimatter particles from space.
LYING IN WAIT Huge tubs of water (one shown) at the Pierre Auger Observatory in Argentina reveal the tracks left as cosmic particles zip through them.
SPOT OF BOTHER The same complicated sunspot spat out seven flares from September 4 to 10. This image shows in ultraviolet light the second-largest flare (bright flash at right), which was emitted on September 10.