Sean Johnson

A galaxy is more than just a stellar island. Surrounding it, far beyond the edge of the visible disk, hangs a tenuous cloud of gas. It barely emits light, but it is through this cloud that the galaxy breathes: drawing in fresh hydrogen to form new stars and expelling processed material after supernova explosions.

A charred lump the size of a fist is all that remains of a scroll from the library of the Roman city of Herculaneum. Buried by the eruption of Mount Vesuvius two thousand years ago, the text hidden inside has gone unread ever since. Physically unrolling such a scroll would turn it to ash. But now archaeologists no longer have to take that risk.