Moonshine

The closest ever look at Jupiter’s small inner moons shows that one of them
has an enigmatic bright streak some 50 kilometres long. Blurry photos taken by
the Voyager spacecraft two decades ago showed bright regions on
250-kilometre-diameter Amalthea. Pictures from the Galileo spacecraft, which
show details as small as two kilometres, now reveal one bright region which is
long and narrow. Its nature remains unknown, says Damon Simonelli of Cornell
University in New York State: it could be ejecta from a crater, or the crest of
a ridge.