During the two years that the Rosetta spacecraft stalked the comet, it observed cliffs that collapsed, boulders that moved and eruptions of dust and gas.
KENNETH CHANG, NY Times: Science
Thu, 03/23/2017 - 12:41pm
During the two years that the Rosetta spacecraft stalked the comet, it observed cliffs that collapsed, boulders that moved and eruptions of dust and gas.