NASA’s Cassini spacecraft has discovered an unusual cloud of particles around Enceladus, one of Saturn’s many moons. They could be stray particles from Saturn’s outermost E-ring or a previously unseen dust cloud. The discovery is so interesting to researchers that they’ll have Cassini change its altitude on its next flyby – scheduled for July 14 – lowering the spacecraft so that it passes only 175 km (108 miles) above the surface of the moon.