Eruptions on Io. Galileo spacecraft image of two volcanic eruptions on Io, a moon of Jupiter. A 120 kilometrehigh (km) plume from the Pillan Patera volcano appears as a grey patch at Ios lower left edge. The second, from the Prometheus volcano, is visible as a plume (grey) & its shadow (black) at centre. Prometheus may have been erupting cont inuously for at least 18 years, whilst this is the first Pillan Patera eruption ever seen. Ios vol canoes are powered by the strong internal tidal forces created because the moon orbits so close to Jupiter. Image taken by Galileos solid state ima ging camera at a range of 600,000km on 28 June 1997. The smallest visible objects are 2km across.
