[2] Prometheus consists of a 28-kilometer-wide (17 mi) volcanic pit named Prometheus Patera and a 100-kilometer-long (62 mi) compound lava flow, all surrounded by reddish sulfur and circular, bright sulfur dioxide (SO2) volcanic plume deposits.
[4] Later that year, the International Astronomical Union named this feature after a Greek fire god, Prometheus.
Between the Voyager encounters and the first observations by Galileo, a 6,700-square-kilometer (2,600 sq mi) flow field was emplaced.
The SO2-rich plume is generated as lava at the western end of the flow field covers sulfur dioxide frost, heating and vaporizing it.
[8] Prometheus' plume has been observed by both Voyager spacecraft, Galileo, and New Horizons, at every appropriate imaging opportunity.