, so it must be either a relatively icy body or very porous "rubble pile" or, more likely, something in between. Recent measurements of infrared spectra from the Subaru telescope suggest that the moon indeed contains hydrous minerals, indicating that it cannot have formed in its current position, since the hot primordial Jupiter would have melted it. It is therefore likely to have formed farther from the planet or to be a captured Solar System body. No images were taken during this flyby (Galileos cameras had been deactivated due to radiation damage in January 2002), and the resolution of other available images is generally low. Amalthea radiates slightly more heat than it receives from the Sun, which is probably due to the influence of Jovian heat flux (<9 kelvins), sunlight reflected from the planet (<5 K), and charged particle bombardment (<2 K). This is a trait shared with Io, although for different reasons. Named geological features There are four named geological features on Amalthea: two craters and two faculae (bright spots). The faculae are located on the edge of a ridge on the anti-Jupiter side of Amalthea. Craters are named after characters in Greek mythology associated with Zeus and Amalthea, faculae after locations in associated with Zeus. Relationship with Jupiter's rings Due to tidal force from Jupiter and Amalthea's low density and irregular shape, the escape velocity at its surface points closest to and furthest from Jupiter is no more than 1 m/s and dust can easily escape from it after, e.g. micrometeorite impacts; this dust forms the Amalthea Gossamer Ring. During its flyby of Amalthea, the Galileo orbiter's star scanner detected nine flashes that appear to be small moonlets near the orbit of Amalthea. Because they were sighted only from one location, their true distances could not be measured. These moonlets may be anywhere in size from gravel to stadium-sized. Their origins are unknown, but they may be gravitationally captured into current orbit or they may be ejecta from meteor impacts on Amalthea. On the next and final orbit (just an hour before destruction), Galileo detected one more such moonlet. However, this time Amalthea was on the other side of the planet, so it is probable that the particles form a ring around the planet near Amalthea's orbit. Views to and from Amalthea From Jupiter's "surface"—or rather, from just above its cloudtops—Amalthea would appear very bright, shining with a