Enceladus, Pandora, and Rings (Oh, My!)


Saturn’s moon Enceladus is backlit by the Sun in this Cassini spacecraft image from 2009. The dramatic lighting shows of the plumes that continuously spew into space from the south pole of 500 km diameter moon. The icy plumes are likely fed by an ocean beneath the ice shell of Enceladus. They supply material directly to Saturn’s outer, tenuous E ring and make the surface of Enceladus as reflective as snow. Behind Enceladus, Saturn’s rings scatter sunlight toward Cassini. Beyond the rings, the night side of the 80 km diameter moon Pandora is faintly lit by light reflecting off of Saturn.

Image Credit: NASA

R Sculptoris


This image, which was taken by the Very Large Telescope at the European Southern Observatory, shows an extremely small section of the sky: approximately 20×20 milliarcseconds. For comparison, Jupiter as seen from Earth has an angular size of roughly 40 arcseconds. The ghostly image is of a distant, pulsating red giant star known as R Sculptoris, which is 1200 light-years away in the constellation of Sculptor. It’s a carbon-rich asymptotic giant branch star that is nearing the end of its life. As the end comes, low- and intermediate-mass stars cool off, create extended atmospheres, and lose a lot of their mass—before becoming spectacular planetary nebulae.

One odd feature of R Sculptoris is its dominant bright spot which seems to be two or three times brighter than the rest of the star. Astronomers speculate that R Sculptoris is surrounded by giant “clumps” of stellar dust that are peeling away from the shedding star. This bright spot is probably a region around the star with less dust, allowing more light to escape.

Image Credit: ESO