Petrology is a field of science in which scientists study the compositions of rocks and minerals and interpret their geologic history. A common graph petrologists use is the “pyroxene quadrilateral.” These graphs, like photos of space, can reveal an understanding of the remotest parts of the solar system.
On June 3, Hayabusa2 ended use of its ion engines, for now, and is coasting the remaining distance toward Ryugu. It's using an optical navigation camera to image the asteroid's position against a field of background stars to help it navigate.
One of the Cassini mission's goals was to figure out how long a day on Saturn is. We still don't know. A new paper reports a measurement of the rotation period of Saturn that is different from past measurements.