Jupiter and the Galilean Satellites (image) Southwest Research Institute Caption Jupiter (right) and the Galilean satellites (right to left) Io, Europa, Ganymede, and Callisto. Cutaways show the interior states of Ganymede and Callisto after many impacts by icy planetesimals during the late heavy bombardment. Colors represent density, with black showing the rocky core (with a density 3 g/cm^3), blue showing mixed ice and rock (densities 1.8 to 1.9 g/cm^3) and white showing rock-free ice. Credit Southwest Research Institute Usage Restrictions Embargoed until 1 p.m. Eastern, Jan. 24, 2010. Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.