Death Star, what size is it?

Even if no mention is made of the Death Star's diameter, certain clues allow us to estimate it. For example, upon first seeing the Death Star, Luke mistakes it for a "small moon". Obi-Wan Kenobi and Han Solo confirm his observation: it is as big as a moon and significantly bigger than a space station. In our own solar system, moons and other sizeable asteroids vary from a few tens to some thousands of miles. Ceres, the solar system's largest asteroid, has a diameter of 580 miles (934 kilometers); Ganymede, Jupiter's biggest satellite, measures 3,278 miles (5,276 kilometers); Mimas, a satellite of Saturn, 244 miles (392 kilometers); the smallest satellites of Jupiter and Saturn have a diameter of about 12 miles (20 kilometers). We can effectively compare the Death Star to the planet Endor. In preparing their attack on Endor's generator, the rebels view a holographic image from which we can estimate that the Death Star's diameter is about a twelfth of Endor's. We just have to figure out the size of the latter!