描述
For decades, scientists didn’t know why Enceladus was the brightest world in the solar system, or how it related to Saturn’s E ring. Cassini found that both the fresh coating on its surface, and icy material in the E ring originate from vents connected to a global subsurface saltwater ocean that might host hydrothermal vents.
Before Cassini arrived at the Saturn system, planetary explorers only had hints that something interesting might be happening at Enceladus. Pictures from the Voyager spacecraft in the 1980s indicated that although this moon is small—only about 310 miles (500 kilometers) across—its icy surface is remarkably smooth in some places, and bright white all over. In fact, it’s the most reflective body in the solar system.