Feathers from the underground ocean
The earth is probably the only planet in the solar system that shows moisture. But astronomers believe that quite a lot of planets contain the entire ocean under the surface, which remains liquid due to the heat generated by gravity and radioactive decay. Potential candidates include Jupiter's largest moon Ganymede; Ceres, the largest object in the asteroid belt; and even Pluto, at the far end of the solar system. However, there are only two cases. Astronomers have direct evidence that these hidden oceans exist in the form of water column coming out of the surface, and only one of these cases is conclusive. In 2013, the Harbert Space Telescope discovered the plumes of Jupiter's icy Jupiter, Europa, but never appeared since then. By contrast, Saturn's icy two - guard two appears to have produced more normal plumes, one of which was Cassini's actual flying spacecraft in 2015. Cassini used his airborne mass spectrometer to confirm that plumes are water and contain simp