This illustration depicts the three giant planets orbiting the Sun-like star Kepler 51 as compared to some of the planets in our solar system. These planets are all roughly the size of Jupiter but a very tiny fraction of its mass. This means that the planets have an extraordinarily low density, more like that of Styrofoam rather than rock or water, based on new Hubble Space Telescope observations. The planets may have formed much farther from their star and migrated inward. Now their puffed-up hydrogen/helium atmospheres are bleeding off into space. Eventually, much smaller planets might be left behind. NASA's Kepler space telescope detected the shadows of these planets in 2012-2014 as they passed in front of their star. There is no direct imaging. Therefore, the colors in this illustration are imaginary.
