(Image credit:  JPL-CALTECH / BJÖRN JÓNSSON / NASA) Could Uranus and Neptune be full of rocks? One new study thinks so. Uranus and Neptune are two planets that have historically been classified and thought of as "ice giants," orbiting far out in the freezing edges of our solar system . But it's possible that our understanding of these planets' makeup could be totally off, and their atmospheres could be full of rocks, researchers suggest in a new study. These two planets both have inner rocky cores surrounded by icy mantles enveloped by a thick atmosphere that has been thought to contain hydrogen, helium and methane gases as well as silicate clouds. In some high pressure areas, the gaseous atmosphere becomes fluid — but the results of this study suggest these atmospheres could also be littered with rocks.…