We all know what water is. And what rock is. The difference is crystal clear. Well, here on Earth it is. But on other worlds? The difference might not be so clear. Among the hundreds of billions of stars in the Milky Way are who-knows-how-many exoplanets. Some number of them will be ocean worlds, completely … Continue reading Deep Down in Ocean Worlds, it’s Difficult to Tell Where the Oceans End and the Rock Begins