Alien Life May Swim On Earth-Like Planets: Oceans Cover Habitable Exoplanets

Don't bet on humans finding aliens just walking around on another Earth-like planet -- they'll more likely be swimming. That's the assertion of one scientist, who predicts most of the exoplanets we find in habitable zones around their stars are almost entirely covered in water. Earth itself is about 70 percent water on its surface, but the alien planets are likely "dominated by oceans spanning over 90 percent of their surface area," a study in the journal Monthly Notices of the Royal Astronomical Society speculated. Author Fergus Simpson of the University of Barcelona's Institute of Cosmos Sciences writes that such extensive water coverage would explain why some exoplanets that astronomers have discovered have not been as dense as expected. As experts search for planets that may harbor extraterrestrial life, they are usually looking for planets that are within a certain distance of their host star, called the habitable zone.