I n our solar system, only one planet is blessed with an ocean: Earth. Our home world is a rare, blue jewel compared with the deserts of Mercury, Venus, and Mars. But what if our sun had not one but two habitable ocean worlds? Astronomers have found such a planetary system orbiting the star Kepler-62. This five-planet system has two worlds in the habitable zone — the distance from their star at which they receive enough light and warmth that liquid water could theoretically exist on their surfaces. Modeling by researchers at the Harvard-Smithsonian Center for Astrophysics (CfA) suggests that both planets are water worlds, their surfaces completely covered by a global ocean with no land in sight. “These planets are unlike anything in our solar system. They have endless oceans,” said lead author Lisa Kaltenegger of the Max Planck Institute for Astronomy and the CfA. “There may be life there, but could it be technology-based like ours? Life on these worlds would ...