People have long wondered what life was first like on Earth, and if there is life in our solar system beyond our planet. Scientists have reason to believe that some of the moons in our solar system—like Jupiter's Europa and Saturn's Enceladus—may contain deep, salty liquid oceans under an icy shell. Seafloor volcanoes could heat these moons' oceans and provide the basic chemicals needed for life.

Similar deep-sea volcanoes found on Earth support microbial life that lives inside solid rock without sunlight and oxygen. Some of these microbes, called thermophiles, live at temperatures hot enough to boil water on the surface. They grow from the chemicals coming out of active volcanoes.

Because these microorganisms existed before there was photosynthesis or oxygen on Earth, scientists think these deep-sea volcanoes and microbes could resemble the earliest habitats and life on Earth, and beyond.