Scientists recently found even more evidence that Jupiter's icy moon Europa is hiding an enormous ocean of saltwater.
To say Europa's ocean is vast would be an understatement. If all of Earth's water — oceans, lakes, rivers, rain, clouds, and more — were combined into one blob, it'd be just half as large as Europa's liquid reservoir. (And Europa is about the size of Earth's moon.)
Scientists think Europa's ocean might even be habitable to alien life.
"If there's life at Europa, it'd almost certainly be an independently evolved form of life," Bob Pappalardo, a planetary scientist at NASA's Jet Propulsion Laboratory, previously told Business Insider. "Would it use DNA or RNA? Would it use the same chemistry to store and use energy? Discovering extraterrestrial life would revolutionize our understanding of biology."
But Europa is just one of many ocean worlds in the solar system, including Enceladus, Pluto, Titan, and Ganymede.
To figure out how much liquid water and ice these worlds have compared to Earth, Business Insider contacted Steve Vance, a planetary scientist at NASA's Jet Propulsion Laboratory. Vance closely monitors research about ocean worlds to create estimates of ice thickness, ocean depth, and other parameters.
The graphics below use Vance's data and other sources to show the probable volume of liquid water on eight known ocean worlds besides Earth.
Volumes are shown in zettaliters (ZL), a unit that's equal to 1,000,000,000,000,000,000,000 liters or 1 billion cubic kilometers. Earth harbors about 1.335 ZL of water, according to the National Oceanic and Atmospheric Administration.
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Enceladus vs. Earth
Enceladus is a relatively small moon of Saturn, at just 314 miles in diameter — about as wide as the state of Arizona. But its ocean sprays water into space. NASA's Cassini spacecraft confirmed the ocean's existence after its arrival in 2004, later detecting and flying through the water plumes to "taste" them.
Note: Because Earth has a very small amount of ice relative to other ocean worlds, this graphic and the following ones only depict our planet's liquid water.
Triton vs. Earth
Triton is a moon of Neptune that's some 2.8 billion miles from Earth. Voyager 2 is the only spacecraft ever to fly by, measure, and photograph Triton. Those sequential photos showed that Triton has "cryovolcanoes" that spew out water and ammonia.
Dione vs. Earth
Dione is a small, icy moon of Saturn. Scientists determined in 2016 that — like Enceladus — Dione likely has a subsurface ocean.
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