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10 Things: April 10
10 Apr 2017
(Source: NASA)

Earth is the ultimate ocean planet (we know of), but our solar system turns out to have water in some surprising places, with five ocean-bearing moons and potentially several more worlds with their own oceans. In addition, multiple worlds likely had oceans in the past, but lost them!

NASA will discuss new results about ocean worlds in our solar system from the agency's Cassini spacecraft and the Hubble Space Telescope during a news briefing at 11 a.m. PDT (2 p.m. EDT) on Thursday, April 13. Meanwhile, here are 10 things you need to know about ocean worlds:

1. The Original "Alien Ocean"
NASA's Galileo spacecraft (1989-2003) detected the first evidence of an ocean beyond Earth under the ice of Jupiter's icy moon Europa.

2. Lost Oceans
There are signs Mars and Venus once had oceans, but something catastrophic may have wiped them out. Earth's natural force field -- our magnetosphere -- acts like shield against the erosive force of the solar wind.

3. Earth, the Original Ocean World
The search for life beyond Earth relies, in large part, on understanding our home planet. Among the newest Earth ocean explorers: NASA’s Cyclone Global Navigation Satellite System (CYGNSS) – a constellation of microsatellites that will make detailed measurements of wind speeds over Earth’s oceans to help understand hurricanes. The spacecraft have moved into their science operations phase.

4. Sister Ships
It's fitting the first mission to explore an alien ocean is named in honor of fast-sailing clipper ships of old. NASA's Europa Clipper spacecraft will seek signs of habitability on Jupiter's moon Europa.

5. Game Changer
Scientists expected Saturn's moon Enceladus to be a tiny, solid chunk of ice and rock. But not long after arriving at Saturn, NASA's Cassini spacecraft started making an incremental series of discoveries, eventually confirming that a global subsurface ocean is venting into space, with signs of hydrothermal activity.

6. Why Ocean Worlds Matter
"The question of whether or not life exists beyond Earth, the question of whether or not biology works beyond our home planet, is one of humanity's oldest and yet unanswered questions. And for the first time in the history of humanity, we have the tools and technology and capability to potentially answer this question. And, we know where to go to find it. Jupiter's ocean world Europa." – Kevin Hand, NASA Astrobiologist.

7. More Alien Oceans
Scientists think Jupiter's giant moons Ganymede and Callisto also hide oceans beneath their surfaces. Elsewhere in the solar system, scientists hope to look for hidden oceans on far-flung worlds from Ceres in the main asteroid belt to Pluto in the Kuiper Belt.

8. Cold Faithful(s)?
Thanks to NASA's Cassini orbiter we know the tiny moon Enceladus is venting its ocean into space in a towering, beautiful plume. The Hubble Space Telescope also has seen tantalizing hints of plumes on Jupiter's moon Europa. Plumes are useful because they provide samples of ocean chemistry for oceans that could be miles below the surface and difficult for spacecraft to reach. It's like they're giving out free samples!

9. Titanic Seas and Ocean
Saturn's moon Titan not only has liquid hydrocarbon seas on its surface. It also shows signs of a global, subsurface saltwater ocean – making the giant moon a place to possibly look for life as we know it and life as we don't know it… yet.

10. Oceans Beyond
Several of the thousands of planets discovered beyond our solar system orbit their stars in zones where liquid surface water is possible – including Proxima-b, a rocky planet orbiting the star nearest to our own.

BONUS: Adopt a bit of YOUR Ocean World
NASA invites everyone to help us celebrate Earth Day 2017 by virtually adopting a piece of Earth as seen from space. Your personalized adoption certificate will feature data from NASA’s Earth-observing satellites for a randomly assigned location, much of it ocean (it is 70 percent of the Earth’s surface after all!). Print it and share it, then explore other locations with our interactive map and get even more Earth science data from NASA’s Worldview website.

Visit to adopt your piece of the planet today!

See previous editions of 10 Things.