NASA plans major announcement on oceans beyond Earth

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      On Thursday (April 13), get ready for more big news from another part of the universe.

      That day, NASA has announced that it will hold a news conference "to discuss new results about ocean worlds in our solar system from the agency’s Cassini spacecraft and the Hubble Space Telescope".

      Seven scientists will speak, starting at 11 a.m. Pacific daylight time, and it will be broadcast live on the U.S. agency's website.

      NASA says on its website that it explores oceans on other planets and moons as part of its search for evidence of life elsewhere in the universe. 

      According to NASA, hydrogen was created by the Big Bang, which radically expanded the universe. And oxygen is in the core of stars far larger than the sun.

      Water is created when two molecules of hydrogen come together with one molecule of oxygen.

      This explains why water exists in gaseous form in the galaxy.

      "The Hubble Space Telescope peered into the Helix Nebula and found water molecules," NASA states on its website. "Hydrogen and oxygen, formed by different processes, combine to make water molecules in the ejected atmosphere of this dying star. The origins of our oceans are in the stars."

      In addition, water molecules have been detected around a 20-million-year-old star, Beta Pictoris.

      "Over billions of years, countless comets and asteroids have collided with Earth, enriching our planet with water," NASA states. "Chemical markers in the water of our oceans suggest that most of the water came from asteroids. Recent observations hint that ice, and possibly even liquid water, exists in the interiors of asteroids and comets."

      Nearly three-quarters of Earth is covered in water, but less than three percent is fresh water.

      Most of the fresh water is in polar caps and in glaciers, but they're melting as the Earth warms as a result of rising carbon dioxide levels in the atmosphere.

      "The Greenland ice sheet is melting at the rate of 287 billion tons a year, and the Antarctic ice sheet is losing 134 billion tons a year," NASA reports. "Both will be factors in sea level rise."

      Planets can lose water. According to NASA, Mars once has a protective magnetic field, but once that was lost billions of years ago, it lost 87 percent of its water. And Venus might have had the solar system's first ocean.

      "Venus lacks a strong global magnetic field, which on Earth, helps to protect our atmosphere," NASA states. "A runaway greenhouse effect raised temperatures enough to boil off the water, which escaped into space due to the solar wind."

      Scientists also believe that a subsurface salty ocean exists on Europa, Ganymede, and Callisto, which are all moons that orbit around Jupiter, as well as on Eceladus and Titan, which each orbit around Saturn.

      "Kepler-22b is the first planet in a confirmed orbit in a star's habitable zone—the region around a star where liquid water could persist on its surface," NASA states. "Kepler-22b is a 'super-Earth,' about 2.4 times Earth’s size. Scientists do not yet know if the planet has a rocky, gaseous, or liquid composition. It's possible that the world would have clouds in its atmosphere."