Gone Exo-Fishing



I’m taking a little break alongside the Atlantic but can’t leave exoplanets et al completely behind. 

Water worlds are inferred, or known, to be present and perhaps not uncommon in the galaxy.  And there is reason to conclude that they may have much more water than Earth.  Although 70.8% of all Earth’s surface is covered in water, H2O accounts for just some 0.05% of Earth’s mass.

Some animations and illustrations of what these aquaworlds might look like:

Depiction of a world completely covered with ocean.
(NASA Kepler Mission/Dana Berry)

A 2017 study published in The Monthly Notices of the Royal Astronomical Society suggests that Earth is in a minority when it comes to smaller planets, and that many habitable planets may be greater than 90% ocean. There are worlds where more than 10% of the mass may be water. This may be the case, for example, for all the six innermost planets orbiting the star Kepler-11 (David A. Aguilar (CfA)


Watery exoplanet with exo-moon. (Phys.org, CBC11, CC By-SA )


Exoplanet scientists have been studying whether the potential glint from a planet would tell them that there is water on the surface. This artist’s concept shows Kepler-62f, an exoplanet in the habitable zone of its host star, which is located about 1,200 light-years from Earth in the constellation Lyra. Researchers think Kepler-62f may be a waterworld. (NASA/Ames/JPL-Caltech)


Many waterworlds may be ice covered with a global ocean underneath, like Saturn’s moon Enceladus. NASA’s Cassini spacecraft completed its deepest-ever dive through the icy plume of Enceladus on Oct. 28, 2015.


Artist rendering of TRAPPIST-1f in the seven-exoplanet Trappist-1 system in constellation Aquarius. The color comes from orbiting a red dwarf star. With added fisherman. (NASA)

Marc Kaufman
Marc Kaufman is the author of two books about space: "Mars Up Close: Inside the Curiosity Mission” and “First Contact: Scientific Breakthroughs in the Search for Life Beyond Earth.” He is also an experienced journalist, having spent three decades at The Washington Post and The Philadelphia Inquirer. While the “Many Worlds” column is supported and informed by NASA’s Astrobiology Program, any opinions expressed are the author’s alone.

To contact Marc, send an email to marc.kaufman@manyworlds.space.

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