Geoscience Reference
In-Depth Information
Oceans Undreamed
We are getting ever closer to discovering a multiplicity of far-distant
ocean worlds, some perhaps life-bearing. 180 Planets, we know, are
commonplace in the distant heavens. The next generation of satellites
and telescopes will find and examine numbers of Earth-sized planets
in the habitable zone, and will glimpse evidence of atmospheres,
oceans, and perhaps signs of life itself, via planetary chemistries
pushed out of equilibrium.
By then we should also have learned more about the hidden ice-
covered oceans of such nearer bodies as Europa, Triton, and Callisto
(where liquid water has been smuggled far beyond the normal habit-
able zone by the power of tidal energy), as well as understanding the
history of the oceans that seemingly long ago covered, however
briefly, the surfaces of our near neighbours Mars and Venus.
Each of these planets, present and past (relatively), near and far, will
have oceans quite as various and complex as our own. We see them
now as simple images, cartoons almost—blank canvases to which we
hope to add detail. Those far oceans will be stirred by currents and by
differences in temperature and chemistry, each in a specific pattern
and combination, and each different—some of them very different—
to the patterns and moods we see in our oceans. There will be differ-
ent flavours of ocean out there too. We cannot imagine that any of
those oceans will be of pure water. Rather, they will be complex
chemical cocktails of dissolved salts and minerals—and of organic
compounds too—some dilute, others more concentrated than even
the dense brines of the Earth's Dead Sea.
Those far oceans will not be constant, but will evolve through time
as their parent planets and stars evolve, either gradually or suddenly
and catastrophically. They will, over geological timescales, change in
volume, shape, temperature, and chemistry, some waxing larger, others
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