On Jan 11, 12:10=A0pm, Allen Thomson <thoms...@[EMAIL PROTECTED]
> forwarded:
> ...The team found that super-Earths would be more geologically
> active than our planet, experiencing more vigorous plate tectonics
> due to thinner plates under more stress.
This just begs the question of what the actual research is, since
*that* conclusion is something my N190 students have been asked to
deduce on an exam. Square-cube laws are remarkable commonplace in
nature.
> Earth itself was found to be a borderline case, not surprisingly
> since the slightly smaller planet Venus is tectonically inactive.
And again, one wonders who wrote the press release, and if the authors
got to approve or veto it. Calling a planet who's surface is among the
youngest in the solar system & shows fold belts and grabens, as well
as a host of volcanoes and large-scale lava flows "tectonically
inactive" is, well,... stretching it. It's true that doesn't seem to
show terrestrial plate-style tectonics, but then again, as another
poster mentioned, a complete lack of water appears sufficient to
explain that.
> If super-Earths are as common as observations suggest, then
> it is inevitable that some will enjoy Earth-like orbits, making
> them excellent havens for life.
Uh-huh. Right. I wonder who's doing the study on model ocean depth,
and the possible impacts of a global 50 km deep ocean would have on
the development of life.
> "If a human were to visit a super-Earth, they might experience a bit
> more back pain, but it would be worth it to visit such a great tourist
> spot," Sasselov suggested with a laugh.
<grin> And if you think it cost a lot for a ticket to LEO, just
imagine what it's going to cost to launch out of a superterrestrial
gravity well.
> Rapid plate tectonics would provide less time for mountains and
> ocean trenches to form before the surface was recycled, yielding
> mountains no taller and trenches no deeper than those on Earth.
Huh? Can somebody name for me a major mountain chain that has been
destroyed by tectonics? You know, like the Rockies? Or the
Appalachians? Mountains don't get subducted - that's why they're
mountains. Due to the stability of the low-density root under a
upthrust mountain system, I can think of good reasons why mountains on
larger, high-gravity world would be smaller... in fact, again, this is
a problem I often assign to undergrads in a general studies course.
> Even the weather might be comparable for a world
> in an Earth-like orbit.
Yes, because gravity has nothing to do with the structure of the
atmosphere... well, except for compressional heating, the lapse rate,
and the scale height. Which influence just about everything else.
> For more information, contact:
Perhaps, a group of loose-knit amateur worldbuilders that have been
casually thinking about this since early USENET. Sigh... well, at
least I can use this as an example to my students of "you can out-
think this press release all on your own".
--
Brian Davis
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