

The First rocky planet outside our solar system confirmed - edw519
http://spacefellowship.com/2009/09/16/smallest-exoplanet-is-shown-to-be-a-solid-rocky-world/

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hughprime
Very interesting, and big news.

As well as being the first extra-solar rocky planet discovered, it's also the
largest rock we know about, beating out the previous record holder (Earth) by
a factor of five.

We've known about a bunch of these super-Earths (1-10 Earth masses) for some
time, but there's been some disagreement over whether they were large rocks or
small Neptunes. Now we know that large rocky bodies are at least possible,
this tells us something interesting about planetary formation.

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geuis
We've had proof of large rocky bodies for 4.5 billion years. MVEM. Also
physical traces of the remains of the planer building, post dust cloud
phase(asteroids/comets/impactor sites on every body in the system). Cosmology
works under the theory that our local implementation of physical laws is the
same elsewhere in the observable universe. What we are finding now at the
level of exo planetary bodies is independent confirmation of the local
phenomena we have already observed.

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hughprime
_We've had proof of large rocky bodies for 4.5 billion years_

By large, I mean significantly larger than Earth. We know about rocky bodies
up to one Earth mass. We also know about low-density ice-gas bodies of 14
Earth masses or more. Bodies in between these two known types of planet,
though, we're pretty ignorant about -- are they Earthlike or Uranuslike? Now,
while N=1 makes for lousy statistics, we know that at least this one is
Earthlike.

We're actually still astonishingly ignorant about how planets form in the
first place, so anything we can find out about the compositions of exoplanets
is pretty valuable.

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anigbrowl
Neat, but I wish we were bombarding Mars and/or venus with extremophile
bacteria, tardigrades and what'all else to see what sticks.

Of course, there's always the hope that as we ID more earth-like planets one
of them might prove to be broadcasting on a wavelength we can receive.

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yan
Actually, NASA goes through pretty great lengths to make sure we don't
contaminate Mars with bacteria.

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anigbrowl
Understood and agreed - I don't really want to contaminate a planet-sized
experimental sample before we have wrung as much knowledge out of it as
possible. At the same time, though, I think we should balance the
possibilities of knowledge acquisition with those of resource exploitation.

For example, if we successfully conduct 5 exobiologically-oriented missions
over the next 25 years without making any breakthroughs, then maybe we should
just Try Something Else. Ditto for Venus:
[http://en.wikipedia.org/wiki/Observations_and_explorations_o...](http://en.wikipedia.org/wiki/Observations_and_explorations_of_Venus)

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DanielBMarkham
Cool catch -- thanks.

Along these lines, wasn't there a space telescope launched a few months back
specifically to find extrasolar planets? Any news on how that is coming along?

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hughprime
The Kepler mission? Yep, that's just getting started. So far all they've
published is that they've tested it against a known gas giant and shown that
yes, the instrument can detect it:

<http://kepler.nasa.gov/press/earlyresults.html>

Once the mission gets started in earnest it's mostly a waiting game. It'll be
sitting there, watching a bunch of stars, and waiting to see whether a planet
just happens to pass in front of one of 'em. This is unlikely for any
particular planet, since it requires that the orbital plane of the planet just
happens to be parallel to the line of sight between us and the star, and it'll
also only happen once every "year", but we should be able to pick up a few
eventually.

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DanielBMarkham
I'm very enthusiastic about this mission -- it should answer a lot of
questions. And hopefully pose even more.

How prevalent are earth-like planets? Planets in binary systems? Do Jupiters
"clear out" space for inner rocky planets? etc.

It's all good stuff, and extremely fascinating.

