First Earth-Sized Exoplanet May Have Been Found

Adam Korbitz writes "New Scientist is reporting the extrasolar planet MOA-2007-BLG-192Lb — whose discovery was announced just last summer — may actually be the first truly Earth-sized exoplanet to be identified. A new analysis suggests the planet weighs less than half the original estimate of 3.3 Earth masses; the new estimate pegs the planet's size at 1.4 Earth masses. The planet orbits a small red dwarf star, some 3,000 light-years from here, at an orbital distance of 0.62 astronomical units, about the same distance as Venus from our sun. One significance of the planet's discovery is that it points to the probable ubiquity of smaller terrestrial planets in somewhat Earth-like orbits around red dwarf stars, the oldest and most numerous stars in the galaxy. Here is a video report from the discoverers."

Comments

Earth-sized != Earth-like

[Anonymous Coward]

Just because it's an earth-sized planet doesn't mean it's Earth-like. Red dwarf stars are very small (no more than half the mass of the Sun). They don't put out much energy so the habitable zones are very small and very close to the planet. Being so close to the sun makes it likely that the planet would be tidally locked (same side always facing the sun) which isn't so good for life. Finally red dwarf stars often have high stellar variation (sometimes fry you, sometimes freeze you), also not so good for life.

So exciting, but keep looking.....

http://en.wikipedia.org/wiki/Habitability_of_red_dwarf_systems

So?

[bradbury]

If you are familiar with the work of Charlie Lineweaver's group in AU, you would be aware that not only should Earth-like planets exist but that a significant number of them are older, and potentially more advanced than we are. This might then lead you to explore whether or not Matrioshka Brains (forms of civilizations significantly more advanced that our own exist.) And indirectly to an understanding that extremely advanced stellar civilizations have very different heat signatures (or detection signatures) from our own. Thus the detection of an earth-like planet is not that significant. The detection of a star going dark, signaling a civilization making a Kardashev-Type-I to a Kardashev-Type-II transition -- now that would be interesting.

Re:So?

[osu-neko]

If you are familiar with the work of Charlie Lineweaver's group in AU, you would be aware that not only should Earth-like planets exist but that a significant number of them are older, and potentially more advanced than we are.

Familiarity with Lineweaver's work does not make one "aware" of that "fact", it merely makes one aware that some people have argued that that is the case. :p

Lineweaver, Davis, and such have proposed a number of ideas which are intriguing, but it's all on very tiny and shaky foundations. Not saying they're wrong, but if they're reasonably close to right, that's more luck than anything, given the sample size of there real data it's all based on (e.g. estimating how many Earth-like planets develop life in their first billion years based on the one and only example we have of it happening).

Re:So?

[adavies42]

i once saw this basic argument used to infer the existence of workable ftl. it goes something like this:

1. conquering the whole galaxy (via generation ships or von neumann machines or whatever) takes only a few million years
2. we're unlikely to be the absolute oldest civilization in the galaxy
3. we do not appear to have been conquered
4. the only feasible way to block conquest is a federation with a prime directive
5. the only way to hold a federation together is ftl
6. therefore ftl exists. qed.

now obviously there are lots of holes in this, but i find it at least as compelling an answer to the fermi paradox as "they've all transcended"/"they're hiding in their dyson spheres".

Quick quiz

[The Bungi]

Since the strength of the gravitational field of a planet is a factor of its mass, and the gravitational pull on the surface is in direct relation to the distance from the center of the planet... could it not be possible to have a planet the size of say, Neptune, with a geological makeup similar to the Earth, that has a lower mass and therefore the acceleration at the surface is exactly 1g (as we understand it here on Earth). That is within the bounds of physics, is it not?

Or maybe the effective gravity is stronger, but the planet spins faster. Faster days as well?

The problem I guess would be the existence of a formation process that actually creates a planet with such a large surface but happens to be mostly rock instead of mostly gas (supposedly gas giants are "failed stars"). If it has a molten iron core, would it not collapse in on itself?

Interesting, imagine a planet with the surface composition and atmosphere of Earth (and supposedly biomass) but 10 or more times the surface. That would be amazing.