First Earth-Sized Exoplanet May Have Been Found 222
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."
Well... (Score:4, Interesting)
Settle Venus and Mars first. (Score:2, Interesting)
Earth-sized != Earth-like (Score:5, Interesting)
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? (Score:5, Interesting)
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.
Quick quiz (Score:5, Interesting)
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.
Re:So? (Score:5, Interesting)
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:When can I pack my bags? (Score:4, Interesting)
Sized? (Score:3, Interesting)
I'm used to size meaning volume...
Otherwise you might say a bullet is the size of 100 feathers...
Re:Quick quiz (Score:1, Interesting)
If the density is the same as Earth, then 10x the radius is 1000x the volume and hence 1000x the mass.
Gravity goes like GM/(r^2) so the increase radius partially cancels the increase in mass but not completely.
In the end, gravity is 10x stronger.
(Posting as AC because already started moderating ...)
Re:When can I pack my bags? (Score:2, Interesting)
3000 light years means that we are seeing it as it was 3000 years ago. If you could get to the speed of light right now, it would be 3000 years until you got there (assuming that the relative distance between us is roughly constant). But you can't go that fast, you'd have to go a lot slower than that.
In the next 3000 years we are sure to develop much faster methods of travel, so will will overtake you (i'll wave as we pass) and when you get there all the hot alien babes will be taken.
who cares about the discoverers? (Score:3, Interesting)
I want to see video of the planet.
Re:When can I pack my bags? (Score:4, Interesting)
This got me thinking:
If inhabitants there invented faster-than-light space travel, and arrived on Earth thousands of years ago. Eventually their civilization was destroyed by some freak natural disasters and all techs were lost.
We are just their descendants, now looking at our home planet?
Re:Ummm (Score:1, Interesting)
The problem isn't Earth - its humanity. And if we do get out there, we'll break that too.
Re:Settle Venus and Mars first. (Score:4, Interesting)
Venus will never be a good candidate for habitation unless we build platforms which "float" on its atmosphere's surface due to the close proximity to the sun. Wikipedia has some decent overview here: http://en.wikipedia.org/wiki/Colonization_of_Venus [wikipedia.org]
Mars is also quite small and does not hold onto its atmosphere very well (which coincidentally means it also doesn't have a strong magnetic field of it's own in which to protect potential inhabitants from solar radiation amongst other things (again due to its size)), so colonizing it will only really be possible if we build sealed enclosures on its surface or find a way to generate a LOT of atmosphere over a long time AND we find a way to protect our self from radiation from space in a feasible manner.
I am not an educated member in these related fields, but this is the information I have picked up while taking a passing interest in this stuff.
On top of that, finding other planets which are earth like does not have to happen in an either / or situation with attempting to colonize other planets. Both research paths can and are being pursued at the same time because it takes an entirely different scientist and research field to find extra-planetary bodies than it will to find a way to terraform one.
- Toast
Re:On the flip side... (Score:1, Interesting)
No need for any new technologies. Just stop fucking with the existing systems, wind the population down to 10m and enjoy. This is Eden and to not get that is very sad. The very concept of "it needs improving" is why we are so fucked today. See http://www.kansascity.com/news/world/story/986910.html
Re:Ummm (Score:4, Interesting)
It might take a few failed colonies at first, but eventually a society would evolve a way to ensure that happens. Perhaps mandatory civil service that involves external colony maintenance as a requirement for political office? Or maybe even the same for obtaining the voting franchise - a sort of Starship Troopers lite.
In fact, if you were a space-going race you probably wouldn't want to establish contact with a species that hadn't already gone through that winnowing out process. I would even go so far as to say that that difference might eventually lead to true divergence of humans into two species: the earth-bound and the space-faring.
If "we" get out there, the people that colonize another planet probably won't be the same "people" that are messing up Earth right now because those people wouldn't survive long enough to make it that far. Yeah, it's kind of an elitist view, but evolution is the ultimate meritocracy and, in very harsh environments, the people that forget that don't stay in the gene pool long.
Re:Earth-sized != Earth-like (Score:3, Interesting)
One possible way around the tidal locking problem is if the habitable planet is actually a satellite of a larger planet. Or the planet has a satellite like our moon.
The satellite would be tidally locked to its parent and I'd think that in a relationship like between the Earth and Moon there would be a tendency for them to get tidally locked.
Re:On the flip side... (Score:2, Interesting)
On the flip side, the spin-off technologies from making a sustainable habitat off planet would probably do wonders for improving the quality of life on planet.
If the spin-off technologies are so valuable, why not fund the research, skip making the actual trip, and wind up with better technology without going anywhere? Do everything except build the final vehicle and we save lots money and get cool technology.
Re:So? (Score:5, Interesting)
i once saw this basic argument used to infer the existence of workable ftl. it goes something like this:
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".