Earth-like Planet discovered !

The first Earth-like planet was discovered only 20 light-years away. In terms of cosmic distance that's damn close.
This is cool. All we need now is a way to travel there. Damn, this is getting to be like Firefly.

Links: http://www.cbc.ca/technology/story/2007/04/24/science-planet.html

http://www.dailymail.co.uk/sciencetech/article-450467/Found-20-light-years-away-New-Earth.html

Discuss this !

Awesome! Hope I live long enough for scientists to get absolute proof life exists outside our planet. And to those who say "well sure, primitive life, but that's no big deal" remember Earth had only primitive life for a long time....but look at what time eventually brings!

From what I read it's rather simple (well, OK, on an astronomical scale ) to prove life on distant planets. Once you get a look at the atmosphere, you can find the traces of photosynthesis by analyzing the components. Or something like that.

Anyway, that's the whole thing with planets. The window where water is liquid is SO small. I ain't saying that water is an absolute necessity for life but probably for life we can recognize as such.

Wow, what technique did they use to find this?

This article is over a year old and I could have sworn that we've discussed an Earth-like planet 20 light years from us already...

but yes, it is cool.

Orion drive (nuclear pulse drive) can give you up to about 10% of C if anyone would have the balls to build it.

Enough to reach alpha centauri within a human lifetime (40 years), but this system, not so (200 years).

We had a thread or two on this back when it first came out.

The bad news:

1. A planet with 5X Earth's mass would very likely result in a surface gravity that humans would find terribly uncomfortable, if not flat out unlivable.

2. The planet is so close to its primary that while it may fall into the 'habitable zone' in terms of temperature, in terms of radiation it might be a different story entirely.

3. A planet so close to its primary very well may be tidally locked. If it is, there is little chance that it has an atmosphere. If it has no atmosphere, it has no oceans. In this case, however, the high mass of the planet may work in its favor in terms of retaining a gaseous atmosphere.

The good news:

1. The evidence is slowly mounting that planets are the norm, not the exception in our galaxy.

2. If (1) is true, then it is almost statistically certain that there are hundreds of thousands of earth-like planets out there in the galaxy, some of which 'might' be life-bearing. Whether or not such life is 'compatible' with ours in terms of scale and biochemistry is an entirely different topic, but it would appear the odds do favor the notion that we are not alone.

3. These sorts of discoveries are vital to prompt further efforts to get 'out there', as well as develop and fly projects such as the TPF. With spectographic analysis we can, indeed, detect things such as chlorophyll, methane, and oxygen in the spectral lines coming from extrasolar planets.

^Given the planets size, wouldn't gravity be around twice Earths on the surface? The 5xmass gives you 5G for a planet Earth's size, the diameter increase would then reduce that back by (1.5*1.5), just over half.

I think I've got my math right there...

2g on the surface would be uncomfortable, at least for the first-generation of colonists, but not unlivable.

Most people can take up to 3.5 - 4g without blacking out, a bit higher in a g-suit, and higher again if their bodies are conditioned to it by repeated stimulation, i.e. fighter pilots who go through it a lot. Experienced fighter pilots with a g-suit can take up to about 9g without blacking out.

At 2g you could walk around readily enough, though a bit clumsily... a 170 pound person (earth weight) would weigh 320 pounds under 2g. There are already existing obese (or obscenely built, as with some obsessive bodybuilders) people who have more than twice the weight they should have for their height and natural build, but can still walk, and even run or jump a bit. Under 2g it would be a bit laborious... you'd be likely to get tired quickly. Also the amount and kind of things you could lift and carry would diminish, since everything would weigh more.

Oh yeah, tripping and falling would be a bitch. Broken bones nearly guaranteed. Remember, it's not just increased weight.. mass stays the same, the increased weight is due to greater gravity, and greater gravity has one effect that simply increased weight (due to increased mass in an earth level gravity field) would not have - increased acceleration during falls. Not only do you weigh a lot more, you're goin' down faster.

Second generation humans who grew up on such a world would be much more robust and suited to the conditions, since their bodies would be adapting to the pull of said gravity from the moment of birth (or even before birth). Denser, thicker bones and muscles etc. would come naturally as they grew.

I wonder if they have already developed a naming convention for new planets...?

Surface Gravity = G Mm/r^2

Where G = Newton's Constant
M= Mass of the planet
m = Mass of the object on the surface
r = planetary radius

So, the surface gravity will vary in direct proportion with the planet's mass but inversely to the square of the radius.

I'm not going to crunch the numbers but that's the numerical relationship involved.

This is true but Newton's equation doesn't address that- it assumes a relatively uniform density throughout. In order to calculate the surface gravity at any one spot you'd need to pick the spot, have an accurate 3D breakdown of the planet's desnity at each point, and then feed that hairy integral to a big Cray computer and wait.

I'm pretty sure that's incorrect, so long as all the mass in contained in a sphere below you then that wouldn't matter. In fact, if the Sun was to suddenly be converted into a black hole right now it would not alter Earths orbit one bit.

If one hemisphere was denser than the other or something similar then it would affect the gravity locally (as it does to a small extent on Earth as Marso has pointed out) but under any real scenario it would be unlikely to ever find a planet where it made a real appreciable difference.

Nup.

If that happened to the sun it wouldn't because while some of the suns mass would now be farther away, some would also be closer. The solar mass closest to us would have moved further away to be compressed into the center, but at the same time solar mass from the other side of the sun would have moved closer to us, cancelling out any difference.

As you correctly point out, it is the mass center that is important, you just weren't taking all of the mass into account. Indeed basic Newtonian laws say that in a gravitational collapse (such as the collapse into a black hole, or more specific to your original point, a planets mass being pulled into a dense core) the mass center will stay in the same place.

The verdict is still out whether there's intelligent life on Earth IMHO.

Well at least amoung prime ministers and presidents no intelligent life.

Irony.

anyone found an update on this article since the first one?

There's gotta be other M-class planets out there!

http://www.usatoday.com/tech/science/space/2008-09-30-cosmic-bubble_N.htm

So, if we do live in a special "cosmic bubble," there might be lots of planets that would be like us IF they were in a similar bubble. That doesn't sound probable though.

I, too, want other M class planets.

Interesting theory, although I think the bubble they are talking about would be much bigger than you think, it would have to encompass all the nearby galaxies at least.

It would have to be large based off what we know. We're finding out though that we don't know a whole lot. 300 years from now our descendants will mock us for being as ignorant as folks who in the past thought it rained worms.

Interesting theory. In some ways it is a more simple explanation than this 'dark matter' that nobody is able to detect or prove other than by the apparent absence of visible mass in the universe.

You can think that as much as you like, it doesn't make it true.

Technically yes, very small differences in the same way that the Earth has slight variations in gravity from point to point, but nothing you would ever be able to notice without sensitive instrumentation. Even then, the average surface gravity would be exactly identical.

If the mass is the same, there is no difference if you're on or above the surface. Gravity is only different if there's different densities at the same distance from the center of mass.

One word: Mascons.

That is talking about inconsistencies in the density throughout the mass, not uniform differences in structure. That is why it talks about locations on the surfaces having a variation in the gravitational strength at that point. No shuffling of how things are arranged inside the planet can alter the overall average surface gravity however.