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Astronomers Claim Discovery of Earth-like Planet
Raver32 writes "A team of astronomers announced they have discovered the smallest and potentially most Earth-like extrasolar planet yet. Five times as massive as Earth, it orbits a relatively cool star at a distance that would provide earthly temperatures as well, signaling the possibility of liquid water. 'The separation between the planet and its star is just right for having liquid water at its surface,' says astronomer and team spokesperson Stephane Udry of the Observatory of Geneva in Versoix, Switzerland. 'That's why we are a bit excited.' But researchers do not yet know if the planet contains water, if it is truly rocky like Earth, which might make it hospitable to life as we know it, or whether it is blanketed by a thick atmosphere. 'What we have,' Udry says, 'is the minimum mass of the planet and its separation" from its star.'"
That's only if the radius from the centre of the objects is the same. Remember, gravity decreases as a function of the square of the distance.
Anthropic principle: We see the universe the way it is because if it were different we would not be here to see it.
TFA is dated 24 April, 2007 -- I'm pretty sure that this is old news.
For you maybe, but anything that evolved in that environment would be really strong on this planet, be able to leap...wait, what was the name of that planet?
Can you imagine the women, why they'd be build like a brick shi...cue the Commodores.
Politics is the art of looking for trouble, finding it everywhere, diagnosing it incorrectly and applying the wrong fix.
Mass alone says very little about the surface gravity of a planet - you need to know the radius of the object to make any statement about its surface gravity. Earth's moon has slightly over a percent of the mass of Earth, but about 1/6g surface gravity. Mars has only about 10% of the mass of Earth, while having 1/3g surface gravity.
I think that in planetary terms we can safely assume 5x mass will create an environment of roughly 5g ... maybe give or take 20%. Enough to ensure that the simple act of getting out of bed would be a gruelling ordeal.
Another problem I noticed after actually reading TFA:
Gliese 581 c, orbits at one fourteenth the distance between Earth and the sun. But the red dwarf is 50 times cooler than the sun. The group estimates that the planet would experience temperatures in the zero-to-40-degree-Celsius (32-to-104-Fahrenheit) range.
It is my understanding that red dwarfs, while generating reduced heat and light output, produce solar flares that are almost as intense as those produced by a G class star. So if a planet exists in the habitable zone it is also exposed to periodic sterilizing blasts of charged particles.
Maybe if we're lucky the planet happens to have a really strong magnetic field ... then we just have the crushing g load to contend with.
If libertarians are so opposed to effective government, why don't they all move to Somalia?
From the blurb itself, it's five time the size of earth, it's revolving around a cooler sun than earth, and it might not have liquid water or a thick atmosphere. Yeah, that's exactly like earth!
You're missing the point. By Earth-like they mean telluric planet, as in, not a gas giant. That's all. And that matters because until now we haven't found so many of them, most of the planets we've found were gas giants orbiting close to their star. But as time goes by we find ever decreasingly large planets that get closer and closer to the Earth in size.
You just got troll'd!
Since Drake's equation needs to know the proportions of stars with planets, it would require us to have known negative results as well as known positives in order for it to give any meaningful results.
At the moment, we can say there are a few hundred planets, out of maybe a few thousand stars that we've scanned, but for the stars where we haven't found anything, we don't know for sure whether that's because there isn't anything there, or because we just aren't looking hard enough.
Andy
Invade!
--- What?
To calculate the gravitational effect of a massive sphere, its whole mass can be
:-)
considered accumulated in its center as long as you are outside of it.
So the gravitational acceleration indeed only depends on mass an distance.
Mathematical fact.
Neat additional trivia:
- Inside a hollow sphere, there is no gravitational effect by the sphere's mass - it cancels out exactly.
That's why
- Inside a massive sphere, gravitational acceleration increses linearly with the radial distance to the center.
(the mass increases with r^3 as you get further out, its effect decreases by 1/r^2 - and as it can be considered
concentrated in the middle, you get an increase by a factor of r^3/r^2 = r
Gravity is fun
All this of course only for constant density.
``No, we can even measure how surface gravity varies from g=9.78 m/s2 to g=9.82 m/s2 when moving from the equator towards a pole. And this is because Earth is not perfectly round, the people at higher latitudes are closer to the center of Earth and fall faster.''
No, that's because they drink more alcohol there.
Please correct me if I got my facts wrong.
The odds against it happening elsewhere are ... well ... astronomical.
The universe contains a very large number of elsewhere.
I think that in planetary terms we can safely assume 5x mass will create an environment of roughly 5g ... maybe give or take 20%. Enough to ensure that the simple act of getting out of bed would be a gruelling ordeal.
I don't know about you, but getting out of bed is a grueling ordeal at any gravity for me!
I think that in planetary terms we can safely assume 5x mass will create an environment of roughly 5g ... maybe give or take 20%. Enough to ensure that the simple act of getting out of bed would be a gruelling ordeal.
Another problem I noticed after actually reading TFA:
No, it would not. It would need to be much denser than Earth for that to happen. This is basically impossible for an object of that mass.
Assuming roughly Earth like density (which is quite plausible), Radius will scale like Mass to the 1/3, while gravity scales like mass / radius squared. This works out to about 1.7 times Earth gravity at the surface.
When they say "nearly the size of earth" they're speaking in an astronomical scale, which would qualify something 5-times as large as the earth as 'nearly'. It's not composed of gold or other heavy metal.
!#&*
Oh for god's sake, people! Do a little math.
Let's assume that the average density of the earth-like planet is the same as Earth. (It wouldn't be an earth like planet if it were significantly different.) Then we can use the volume of the sphere to relate the mass and the surface radius. Since M = 4/3 * \pi * R^3 * \rho, where \rho is the density, it is easy to see that the surface radius goes like the cube root of the mass. Putting this into Newton's equation, we can see that a = GM/R^2 means that the surface gravity is also going to go like the cube root of the mass. If the mass is five times that of Earth, then the surface gravity will be the cube root of 5 greater than Earth's or about 1.7 times Earth normal.
Taking differences in the mean density into account is no more difficult, but I leave that as an exercise for the reader.
It's a poorly written and shite article, but the box off to the side says:
One of two newly discovered exoplanets is nearly the size of Earth...
So, assuming they're talking about the same one, it should be roughly 5 times our gravity.
Not so. If the planet has twice the diameter of earth, that falls well within the category of "nearly the size of Earth" for astronomers. Since gravity decreases proportionally to the square of the distance, gravity would be only 5/(2^2) times as strong as on Earth, an increase of a mere 20%.
If it has approximately the same density as earth, then since volume of a sphere increases proportionally to the cube of the radius/diameter, it would have 5^(1/3) times as large a diameter as earth, which is about 1.71 -- even closer to the size of our Earth. It would also wind up with gravity 1.71 times as strong, since 5/((5^(1/3))^2) == 5/(5^(2/3)) == 5^(1/3).
If it's less than 14 Earth masses it's rocky. Simple as that ;-)
You just got troll'd!
Says you.
We don't know what it's composed of, and it *could* be solid gold. It *could be* heavy metal.
I personally believe it's composed entirely of soft rock. Chances are very slim that it's composed of top-40 pop or country&western.
"Trolls they were, but filled with the evil will of their master: a fell race..." -- J.R.R. Tolkien on Olog-hai
Forget the proportion of stars with planets. Fl is the real unknown. Why assume all planets that can support life will develop life? What if life is actually pretty rare? Try plugging in values less that 1 for Fl (0.1, 0.01, 0.001) and you'll get some disappointing results from this equation. Trying to quantify something with so many unknowns seems pretty silly to me. On the other hand maybe life isn't rare, but that's just me being hopeful.
Win a signed Stephen Carpenter ESP Guitar from the Deftones: http://def-tag.com/?r=0008781
No, no, no. Fill it with hairdressers, tired TV producers, insurance salesmen, personnel officers, security guards, management consultants, and telephone sanitizers.