First habitable Earth like planet outside Solar System discovered

Zeenews.com ^ | April 24, 2007

[Sopater]

Munich, April 24: An international team of astronomers from Switzerland, France and Portugal have discovered the most Earth-like planet outside our Solar System to date.

The planet has a radius only 50 percent larger than Earth and is very likely to contain liquid water on its surface.

The research team used the European Southern Observatory’s (ESO’s) 3.6-m telescope to discover the super-Earth, which has a mass about five times that of the Earth and orbits a red dwarf already known to harbour a Neptune-mass planet.

Astronomers believe there is a strong possibility in the presence of a third planet with a mass about eight times that of the Earth in the system.

However, unlike our Earth, this planet takes only 13 days to complete one orbit round its star. It is also 14 times closer to its star than the Earth is from the Sun.

However, since its host star, the red dwarf Gliese 581, is smaller and colder than the Sun – and thus less luminous – the planet lies in the habitable zone, the region around a star where water could be liquid!

“We have estimated that the mean temperature of this super-Earth lies between 0 and 40 degrees Celsius, and water would thus be liquid,” said Stéphane Udry from the Geneva Observatory, Switzerland and lead-author of the paper in the journal Astronomy and Astrophysics.

“Moreover, its radius should be only 1.5 times the Earth’s radius, and models predict that the planet should be either rocky – like our Earth – or covered with oceans,” he said.

“Liquid water is critical to life as we know it and because of its temperature and relative proximity, this planet will most probably be a very important target of the future space missions dedicated to the search for extra-terrestrial life. On the treasure map of the Universe, one would be tempted to mark this planet with an X,” added Xavier Delfosse, a member of the team from Grenoble University, France.

According to the research team, the host star, Gliese 581, is among the 100 closest stars to us, located only 20.5 light-years away in the constellation Libra (“the Scales”).

The star has a mass only one third that of the Sun. Such red dwarfs are at least 50 times intrinsically fainter than the Sun and are the most common stars in our Galaxy. Among the 100 closest stars to the Sun, 80 belong to this class.

“Red dwarfs are ideal targets for the search for such planets because they emit less light, and the habitable zone is thus much closer to them than it is around the Sun. Any planets that lie in this zone are more easily detected with the radial-velocity method, the most successful in detecting exoplanets,” said Xavier Bonfils, a co-worker from Lisbon University.

Bureau Report

[JamesP81]

So a 150 lb man here would weigh about 333 lb there. It’s a big difference, it would certainly be inconvenient for us, but it wouldn’t be lethal for a wide variety of earthborn species.

Not immediately, no, but I think that long term ill effects would likely be the real problem.

[JamesP81]

That’s okay, the colony ship will have a eugenics program to select for skeletal and muscle strength, and will gradually increase its axial rotation to raise the simulated gravity during the trip, which should take about 6400 years travelling 600 mi/sec (approx. escape velocity for the solar system). (Kind of shows how irrelevant this ‘news’ is when you think about it.)

Really illustrates the bottom line: if we want to explore the stars, a system of moving faster than lightspeed will be required. There's a device called an Albucierre (sp) drive that, mathematically, is feasible but it would require exotic matter to function. Same goes with using those theoretical wormholes that crop up in Einstein's General Relativity theory. Again, making use of them, if the mathematical models are right, would require use of exotic matter.

[Centurion2000]

That's an enormous assumption with no empirical data in our solar system (that we've found yet) to back it up.

Well, the empirical data so far suggests that liquid water indicates life. (One data point)

[MeanWestTexan]

“Are those accurate numbers? Do we really have any technology which will continuously accelerate for 5 years at a given rate, with a mass low enough to let it peak at .75 SOL?”

Yes, we do have the ability -— or could with not that much effort -— but we are not economically or socially willing to put de facto nuclear weapons into space (a pulse jet could do it -— but it is essentially blowing up small nukes one after the other with a big shield).

Indeed, such technology was banned by international treaty after the “Rainbow” tests of upper-atmospheric nukes back in the 1950s.

And the probe you dicuss would be much easier than a people-probe -— no (or rather much less) concerns with G-forces and none of the life-support baggage related to people -— food, water, air, radiation protection, etc.

[Sopater]

Somewhere out there is a world like our own, with blue skies, fields of grain, vast forests, lofty trees, and soaring peaks. Someday, we will find our long dreamt-of Terra Nova. Our job is to keep the dream alive until then.

The odds that this is true is infinitesimally small. Our job is to "fill the earth and subdue it" (Gen 1:28).

[MeanWestTexan]

“The thing is, unless it was launched from Antarctica or the poles, the radiation it would put into the air was estimated to kill a lot of people indiscriminately around the world.”

That’s what the moon is for. Or even orbit.

Wonder if there is a suitable nearby asteroid that could have an engine stuck on it.

[RightWhale]

you will never be disproven in your own lifetime

Telescopes capable of analyzing planets like this, earthlike, are nearing launch. This and hundreds more will be analyzed for proper atmosphere as well as the presence of life within a decade.

[RightWhale]

First. Major discovery, not unexpected although sooner than expected.

[HeadOn]

Man! Where were all of you when I was screwing up my Physics labs 30 years ago?

From a quick read, I missed the radius, OK? Gimme a break... I’ll do better, I promise.

(I’d weigh 488 pounds...)

[spunkets]

"What’s the formula (see some of the previous questions)?"

F=m*a. The acceleration(a) of gravity is:

a_earth = F/m = g*m_earth/r_earth²

The planet is 5X as massive and the radius is 1.5X bigger, so:

a_planet = g*5*m_earth/(1.5*r_earth)² = 5/1.5² * a_earth = 2.2*a_earth

Then see #104 and #106. The equatorial and polar radii are different, which would be due to spin. I just stuck a ruler up to the screen. A better measure(this AM, LOL) would be,

r_polar / r_equatorial = 1.083

A plastic body would find itself in a shape where the forces at the surface are equal. Since there's no spin at the poles, only at the equator, Equal surface scceleration gives,

a_polar = a_equatorial = 2.2(1-0.083) = 2.0

That means the centifugal acceleration at the equator is 0.2, and opposes the acceleration of gravity. So any mass m will be attracted to the surface with a force(F) of m*2*a_earth

[spunkets]

"So what about Godebert's question? What effect would this have on atmospheric pressure, assuming an Earth-like atmosphere since it's supposed to be habitable."

See #150. The atmosphere just represents a mass. Pressure is force/area, so the fator is 2.0. So, for all things equal, the atmospheric pressure there would be twice Earth's, or 29.4psi.

[spunkets]

"it would seem that all the weight bearing joints would be under far more stress and would deteriorate much more quickly."

Right, and talk about a ton of bricks in the AM! LOL! The circulatory and repiratory systems would be stressed too.

[metmom]

Good Lord, my arches are in bad enough shape as it is, too. And when the arches go, the ankles go, which takes out the knees, then the hips, ...

[ukie55]

And what moron declared this planet habitable?

[spunkets]

THe journalist that titled their piece.

[newguy357]

Well, the empirical data so far suggests that liquid water indicates life. (One data point)

That is utterly illogical. You cannot draw any kind of generalization from a single point. You could just as well say "if it has uranium buried in the ground, it has life" because we also have one data point testifying to that. Yes, we have water, and yes, it is necessary to life on our planet, but both of those statements are irrelevant to any effort to generalize.

[RightWhale]

Venus is habitable by this standard. So is Mars. But, jumping from ‘water’ to ‘life’ is a leap. If the atmosphere contains oxygen, say 20%, that would be a strong indicator, but water occurs commonly and is not an indicator for life although life would be dificult without it.

[gimme1ibertee]

Just in time,since we’re doomed to burn this one up any day now. (/sarc)

[SunkenCiv]

Someone answered above, but anyway, the volume of the Earth is about 29 per cent of this newly found planet. I didn’t read the whole thing — is density estimated?

[spunkets]

from the better guess of the planet's radii given in 150. The planet's angular velocity, or spin is ω=v/r. For Earth(e) and the planet(p) the radial acceleration(a) is:

a = v²/r

Where v is the tangential velocity of a surface particle. Then,

v_e = sqrt(0.003*r_e*a_e) = 0.055 * sqrt(r_e*a_e)

and

v_p = sqrt(1.5*r_e*0.2*a_e) = 0.55 * sqrt(1.5*r_e*0.2*a_e)

The ratio of the planet spins is ω_p / ω_e = (v_p * r_e) / (1.5*r_e*v_e) = 0.67*v_p/v_e

Substituting gives,

ω_p/ω_e = 0.55/0.055 * 0.67 = 6.7

So, the planet spins 6.7 times faster than Earth, and it's days are 3.6hrs long. Since the period of one rev around the star is 14 earth days, it's probably not tidally locked.