Newly Discovered Habitable Extra-Solar Planet

The University of California, Santa Cruz has this press release: Newly discovered planet may be first truly habitable exoplanet. Here are some excerpts, with bold added by us:

A team of planet hunters led by astronomers at the University of California, Santa Cruz, and the Carnegie Institution of Washington has announced the discovery of an Earth-sized planet (three times the mass of Earth) orbiting a nearby star at a distance that places it squarely in the middle of the star’s “habitable zone,” where liquid water could exist on the planet’s surface. If confirmed, this would be the most Earth-like exoplanet yet discovered and the first strong case for a potentially habitable one.

Interested? Sure you are. Let’s read on:

To astronomers, a “potentially habitable” planet is one that could sustain life, not necessarily one that humans would consider a nice place to live. Habitability depends on many factors, but liquid water and an atmosphere are among the most important.

No doubt. We continue:

“Our findings offer a very compelling case for a potentially habitable planet,” said Steven Vogt, professor of astronomy and astrophysics at UC Santa Cruz. “The fact that we were able to detect this planet so quickly and so nearby tells us that planets like this must be really common.

Here’s where it’s located:

The paper [to be published in the Astrophysical Journal] reports the discovery of two new planets around the nearby red dwarf star Gliese 581. This brings the total number of known planets around this star to six, the most yet discovered in a planetary system other than our own solar system. Like our solar system, the planets around Gliese 581 have nearly circular orbits.

Gliese 581? Where is that star?

Gliese 581 [is] located 20 light years away from Earth in the constellation Libra …

There’s a lot more information at that link to UC Santa Cruz, but we’ll skip to the end:

“If these are rare, we shouldn’t have found one so quickly and so nearby,” Vogt said. “The number of systems with potentially habitable planets is probably on the order of 10 or 20 percent, and when you multiply that by the hundreds of billions of stars in the Milky Way, that’s a large number. There could be tens of billions of these systems in our galaxy.”

So there you are. Plug that into your Drake equation. If this discovery is what it seems to be, then life is likely to be everywhere!

Update (creationist view): Newfound Extra-Solar Planet: No Chance for Life.

Update: See Earth-like Planets May Be Very Common.

Update: See Discoveroids Ecstatic Over Astronomy Error.

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13 responses to “Newly Discovered Habitable Extra-Solar Planet

  1. That is pretty awesome news, but we still need a few more parameters for the Drake equation.

  2. Phil Plait also has a post about it over at Bad Astronomy. He says the planet’s almost certainly tidal locked (one side always facing the sun).

  3. As I understand it, the planet is in the “life zone” and big enough to hold an atmosphere, and therefore a candidate to have water. We shouldn’t get too excited before we even know if there is an oxygen in the atmosphere.

    He says the planet’s almost certainly tidal locked (one side always facing the sun).

    So no surfing on Planet Goldilocks. Bummer.

  4. You have to think that if there are at least two habitable (or potentially habitable) planets within 20 light years of each other, there must be a vast multitude of planets in the universe that could support carbon-based life. And since detection of these extrasolar planets is so exquisitely difficult, there’s gotta be way more than one such planet within 20 light years. Even within the time frame of modern astronomy, we have just begun discovering these planets.

    So, is there life out there? Of course, we can’t tell for sure yet, but given the probabilities, almost certainly. But what sparks the imagination is not just life, but intelligent life. It took 3.8 billion years of evolution for earth life to get to the point of being able to develop technology, so you’d think we would need long periods of stable conditions for life to get to this point elsewhere.

    Well, it happened here, so it could just as easily (or just as “difficultly”) happen elsewhere. It’s a BIG universe.

  5. Oxygen may not be necessary– plenty of organisms use chemosynthesis to survive.

    But yeah… that discovery is super cool!!!

  6. The next few years are going to be very exciting. I’m still holding out for the discovery of small rocky planets around one or both stars in the Alpha Centauri system. (I’m not including Proxima Centauri, which probably could not sustain a habitable planet).

  7. Ed says,
    ” I’m still holding out for the discovery of small rocky planets around one or both stars in the Alpha Centauri system.”

    Double- and multiple-stars systems pose problems for habitabilty. Gravitational perterbations would probably eject any planets, and even if that didn’t happen, temperatures on the planets could vary over too wide a range, since the planets would be at widely varying distances from their parent stars.
    Still, there are many, many suitable single stars of the right type to support life in our galaxy alone, and there are hundreds of billions of galaxies — and that’s just the observable universe.

  8. retiredsciguy says:

    Double- and multiple-stars systems pose problems for habitability.

    Not necessarily. A bit more mass (well, a lot more) and Jupiter could be a star. So we could have had a double-star system right here. If that had been the case, Earth might still have life on it.

  9. The orbital mechanics might not change that much, but the earth would have two sources of fusion. I don’t know if you’d see water-based life. Maybe steam-based. But this is why it’s so hard to estimate the probabilities, too much we don’t know.

  10. Curmy says, “Not necessarily.”

    Hey, I didn’t say life would be impossible in a multiple-star system, just that “double- and multiple-stars systems pose problems for habitabilty. ”

    Gabriel Hanna is correct in pointing out that the earth would have two sources of fusion. This would make earth’s temperature fluctuate through a much greater range than we experience with just the sun. It would be pretty hot when we were between the two (as we are right now), and a lot cooler when we were on the far side of our orbit from Jupiter. How much hotter would depend on how big a star Jupiter was. And if Jupiter were large enough, that *would* screw up our orbital dynamics, potentially ejecting us from the Solar-Jovian System.

    What raised the issue in the first place was Ed’s mention of the Alpha Centauri System, which is a three-star multiple system. Going from memory here, I think Alpha and Beta Centauri Alpha Centauri A and Alpha Centauri B are approximately the same size, both being somewhat larger than the sun, while Proxima Centauri is a quite small red dwarf. I don’t know enough about orbital dynamics to say whether you could have an earth-sized planet in a stable orbit in the “Goldilocks Zone” in that system, but it just seems less likely.

  11. Correction — it’s not Alpha and Beta Centauri, it’s Alpha Centauri A and Alpha Centauri B. Beta Centauri, also called Hadar, is unrelated to the Alpha Centauri system.

  12. Guys, it’s possible for the Alpha Centauri system to have planets in stable orbits – around both stars. “A” could have planets out to about the orbit of Mars in our system. The problem has been in working out how they would form. That’s been a problem in our system as well, and the current models are not simple, with gas giants migrating to their current orbits, for example. A binary system would be even tougher to solve, but that doesn’t mean there is not a solution.

    A and B orbit in a fairly stretched ellipse, and come as close to each other as the Sun is to Saturn. If we had another sun where Saturn is, it would be effectively a bright star in our sky. Look at how much warmth Titan receives from the sun, for example. Spacecraft traveling beyond Mars orbit cannot use solar arrays for power, due to insufficient sunlight. In other words, the existence of the other star would have no appreciable effect on our climate. This would apply to a putative Centauri planet as well.

    Centauri A is just a little larger than our sun, but still a comfortable G type star, about the same age as our sun and probably formed in the same nebula. Centauri B is a bit smaller and cooler, being a K type star, but obviously the same age and constituents.

    I agree that the odds are low that there are sizable planets in circular orbits, given the eccentricity of the stars, orbits around each other, but it’s not impossible. We will probably have the technical means to answer that question within the next 5 years or so. I have my fingers crossed!

  13. retiredsciguy

    Ed, Thanks for the enlightenment.