Rock-hard planet on planet action

The first detected “mini-Earth” and an Earth-sized planet with a water-vapour atmosphere are two of five planets found orbiting Kepler-20. Image: NASA/Ames/JPL-Caltech.

Two weeks ago Kepler gave us its first probable earth-like world orbiting the habitable zone of a sun-like star. This week it’s not one but two, count ’em two, small and probably rocky worlds. And these guys are tiny by exoplanetary standards:

(AstronomyNow) — A rocky exoplanet smaller than Earth, and its neighbouring Earth-sized world with a thick water-vapour atmosphere, have been detected around a Sun-like star already known to host three larger planets.
The planets were detected by NASA’s Kepler spacecraft, which watches for tiny dips in brightness of thousands of stars as a planet transits in front of them, temporarily blocking out a miniscule fraction of their light. One of the new planets identified around 1,000 light year distant Kepler-20 – Kepler-20f – has a radius almost identical to Earth at 1.03 Earth radii, and the other is just 0.87 Earth radii – smaller also than planet Venus – and is the smallest exoplanet ever identified around a Sun-like star.


  1. The Lorax says

    I’m a little disappointed; the “thick water-vapor atmosphere” has NOT been detected, at least according to that article. It even states that it is merely possible speculation, given certain circumstances that we cannot detect.

    This may sound pedantic, but I’d like for them to report the facts, and keep the speculation out of the first paragraph. I know they’re trying to hook people into reading the article (the article writers have to make a living, after all), but there’s a huge, huge difference between “finding a rock the size of Earth” and “finding a rock the size of Earth with a water-vapor atmosphere”.

  2. jamessweet says

    I do have to say, this makes me somewhat more optimistic about the possibility of humans one day making contact with intelligent aliens. A search such as this for likely planets, followed up by an Active SETI-type program seems like it ought to do the trick if life is at all common on life-hospitable planets.

    I had earlier figured there was little to no chance, given how far out in the galactic boonies we are. But if we are able to detect candidate planets at such a rapid rate, it’s not inconceivable that with one civilization doing an Active SETI while the other is listening, that we might be able to hear each other. Maybe.

  3. jamessweet says

    Scratch that. I missed that it was a thousand light years away. I think in my mind I get it twisted up with the other recent Kepler discovery that was 30 light years away. If we were discovering boatloads of potentially life-hospitable planets within a 50 light year radius, then I could see contact happening. If there’s only a handful in that radius, though, maybe not. Who cares how many are a thousand light years away?

    Bah, ah well. So we remain alone.

  4. StevoR says

    @ ^ jamessweet :

    I get it twisted up with the other recent Kepler discovery that was 30 light years away.

    Which one was the 30 ly away one please?

    Kepler 22b – the planet in the habitable zone and which is, sadly, probably more a gas dwarf than a rock giant, more mini-Neptune than superMercury or SuperVenus – was about 600 light yeras away if I recall right.

    Who cares how many are a thousand light years away?

    Well, me just for one. Knowing how many are out there even thousands of light-years distant is intrinsically interesting and gives us some improved understandings of how common or otherwise planets are. Its less exciting than nearer extrasolar planetary finds perhaps – but still of *some* interest.

    So we remain alone.

    That we know of – for now. Or are we?

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