by Ann » Wed Aug 25, 2010 5:27 am
Very interesting for a number of reasons.
One reason is that this discovery brings home that we still know so little about other planetary systems. This is because it is so incredibly difficult to detect small, dark, light-weight planets as they cosy up right next to brilliant stars. Available techniques are being pushed to the limit to find more planets, and small rocky planets like the Earth are much, much harder to detect than planets the size and mass of Jupiter or even Neptune.
Another important point that is being emphasized by this discovery is that small rocky planets are not rare. We have no reason at all to think that rocky planets are hard to form. They are difficult to detect, but undoubtedly they exist in incredible numbers out there.
A third, very important point that needs to be made is that just because a planet is "Earth-sized" it isn't automatically "Earth-like". In fact, this discovery brings home once again that our Solar system is not "typical". The distance of the planets from our G-type Sun, their spacing and almost circular orbits here have so far not been matched by any other solar system that astronomers have detected. The solar system that is being described in today's APOD is different from our own in that the planets are lined up much closer to their sun than in our own solar system. As far as I can understand, there is no planet in this other solar system where water could be liquid, unless, of course, one of the Neptune-like planets which orbit at a more suitable distance from its sun has a moon with an atmosphere.
My conclusion is that there are myriads of solar system out there and huge numbers of planets, Earth-sized and otherwise, but for all of that the Goldilocks kind of planet where all the conditions for life are "just right" might nevertheless be exceedingly rare.
Ann
Very interesting for a number of reasons.
One reason is that this discovery brings home that we still know so little about other planetary systems. This is because it is so incredibly difficult to detect small, dark, light-weight planets as they cosy up right next to brilliant stars. Available techniques are being pushed to the limit to find more planets, and small rocky planets like the Earth are much, much harder to detect than planets the size and mass of Jupiter or even Neptune.
Another important point that is being emphasized by this discovery is that small rocky planets are not rare. We have no reason at all to think that rocky planets are hard to form. They are difficult to detect, but undoubtedly they exist in incredible numbers out there.
A third, very important point that needs to be made is that just because a planet is "Earth-sized" it isn't automatically "Earth-like". In fact, this discovery brings home once again that our Solar system is not "typical". The distance of the planets from our G-type Sun, their spacing and almost circular orbits here have so far not been matched by any other solar system that astronomers have detected. The solar system that is being described in today's APOD is different from our own in that the planets are lined up much closer to their sun than in our own solar system. As far as I can understand, there is no planet in this other solar system where water could be liquid, unless, of course, one of the Neptune-like planets which orbit at a more suitable distance from its sun has a moon with an atmosphere.
My conclusion is that there are myriads of solar system out there and huge numbers of planets, Earth-sized and otherwise, but for all of that the Goldilocks kind of planet where all the conditions for life are "just right" might nevertheless be exceedingly rare.
Ann