Can there be giant rocky planets??? (material is earth-like but size closer to Jupiter) I know about the close orbiting, Jupiter sized planets found ... but they claim they are gaseous. They may be .. but, could a rocky version possibly be discovered? I can't figure it out ... some astronomer friends say emphatically "no!" but can't explain why. do YOU know?? me.
I suppose the reason we haven't found one is because it's difficult to get that much rock in one place. Rock would probably form earth-sized planets and then due to orbital mechanics would not aquire enough to become that size. Remember, they also said that those "roasters" were impossible.
First of all, in our solar system at least, there simply isnt enough rocky material to form such a big planet. But of course there might be elsewhere. The next crunch is wether such a planet would be stable; as the material accretes (falls down) t ocreate the planet, it gets very hot, thats partly why the interiour of the Earth is hot. Inside such a supermassive planet the pressure would be very high indeed, possibly increasing nuclear reactions (another reason the interiour of Earth is hot), and this might blow the planet apart. Probably there is a critical mass there. Hans
Studying the spectra of parent stars along with the doppler shift shows a slight wobble in some stellar orbits - its thought that this is caused by the gravitational force of large planets - the limit on this minimum mass means the planetary size must be greater than or comparible with Jupiter, seeing as the Parent star Spectras have only one set of Spectral lines it is likely that the planets may be rocky - i think this arguement is ok. Inka x
If I remember correctly, there are many systems that have indicated that there are Jupiter size and larger planets that pull on its primary by the wobble that we have detected. I also seem to remember to Jupiter is suspected of having a rocky core and a layer of liquid or metalic hyrdogren around it. (Thanks (Q) for the link in gas giants) Jupiter has been picking up rocky masses for as long as it has been around. Were it not for Jupiter cleaning up the solar system, we would have had many more strikes by large mass asteroids and the like. I have always wondered why the inner planets are rocky and the outer planets gaseous. What caused the formation of the system to happen this way?
Wet1, I heard that the theory was that when the sun was formed solar wind blew the lighter materials into more distant orbits, leaving the heavier materials in the center. Pluto, the one outer planet that isn't gaseous, probably formed from the oort cloud.
While that makes sense at the start, you have to think a little about it. If solar radition is moving the unused debris out of the system then that leaves precious little time for the larger planets to get their mass before it is out of reach. This means if they didn't form up at the beginning and have nearly all their mass already then there won't be much to mop up at the end. So what happened to start this. Was the accreation disc like a giant centrifuge allowing the lighter stuff to move outward while the cloud was still there? This might account for the inner planets rocky nature. Somehow, I just don't see that happening in space. There was a theory put forward sometime last year (I remember reading it) that maybe our time scales are wrong on how long the larger planets took to form. It suggested that it could be far less time in forming than what we think. Put that with the above idea that the new fledgling star was starting to push the lighter elements out of the system by light pressure and we might have a scenerio...
Maybe the mysterious force that's tugging on the Pioneer spacecraft would hold things together, I believe that's what one of the mysteries of gravity is, and that's really what it all comes down to. Yeah...yeah now that I think about it the accretion disk sounds pretty logical, with the information availible to us at this point in history.
Traditionally, theories of giant planet formation have focused on explaining the growth of planets under the protoplanetary disk conditions expected at 5 AU, the current orbital radius of Jupiter. However, the large spread in the observed orbital radii of extra-solar planets may be an indication that giant planets actually form over a range of disk radii and physical conditions. Indeed, it is probably inaccurate to assume that planets formed where they are now observed to be because dynamical effects, such as orbital migration due to tidal interactions between the disk and protoplanet and dynamical scattering between planets following disk dissipation, are likely to significantly alter planetary systems. Dynamical studies indicate that these processes can alter the masses (via mergers), orbital radii, and eccentricities of planets, and reduce the number of surviving planets (via mergers and ejection). In the light of these recent developments, planet formation now appears to be a much more complex process than was originally envisioned. It may well be that the observed diversity of planetary systems is a manifestation of the multitude of physical processes at work, and the interactions between these processes, in the formation of planetary systems. Wetherill has suggested that the development of life on the Earth may be a consequence of the existence of Jupiter, because Jupiter probably cleared the inner solar system of planetesimals that would otherwise have impacted the Earth at a damagingly high rate. Thus, understanding the formation of giant planets is critical to understanding the origin of the Earth and our solar system. http://www.aura-nio.noao.edu/book/ch2/2_4.html
Is there a name for that theory? The one about how Jupiter made it possible for life on Earth to develop? I've heard about it since seventh grade but I don't believe they've ever stamped someone's name on it...
