ISTR that Pluto was demoted because it doesn't dominate it's orbit gravitationally (ISTR the Hill sphere came into it).If this postulated object is "shepherding" Sedna and 2012 VP113, does that mean that it might fit within the definition of "planet" rather than "dwarf planet"?Cheers, Martin
Quote from: MP99 on 03/26/2014 06:34 pmISTR that Pluto was demoted because it doesn't dominate it's orbit gravitationally (ISTR the Hill sphere came into it).If this postulated object is "shepherding" Sedna and 2012 VP113, does that mean that it might fit within the definition of "planet" rather than "dwarf planet"?Cheers, MartinIt's possible. For its gravitational effect to be large enough to shepherd these bodies like this it would need to be much larger, possibly Earth size or bigger. I doubt a dwarf planet would have that extensive an influence.
Be funny if the textbooks had to be revised again back to nine planets.
Quote from: Star One on 03/26/2014 07:04 pmBe funny if the textbooks had to be revised again back to nine planets.Just name it "Pluto" and ignore the last fact we'd name a "dwarf" planet intead of the "right" one... Think of the cost savings by going back to older text books Randy
I remember when Sedna was discovered, and 10 years later we've found this new object that orbits even further out.
I keep seeing news reports referring to this as a "Dwarf planet". It's smaller than Vesta and doesn't seem likely to be spherical, so how is it a Dwarf?
Quote from: Bubbinski on 03/26/2014 07:04 pmI remember when Sedna was discovered, and 10 years later we've found this new object that orbits even further out. The Large Synoptic Survey Telescope (LSST) is under construction right now. You can Google it. When that becomes operational, you can expect the number of discoveries of these kinds of objects to increase quite a bit. As you can guess from the name, the point is that the LSST does a survey, meaning that it looks at a relatively wide bit of the sky. That's how you find small, faint moving objects. It is much harder to do with telescopes that have a very narrow field of view, because the object might be right outside of your field of view and you'll miss it.
The monsters are multiplying. Just months after astronomers announced hints of a giant "Planet X" lurking beyond Pluto, a team in Spain says there may actually be two supersized planets hiding in the outer reaches of our solar system.When potential dwarf planet 2012 VP113 was discovered in March, it joined a handful of unusual rocky objects known to reside beyond the orbit of Pluto. These small objects have curiously aligned orbits, which hints that an unseen planet even further out is influencing their behaviour. Scientists calculated that this world would be about 10 times the mass of Earth and would orbit at roughly 250 times Earth's distance from the sun.Now Carlos and Raul de la Fuente Marcos at the Complutense University of Madrid in Spain have taken another look at these distant bodies. As well as confirming their bizarre orbital alignment, the pair found additional puzzling patterns. Small groups of the objects have very similar orbital paths. Because they are not massive enough to be tugging on each other, the researchers think the objects are being "shepherded" by a larger object in a pattern known as orbital resonance.
There is also the possibility that, as seems to be happening in the Fomalhaut system right now, the orbital distances of several major planets could have changed several times before re-stabilising. This would allow for large objects to be thrown out of the middle solar system (as I think of the area between Jupiter and Neptune's orbits) out into the Kuiper Belt and beyond.
Actually, Planet IX, ever since that whole Pluto thing ...