Earth-Sized World Could Lurk in Outer Solar System

[MeteorWayne]

I posted this in the 2009 YE7 thread but think it derserves it's own. Alan Stern and Mike Brown on the same page!!

http://www.space.com/scienceastronomy/1 ... anets.html

Some astronomers say that a planet the size of Mars or Earth could be lurking on the fringes of our solar system. But even the latest space telescopes that launched in 2009 stand little chance of finding such a distant object.

Such a world, if it exists, would probably have an orbit far beyond Pluto or similar dwarf planets in the outer solar system. It would likely resemble a frozen version of Mars or Earth at best, a most unsuitable home for life. And it would not be alone.

"When the solar system's story is finally written, it's much more likely that it will have closer to 900 planets rather than the nine that we grew up with," said Alan Stern, a planetary scientist at the Southwest Research Institute (SwRI) in Boulder, Colo.

Just a handful of those potential discoveries might reach the size of Earth, compared to a swarm of Pluto-sized bodies that Stern and others expect to find.

Each object – be it termed a planet, dwarf planet or otherwise – would serve as a frozen time capsule that could reveal much about the early evolution of the solar system. It could even force scientists to once again rethink the definition of a planet, following the controversial downgrading of Pluto to a dwarf planet.

Beyond the belt

Pluto's downfall came in part because astronomers discovered a number of smaller planetary objects in the outer solar system. Dwarf planets such as Eris occupy a cluttered, icy region beyond Neptune known as the Kuiper Belt. But a planet the size of Mars or Earth has not turned up at such range.

"For the Kuiper Belt we can already say there is nothing Earth or Mars sized, as its dynamical effects would be easily seen," said Mike Brown, an astronomer at Caltech who led teams that discovered Eris (and nicknamed it "Xena" at first) and other dwarf planets.

One of Brown's past dwarf planet discoveries, Sedna, occupies a strange elliptical orbit between the Kuiper Belt and the more distant Oort Cloud — a possible sign of the gravitational influence of another world as big as Earth, one astronomer proposed. But Brown suspects that such a large object would have been spotted already.

Brown and Stern say that the Oort Cloud represents a more likely prospect for worlds the size of Mars or Earth. The Oort Cloud surrounds our solar system with billions of icy bodies at distances as far out as 50,000 times the distance between the sun and Earth.

"Once you go beyond the Kuiper Belt, to the Sedna region or the Oort Cloud, you can always hide things by putting them farther away," Brown told SPACE.com

 

[R1]

The new telscopes don't have a chance of finding any nearby planets??
Is that referring to the new, infrared, supercooled scope that was supposed to map the entire sky?

 

[yevaud]

They're not designed to resolve objects at such a close distance.

 

[bdewoody]

I've been wondering for quite a while how many planets left behind by their exploding parent star were cruising around the neighborhood. I understand that most rocky planets would be destroyed by their parent star when it explodes but it seems logical that some would retain their form while being flung into interstellar space.

 

[cyclonebuster]

How we know "Gods Good Earth" wasn't one of these objects many moons ago?

 

[Solifugae]

I wonder more about a possible cool brown dwarf/gas giant mentioned in the run up to the WISE launch, but an "Earth" would be cool too.

 

[abq_farside]

Planet X maybe? Or XI, XII, XIII,........

 

[CalliArcale]

How we know "Gods Good Earth" wasn't one of these objects many moons ago?

It's certainly possible, but not likely. Earth's orbit is pretty regular (not inclined to the Sun's equator, and nearly circular), which strongly suggests that it formed in this location. Captured objects, or objects whose orbits have changed a LOT, tend to have weird orbits.

 

[yevaud]

I've been wondering for quite a while how many planets left behind by their exploding parent star were cruising around the neighborhood. I understand that most rocky planets would be destroyed by their parent star when it explodes but it seems logical that some would retain their form while being flung into interstellar space.

Well, it's believed that they exist, and are referred to as "Free Planets" or "Rogue Planets." However, other than some intriguing evidence of captures (as Calli mentions), there has never been one imaged or seen. It's theory only. We can only infer that they exist, and captures occur.

 

[Fallingstar1971]

Well, I would think most rouge planets would be frozen, at least on the surface.

If a planet can be captured, it stands to reason that a planet could be flung out of a solar system.

And if it were frozen, then would it look like a super massive comet if it approached any star? Could such a world develop a "tail" as it approached said star?

That would be cool

Star

 

[yevaud]

Doubtful it'd develop a trail. Comets ablate in the solar wind; a planet is far too massive for that to occur.

They would tend to be very "dark" as well, meaning that unless a really chance accidental occlusion when a telescope was imaging something occurs, we'd never even see the thing. Only if it got into the solar system proper would we begin to "see" it's presence, due to perturbation of orbits, rocky and cometary material suddenly being perturbed inwards from the halo, etc. And once that close, we could indeed image it.

Certainly these can be ejected from a solar system. That's a classic three-body issue (or four or five, etc.), that of long-term stability of the additional body(s), which can be ejected from the system. Many three body situations are only quasi-stable, meaning that over the long term, the additional bodies can be perturbed right out of their orbits and go rogue.

Mind you, again, this is mostly theory.

The following relates to this: http://www.scholarpedia.org/article/Three_body_problem

 

[MeteorWayne]

Well, it's clear that if any icy objects like Pluto or Haueme were perterbed into the inner solar system (inside Jupiter's orbit, say) the ices on the surface would sublimate and a comet would be created. But once you get outside of Saturn's orbit, the intensity of solar radiation (that's what causes the coma, BTW, not the solar wind) is too low for much sublimation to occur.

Once the ices are sublimated, the gas ions create the blue tail of a comet and follow the magnetic field, and the dust released in the process is then blown by the solar wind creating the yellow comet tail. But the solar wind does not liberate the dust.

 

[Ogeon]

It's obvious that with the equipment we currently have deployed, direct visual observation of these possible planets it not possible. Perhaps a more indirect method could be used? One of the methods used to detect planets around distant stars is to measure the apparent brightness of that star and to note any changes in that brightness...indicating a possible planet crossing the path between us and it's parent star. Since we can't use our parent star in the same manner, what about using other stars and watching to see if any of them "wink out" - this could indicate a planet in the outer solar system. Think of watching the New Moon passing through the sky obscuring the stars behind it as it passes...we can't directly see the Moon, but we can note the stars that it hides. I know that there is a LOT of sky to cover and this may not be the most efficient means of locating possible planets in our outer solar system, but perhaps it could be a jumping off point for a better method.

 

[elroy_jetson]

There's a lot we don't know about Earth, let alone Sol system, the Milky Way galaxy, and beyond. The outer fringe of our solar system does indeed harbor wonders we can only begin to imagine, along with answers to questions that have been with us since the first sentient mind pondered the meaning of life. There will also be answers to questions we haven't even asked yet. Our telescopes can show us a great deal, but not enough. We need to develop the means to visit the far corners of our solar system, because knowledge is priceless. And there just might happen to be some valuable resources "out there" that could be exploited for the benefit of humanity.

 

[yevaud]

Once the ices are sublimated, the gas ions create the blue tail of a comet and follow the magnetic field, and the dust released in the process is then blown by the solar wind creating the yellow comet tail. But the solar wind does not liberate the dust.

Incorrect. Ablation is one of the mechanisms liberating volatiles from a Comet. This is a differential ablation due to inhomogenieties in the distribution and thickness of mantling dust accumulations.

Trust me on this; LPI will back this up.

 

[MeteorWayne]

Well, until we BOTH do more research, we'll have to disagree for the moment. My position is that the primary mechanism for release of volitiles, (and the dust contained within) is heating from solar radiation.

You are saying that the solar wind (the particle flow from the sun) is the primary mechanism? If so, I've never heard that before.

Ok, off to our collection of sources for support, my friend

Wayne

 

[yevaud]

*A* mechanism, not *the* mechanism.

http://adsabs.harvard.edu/full/1986LPI....17..512M

As you will see, the statement, "Dust mantles have a profound effect on the thermal history of cometary nuclei and therefore on the rate of volatile release by comets."

 

[MeteorWayne]

*A* mechanism, not *the* mechanism.

http://adsabs.harvard.edu/full/1986LPI....17..512M

As you will see, the statement, "Dust mantles have a profound effect on the thermal history of cometary nuclei and therefore on the rate of volatile release by comets."

I agree with that, but I saw nothing in the excerpt that indicated a mechanism related to the solar wind; in fact to my reading it showed an insulating effect from solar radiation by the mantle when it's thick enough. Maybe the full paper is more explicit. Note the word "thermal", which to me implies a radiational effect rather than one from the solar wind.

 

[yevaud]

The term "ablation" is pretty specific. To be ablated requires something to do the ablating, does it not?

For example, this was imaged during Shoemaker-Levy, "Just before reaching Jupiter, the Hubble Space Telescope took this view of some of the comet's fragments, enlarged enough to show cometary material ablating off in a direction away from the solar wind: " http://rst.gsfc.nasa.gov/Sect19/Sect19_23.html

The following backs this up, "The other class consists of comets which are relatively small "dirty ice balls" or a nucleus of ice and rock. As those with certain orbits approach the Sun, the solar wind and other forces cause them to ablate..." http://www.fas.org/irp/imint/docs/rst/S ... 19_22.html

 

[lowrieder]

My guess is that a large planet exists somewhere in the outer solar system beyond the orbit of pluto. Obviously we have planets like Sedna (and yes i said planet), but we may have even more. Actually the presnce of a large planet with an unusual orbit might explain how objects in the outer system break from their orbits and impact the earth.

 

[Astro_Robert]

There used to be a fairly informative website that I believe was run by someone affiliated in some way with the minor planet center. In it, there was a nice article for layman that discussed the possibilities of finding a "Planet 10" or any large object out beyond Pluto.

The closest I could find at the moment is Chad Trujillo's home Page: http://www.chadtrujillo.com/

The description of Sedna includes a blurb about this, but I will keep looking for a comparable link to the old one. Anyway, what the old blurb on Planet X indicated was that at sufficiently large distances even a Jupiter class planet could (not that it is, but could) lurk without purturbing Neptune. (Apparently the supposed Neptune perturbations that caused Tombaugh and others to look for Planet X, were really measurement errors). The article went on to calibrate things; if I recall correctly an Earth mass object could lurk at around 100 AU or so, and a Jupiter mass object could lurk at 300 AU or so. Its been a while so I may be a little off in my calibration, but you get the idea: The lack of perturbations in Neptune's orbit does not preclude Planet X, it just means that if any large bodies are out there, then they are really out there.

 

[yevaud]

Well, certainly canon on "Planet X," or whichever appelation you care to give it, is that it must be on a highly elliptical orbit that only occasionally brings it near the Oort Cloud, or it's efects on any other outer system body would be noticed. And, as you say, no such orbital anomalies have been determined.

 

[ClevelandSteamer]

Distant planets?? I can't even find my keys!

 

[Caley]

Someone mentioned detecting bodies in our outer solar system by the occultation method of stars. Didn't one of the newer dwarf planets get detected in that manner? It is certainly possible to find another in that manner, but I would think that it would take a significant amount of time and resources and lots of luck to find more. Maybe too much time for the professional astronomer to give up. Computers probably could be set up to detect differences in images, and a person check these to determine if it is actually an occultation, or just a glitch in an image.

 

[yevaud]

That's correct, it would take a significant amount of time. Obviously, the reason detecting exoplanets via occultation is do-able is that we have a visible and bright target - the exoplanet's primary. In the case of a Rogue Planet, with low albedo and no primary that it's orbiting in a predictable fashion, it is impossible to pick out of the dark. An occultation would be a chance encounter. Or, historical images over time could be re-analyzed to see if any such occultations occurred, but weren't noticed at the time.

With respect to the historical record, the various mass extinctions in the past (which may or may not have necessarily been due to an impact event) don't match up to any predictable and regular interval, which might be indirect evidence of a periodic body passing near. Regrettably, it isn't there, and so makes the case for "Planet X" weaker.

Here's the url for an extinction graph: http://users.tpg.com.au/users/tps-seti/crater_age_6.gif - it's too large for the post frame.