Our Early Solar System May Have Been Home To a Fifth Giant Planet

sciencehabit writes: A cluster of icy bodies in the same region as Pluto could be proof that our early solar system was home to a fifth giant planet, according to new research (abstract). That planet may have 'bumped' Neptune during its migration away from the sun 4 billion years ago, causing the ice giant to jump into its current orbit and scattering a cluster of its satellites into the Kuiper belt in the outer solar system.

Comments

It makes you wonder what's out there.

[Rei]

Because things have been messing with bodies way far away from the sun. Take Sedna, for example. It's perihelion is 76 AU (Neptune's is about 31 AU from the sun, much to far to have an significant effect on Sedna). Sedna's apohelion is 936 AU. Very, very elliptical, and off-axis too - it clearly didn't form in this orbit from the sun's accretion disk, something has seriously messed with its orbit. But that couldn't have been something *close* to the sun, because then Sedna's orbit would have to come back close to it, aka, into the inner solar system. And Sedna is no little rock, it's 1000 kilometers in diameter - bigger than Ceres. For something to have thrown it into such an extreme orbit it had to be quite large, and not anywhere near where the large planets of our solar system are.

So the question is.... what?

It may seem an obvious assumption to think that if there were any more large planets in our solar system we'd have seen them - but it's actually not the case. By the data from WISE, we can rule out Jupiter-sized planets 26000 AU out, and Saturn-sized planets 10000 AU out. But there could still be multiple Earth-sized planets at only several hundred AU out - we really have no idea. It's just really hard to see things out there, the light they reflect from the sun is so weak.

Another possibility is that stars have sometimes drifted by our stellar neighborhood close enough to play havoc with things. Potentially more interesting is the concept that far more common than stars roaming past our neighborhood, there could be roaming planets outnumbering star that occasionally pass through and disrupt or are even captured by our system.

Re:It makes you wonder what's out there.

[Rei]

First of, "my theory"? No, I'm just repeating the current state of hypotheses on Sedna.

No, no research to date has ever ruled out earth-sized bodies more than a couple hundred AU, or Mars-sized bodies even closer. WISE ruled out Jupiter and Saturn-sized bodies for a good distance, but simply did not have the resolving power to find or rule out smaller bodies.

Every possibility I described is a "3 body slingshot". The issue is that at least one body has to be far out in order to have the object being "slingshotted" to have both a high apohelion and perihelion.

"research grant welfare criminal"? Okaaaaay........