http://www.badastronomy.com/bablog/2008/03...e-solar-system/



Could there be another planet lurking in the dark, frigid outskirts of the solar system?

This isn’t as silly as it seems at first. No, I’m not talking Nibiru or any of that other nonsense (and it is nonsense), I’m talking about an actual planet, Earth-sized or so, that could be orbiting the Sun well beyond Pluto Neptune.

Why would we think there might be one out there?

We see some stars in the midst of forming planets. The stars are surrounded by thick disks of material, and in some we can actually see gaps in the disk, dark rings like the gaps in Saturn’s rings, that we think are due to forming planets gobbling up material in the ring. You’d think the disk would fade away with distance form the star, like our air gets thinner with altitude. But some disks appear to have sharp outer edges. This can be caused by a planet orbiting outside the disk; its gravity sweeps up the material and over time cleans up everything farther out. In one disk, this sharp boundary indicates a planet 200 AU out (an AU is the distance of the Earth to the Sun, about 150 million kilometers or 93 million miles).

Neptune orbits at 30 AU from the Sun, so 200 AU is a long way out. Could a planet like that have formed in our solar system? Maybe. Thing is, while our proto-planetary disk has been gone for billions of years, we do have lots of objects out past Neptune: the Trans-Neptunian Objects (they have lots of names, including Kuiper Belt Objects). These are basically giant balls of ice, some hundreds of miles across. As a group they form a puffy disk of objects stretching from Neptune’s orbit outward… but they seem to abruptly stop past about 50 AU out from the Sun. That’s called the Kuiper Cliff, the cause of which is unknown. Incidentally, it’s not because they’re too faint to see (that is, they’re there but we can’t spot them); at that distance we should have spotted lots of them by now.

Not only that, but a lot of these objects have orbits that are tilted more and are more elliptical than you’d expect if they just formed a long time ago and were left alone. Theyir orbits don’t bring them in very close — they tend to stay outside of Neptune’s orbit — but again, this is something that needs to be explained.

Could it be that there is another massive planet orbiting the Sun, way out there, which has swept up the objects gravitationally, creating the Kuiper Cliff and tossing the iceballs into tilted, oval orbits?

A newly released paper shows that may very well be the case. A team of scientists ran a whole mess of simulations, and found that a small planet (in this case, around half the size of the Earth) could have formed inside Neptune’s orbit (where there was plenty of material in the early solar system), gotten tossed into a bigger orbit by Neptune, and then knocked around the orbits of the iceballs, distorting their orbits and creating the Kuiper Cliff.

This idea is not new, but this new research is a provocative indicator of such a planet’s likelihood of existence. I’m not saying it’s out there, but it’s worth looking for. In fact, I’ve been saying that since about 1998 or so, when I worked on Hubble and was involved with a project that found a truncated disk around another star. I even worked with another astronomer on the team to investigate whether the robotic telescopes used to look for Near Earth Asteroids could spot such a planet.

It’s not all that easy. It wouldn’t be too faint to see, necessarily, but it’s a big sky. At that distance, the planet would move slowly, and the orbital motion would be hard to distinguish given the procedures used by NEA searches. We tried to convince some of them to modify their software to look for Planet X (yes, why not, though now it would be Planet IX), but we were met with mixed success. The fact that no one has discovered this planet shows you that this is still hard to do.

But maybe, just maybe, with this new research we’ll get people looking more seriously. It’s amazing to me that we can understand so much about galaxies and hugely distant objects, but find that there may be surprises waiting for us in our own back yard.

lol Remember I was the one who posted the link to that website. Science has wondered about the possibility of other planets for a long long time. I have never had a problem with that, Just Niburu on a collision course with Earth.



I wouldn't be surprised to find other planets and moons out there orbiting the Sun. If they keep finding them we will have to extent the rhym!!

My, Very, Ernest, Mother, Just, Sits, Up, Near, Pop....Well Pluto isnt a planet any more so I geuss she just sits up near.....

Nice Find Cricket

Dundee,, I never said planet x was going to HIT the earth, just pass by it. And I am sorry I put this in, I didnt realize it was the same link. soory

The bad astronomy poster maybe talking about an “… actual planet, Earth-sized or so,…” however the article he was referring to describes the hypothesized planet to be “ 30 to 70 percent” the size of Earth and the article does not mention this hypothetical planet x coming near the Earth… ~rore

Japanese scientists eye new planet
Feb 27, 2008
TOKYO (AFP) — Scientists at a Japanese university said Thursday they believed another planet up to two-thirds the size of the Earth was orbiting in the far reaches of the solar system.
The researchers at Kobe University in western Japan said calculations using computer simulations led them to conclude it was only a matter of time before the mysterious "Planet X" was found.
"Because of the very cold temperature, its surface would be covered with ice, icy ammonia and methane," Kobe University professor Tadashi Mukai, the lead researcher, told AFP.
The study by Mukai and researcher Patryk Lykawka will be published in the April issue of the US-based Astronomical Journal.
"The possibility is high that a yet unknown, planet-class celestial body, measuring 30 percent to 70 percent of the Earth's mass, exists in the outer edges of the solar system," said a summary of the research released by Kobe University.
"If research is conducted on a wide scale, the planet is likely to be discovered in less than 10 years," it said.
Planet X -- so called by scientists as it is yet unfound -- would have an oblong elliptical solar orbit and circle the sun every thousand years, the team said, estimating its radius was 15 to 26 billion kilometres.
The study comes two years after school textbooks had to be rewritten when Pluto was booted out of the list of planets.
Pluto was discovered by the American astronomer Clyde Tombaugh in 1930 in the so-called Kuiper belt, a chain of icy debris in the outer reaches of the solar system.
In 2006, nearly a decade after Tombaugh's death, the International Astronomical Union ruled the celestial body was merely a dwarf planet in the cluttered Kuiper belt.
The astronomers said Pluto's oblong orbit overlapped with that of Neptune, excluding it from being a planet. It defined the solar system as consisting solely of the classical set of Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune.
The team noted that more than 1,100 celestial bodies have been found in the outer reaches of the solar system since the mid-1990s.
"But it would be the first time to discover a celestial body of this size, which is much larger than Pluto," Mukai said.
The researchers set up a theoretical model looking at how the remote area of the solar system would have evolved over the past four billion years.
"In coming up with an explanation for the celestial bodies, we thought it would be most natural to assume the existence of a yet unknown planet," Mukai said.
"Based on our hypothesis, we calculated how debris moved over the past four billion years. The result matched the actual movement of the celestial bodies we can observe now," he said.
He was hopeful about research by Kobe University, the University of Hawaii and Taiwan's National Central University.
"We are expecting that the ongoing joint celestial observation project will eventually discover Planet X," Mukai said.