Collective gravity, not Planet Nine, may explain the orbits of "detached objects"

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Just like other "detached objects", Sedna has a circular orbit that moves it away from the system's major planets, propelling it into a journey of more than 11,000 years around the sun.

There is something out there, beyond Neptune - it is large and dense, affecting the orbit of dwarf planets just outside the Solar System.

Scientists doubted the existence of Planet X. the Experts believe that beyond the orbit of Neptune celestial bodies the planet's gravity is not affected.

Some of these bodies - which are called trans-Neptunian objects (TNOs), notes - have very peculiar orbits that set them apart from everything else in the solar system.

Instead of being tugged on by a giant invisible planet, those Solar System objects could have jostled each other like bumper cars, which has knocked some of them into new orbits - so say researchers from the University of Colorado Boulder.

Researchers at California University Boulder (CU Boulder) presented a new theory about the existence of icy, minor planets almost eight billion miles from the sun. Using the simulations, they had calculated that the orbits of icy objects beyond Neptune circle the sun like the hands of a clock.

In the latest study, presented this week at a meeting of the American Astronomical Society, astronomers looked at new models depicting how the massive swarm of objects that make up the Kuiper Belt orbit the sun. Possible separate object is Sedna, the perihelion of which is two times beyond the orbit of the eighth planet.

Sedna's eccentric orbit has been cited as evidence that another, larger planet's gravity must be nudging it off-kilter somewhere along its path, and the mysterious Planet Nine is usually assumed to be responsible.

"While we're not able to say that this pattern killed the dinosaurs", Fleisig said, "it's tantalizing".

In some ways it's easier to imagine a grouping of large, rocky asteroids than it is to imagine a massive unseen planet, but it's far from a confirmation. Adding mass means that more of that material could have stuck around, their smaller size keeping them from being detected. Usually, the larger an object is, the easier it is to discover.

This theory matches a 2012 finding showing the larger a detached TNO becomes, the more distant its orbit gets from the Sun.

In addition, the presence of the small handful already spotted suggests a larger population, Madigan said.

Remarkably, these relatively insignificant objects may also be culpable in the extinction of the dinosaurs.

Previous studies have suggested that mass extinctions may occur with regularity, and some researchers have linked this perceived periodicity to pulses of comet or asteroid strikes. Other researchers have cited dark matter or the sun's hypothesized unseen companion star, Nemesis, as candidates. Only small detail: Planet Nine has never been observed.

"You see a pileup of the orbits of smaller objects to one side of the sun", said Fleisig, who is the lead author of the new research.

"It's exciting and suggestive", Madigan said.