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9th Planet May Lurk in the Outer Solar System

The astronomer who helped kick Pluto out of the planet club believes a much larger body may be lurking in the outskirts of the solar system.

The astronomer who helped kick Pluto out of the planet club believes a much larger body may be lurking in the outskirts of the solar system.

If it exists, the solar system's ninth planet is estimated to be a gas world about 10 times bigger than Earth, California Institute of Technology (Caltech) astronomer Mike Brown wrote in this week's Astronomical Journal.

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Brown and colleague Konstantin Batygin, also at Caltech, used mathematical models and computer simulations to deduce the planet's existence, but they also have some observational evidence to support their claim. Several small icy bodies in the Kuiper Belt region beyond Neptune have quirks in their orbits that may be explained by the gravitational influence of a larger, more distant planetary cousin.

Scientists then realized that six of those bodies follow elliptical paths pointing toward the same direction in space.

"It's almost like having six hands on a clock all moving at different rates, and when you happen to look up, they're all in exactly the same place," Brown said in a press release, adding that the odds of that happening are about one-in-100.

The orbits also are tilted in the same direction, roughly 30 degrees downward relative to the orbital plane of the solar system's other eight planets.

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"We thought something else must be shaping these orbits," Brown said.

After checking if a batch of other Kuiper Belt objects might be responsible, the scientists started doing computer simulations that included a distant outer planet in various orbits.

They found an unusual match: a massive planet in an anti-aligned orbit, which is an orbit in which the planet's closest approach to the sun is 180 degrees across from the closest approach of the objects and known planets in the solar system.

"I was very skeptical," Batygin said in the release. "I had never seen anything like this in celestial mechanics."

Besides accounting for peculiarities in some Kuiper Belt objects' orbits, the predicted rogue planet, located at least 200 times farther away from the sun than Earth, also would pin other Kuiper Belt bodies into orbits perpendicular to the plane of the rest of the planets.

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"I realized there are objects like that," Brown said. "We plotted up the positions of those objects and their orbits, and they matched the simulations exactly."

"When we found that, my jaw sort of hit the floor," he added.

Planet Nine, as the mystery object is known, has not yet been observed directly, but it may have been captured during previous surveys.

"We hope that other people are going to get inspired and start searching," Brown said.

This artistic rendering shows the distant view from Planet Nine back towards the sun. The planet is thought to be gaseous, similar to Uranus and Neptune. Hypothetical lightning lights up the night side.

March 13, 2013, marks 20 years since the W. M. Keck Observatory began taking observations of the cosmos. Located in arguably one of the most extreme and beautiful places on the planet -- atop Mauna Kea, Hawai'i, 13,803 ft (4,207 m) above sea level -- the twin Keck domes have observed everything from asteroids, planets, exoplanets to dying stars, distant galaxies and nebulae. Seen in this photograph, the Keck I and Keck II telescopes dazzle the skies with their adaptive optics lasers -- a system that helps cancel out the turbulence of the Earth's atmosphere, bringing science some of the clearest views attainable by a ground-based observatory.

To celebrate the last two decades of incredible science, Discovery News has assembled some of the most impressive imagery to come from Keck.

Starting very close to home, the Keck II captured this infrared image of asteroid 2005 YU55 as it flew past Earth on Nov. 8, 2011.

Deeper into the solar system, the Keck NIRC2 near-infrared camera captured this beautiful observation of the oddball Uranus on July 11-12, 2004. The planet's north pole is at 4 o'clock.

This is a mosaic false-color image of thermal heat emission from Saturn and its rings on Feb. 4, 2004, captured by the Keck I telescope at 17.65 micron wavelengths.

A nice image of Saturn with Keck I telescope with the near infrared camera (NIRC) on Nov. 6, 1998. This is a composite of images taken in Z and J bands (1.05 and 1.3 microns), with the color scaling adjusted so it looks like Saturn is supposed to look to the naked eye.

This is Saturn's giant moon Titan -- a composite of three infrared bands captured by the Near Infrared Camera-2 on the 10-meter Keck II telescope. It was taken by astronomer Antonin Bouchez on June 7, 2011.

Another multicolored look at Titan -- a near-infrared color composite image taken with the Keck II adaptive optics system. Titan's surface appears red, while haze layers at progressively higher altitudes in the atmosphere appear green and blue.

This image of Neptune and its largest Tritan was captured by Caltech astronomer Mike Brown in September 2011. It shows the wind-whipped clouds, thought to exceed 1,200 miles per hour along the equator.

A color composite image of Jupiter in the near infrared and its moon Io. The callout at right shows a closeup of the two red spots through a filter which looks deep in the cloud layer to see thermal radiation.

HR 8799: Three exoplanets orbiting a young star 140 light years away are captured using Keck Observatory's near-infrared adaptive optics. This was the first direct observation by a ground-based observatory of worlds orbiting another star (2008).

Now to the extremes -- an image of Stephan's Quintet, a small compact group of galaxies.

The Egg Nebula: This Protoplanetary nebula is reflecting light from a dying star that is shedding its outer layers in the final stages of its life.

This is WR 104, a dying star. Known as a Wolf Rayet star, this massive stellar object will end its life in the most dramatic way -- possibly as a gamma-ray burst. The spiral is caused by gases blasting from the star as it orbits with another massive star.

Narrow-field image of the center of the Milky Way. The arrow marks the location of radio source Sge A*, a supermassive black hole at the center of our galaxy.

A high resolution mid-infrared picture taken of the center of our Milky Way reveals details about dust swirling into the black hole that dominates the region.

A false-color image of a spiral galaxy in the constellation Camelopardalis.

A scintillating square-shaped nebula nestled in the vast sea of stars. Combining infrared data from the Hale Telescope at Palomar Observatory and the Keck II telescope, researchers characterized the remarkably symmetrical “Red Square” nebula.

Galaxy cluster Abell 2218 is acting as a powerful lens, magnifying all galaxies lying behind the cluster's core. The lensed galaxies are all stretched along the shear direction, and some of them are multiply imaged.

The central starburst region of the dwarf galaxy IC 10. In this composite color image, near infrared images obtained with the Keck II telescope have been combined with visible-light images taken with NASA’s Hubble Space Telescope.

Keck I (right) and Keck II (left) domes at Mauna Kea.

Keck I and Keck II aim their adaptive optics lasers at the galactic center.