You can see a movie of the tenth planet showing its motion on the sky in 3.5 hours, created by Gianluca Masi at http://www.bellatrixobservatory.org/2003ub313.gif

The tenth planet is the farthest-known object in the solar system at about 9 billion miles away from the sun, and the third brightest of the Kuiper belt objects. Neptune probably flung it into its highly inclined (44°) orbit. It’s currently glowing at magnitude 18.9 in the constellation Cetus.

Like Pluto, the tenth planet’s surface is believed to be predominantly methane ice. More data may be presented in September by the US team. Methane ice is unusual and suggests a primitive surface that has never been warmed much since the formation of the solar system.

The new planet is believed to be part of the Kuiper Belt, a large ring of icy objects that orbit beyond Neptune and are believed to be remnants of the material that formed the solar system. Objects in the Kuiper Belt are believed to have had a close encounter with Neptune, which then scattered them with its gravitational force into eccentric orbits. Pluto is also in the Kuiper Belt.

The tenth planet is approximately 87 astronomical units from the sun. An astronomical unit is the distance between the Earth and the sun.

The tenth planet is about 930 miles (1,500 kilometers) across, according to Mike Brown, an astronomer at the California Institute of Technology, who led the U.S-based team who announced the discovery of the planet.

The tenth planet, 2003-UB313, will be visible over the next six months and is currently almost directly overhead in the early-morning eastern sky, in the Cetus constellation.

It lies nine billion miles from earth so you would need a very powerful telescope to view it, such as the 48-inch Samuel Oschin Telescope at Palomar Observatory.

The new 10th planet is tentatively being called 2003-UB313. The object was originally discovered in 2003, but its status as a planet was only determined this year. As astronomers detected that it was rotating around the sun, they realized that they had discovered a previously unknown planet.

According to Mike Brown, a planetary scientist at the California Institute of Technology, “The new object is covered in methane ice and lies nine billion miles from earth and it’s the farthest object ever discovered to orbit around the sun. I’d say it’s probably one and a half times the size of pluto.”

Astronomers have proposed a name for the planet to the science’s governing body, the International Astronomical Union, and are awaiting the decision before announcing it. Once the name is announced, we will be sure to announce it here.

In the outer regions of our solar system, an object bigger than Pluto has been discovered and has now been designated as our tenth planet! This site, www.tenthplanet.info will chronicle the discovery of this planet, and will hopefully serve as a learning resource for future generations to come.