SPACE NEWS
August 11, 2005
A New Planet?
Scientists may have discovered the solar system's tenth planet
 An artist's drawing of 2003 UB313. |
Is an icy rock orbiting on the edge of our solar system actually a planet? Astronomers believe they’ve found the tenth planet. It is located 9 billion miles from the sun.
 |  Nighttime view of the Samuel Oschin Telescope at the Palomar Observatory. |
Discovering 2003 UB313
The rock was discovered in the Kuiper Belt, which is a group of rocks and asteroids at the border of our solar system. Astronomers at the California Institute of Technology Palomar Observatory first photographed the rock in October 2003.
Astronomers are calling the possible planet 2003 UB313. The mix of letters and numbers is a temporary name until scientists come up with a permanent one. Scientists believe 2003 UB313 is larger than Pluto and further away than Pluto. It's the biggest solar system discovery since Neptune and its moon, Triton, were discovered in 1846.
Mike Brown, a scientist who studies planets, said 2003 UB313 was not discovered sooner because it was found in a surprising location. “All of the planets are in a disc around the sun, and this object is 45 degrees out of that disc,” Brown said.
Is it Really a Planet?
Some astronomers say 2003 UB313 should not be considered a planet. They say it is much too different from the other planets in our solar system. They believe it should be classified as an object in the Kuiper Belt.
Brown, who works at the California Institute of Technology, does not agree. “If Pluto is a planet, it seems reasonable that something that’s bigger than Pluto, and further away than Pluto, should be called a planet, too,” he said. Brown made the discovery with scientists Chad Trujillo of the Gemini Observatory and David Rabinowitz of Yale University.
The International Astronomical Union (IAU) is the organization that determines what makes a planet a planet. If the IAU decides that 2003 UB313 is a planet, many more orbiting rocks will be classified as planets as well. It could take the IAU years to decide if 2003 UB313 is indeed a planet.
