New Planet Discovered in Our Solar System

The discovery of a tenth planet orbiting our Sun was announced today by Dr. Michael E. Brown of the California Institute of Technology in Pasadena, California, USA. The planet is at least the size of Pluto and perhaps twice as large. It has been designated 2003UB313 for now while the name suggested by its discoverers is reviewed by the International Astronomical Union.

The announcement came just hours after news of another object discovered in the outer solar system hit the media. That object, designated 2003 EL61, is slightly smaller than Pluto in size and has a tiny moon. The team that discovered the tenth planet had also been actively observing 2003 EL61 but was scooped by astronomers from the Sierra Nevada Observatory in Spain.

Both objects were originally observed in 2003 but new analysis with updated observations has allowed astronomers to confirm the discoveries. Such distant objects move very slowly against background stars and require sequential observations over long durations to pin down their orbits. Estimates for their size are based on brightness. If Planet 2003UB313 reflected all sunlight it would be the size of Pluto, which is 2,300 kilometers (1,429 miles) across. Because most objects do not reflect all sunlight that hits them, the object must be larger than Pluto.

The newly discovered objects, like Pluto, are all members of the Kuiper belt, a band of objects orbiting the sun past Neptune. These remnants from the formation of the solar system are not well understood. NASA’s New Horizons mission to Pluto and its moon Charon will provide the first opportunity to view Kuiper belt objects up close. The spacecraft is expected to be launched January 11, 2005 and will travel for nearly ten years before flying by Pluto. If successful, the spacecraft may be targeted toward other Kuiper belt objects.

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Richard Leis

Richard Leis is a fiction writer and poet, with his first published poem forthcoming later in 2017 from Impossible Archetype. His essays about fairy tales and technology have been published on Tiny Donkey. Richard is also the Downlink Lead for the High Resolution Imaging Science Experiment (HiRISE) team at the University of Arizona. He monitors images of the Martian surface taken by the HiRISE camera located on board the Mars Reconnaissance Orbiter in orbit around Mars and helps ensure they process successfully and are validated for quick release to the science community and public. Once upon a time, Richard wrote and edited the science and technology news and commentary website Frontier Channel, hosted the RADIO Frontier Channel podcast, and organized transhumanist clubs. Follow Richard on his website (, on Goodreads (richardleis), his (@richardleis), Twitter (@richardleisjr), and Facebook (richardleisjr).