Dwarf planet discovered at solar system's edge
Scientists have identified a new dwarf planet in the distant reaches of our solar system
10:29AM GMT 27 Mar 2014
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Astronomers have found a new dwarf planet far beyond the orbit of Pluto and can only guess how it got there.
The diminutive world, provisionally called "2012 VP 113" by the international Minor Planet Center, is estimated to be about 280 miles in diameter, less than half the size of a neighbouring dwarf planet named Sedna discovered a decade ago.
The discovery of the dwarf planet, far beyond Pluto, extends the known reaches of our solar system and provides clues to another new planet ten times the size of the Earth. Scientists believe it may have been hurled there when the solar system was born, according to scientists who say the finding may help them reconstruct the 4 billion-year-old event.
The dwarf planet, with a diameter is one-eighth that of the moon, was spotted by researchers beyond the Kuiper belt, a region of space formed by floating, icy chunks that lies past Neptune, still considered the furthest large planet from the sun.
Scientists once thought that the region was empty, a “no-man’s land,” according to Scott Sheppard, a researcher at the Carnegie Institution for Science in Washington and a study author. The discovery in 2003 of a dwarf planet scientists named Sedna started a hunt for other objects. The latest finding, published in the journal Nature, hints more may exist there.
"We've been using a large camera on a four-metre telescope in Chile, and it's a very powerful facility," said Mr Sheppard.
"Our survey covered just a very small area of the sky - about 220 full Moons of sky. So, there's a lot more sky out there, and we predict, based on this one object, that across the whole sky we could expect to find 900 objects of 1,000km or bigger in size.
"Some of these could be bigger than Pluto; some could even be bigger than Mars or the Earth. The problem is they're just so distant, especially when they're in the far parts of their orbits, that they're just too faint to detect," he told BBC News.
The new dwarf planet has been nicknamed “Biden” by its discoverers because its full name, 2012 VP113, is too much of a mouthful, Sheppard said. The rules of the International Astronomical Union prevent researchers from naming objects in space after politicians, so they are considering a name from Eskimo mythology because the planet is extremely cold, he said.
It has taken 10 years to find the latest dwarf planet because scientists need powerful telescopes to detect planets so far out. Sedna is 76 astronomical units from the sun, which means it’s 76 times the distance from the earth to the sun. VP113, which is smaller and dimmer, is even further out at 80 astronomical units.
Mr Sheppard and lead author Chad Trujillo, a researcher at the Gemini Observatory in Hilo, Hawaii, used a new camera installed in 2012 at the Cerro Tololo Inter-American Observatory in La Serena, Chile, to make their discovery.
They are now scanning the skies for more objects in the inner Oort cloud, the region behind the Kuiper belt, and hope to find 10 or more, Trujillo said. Then, the scientists plan to use their findings to reconstruct the birth of the solar system, based on the objects’ orbits and movements.
If scientists can determine how the two dwarf planets got there, “we can trace back our sun’s formation history,” Mr Sheppard said, adding: "They had to be tossed out there or brought out there.”
Current theories include a “rogue planet” being pushed out of the evolving solar system in its early days, pulling smaller pieces out with it, he said. Another theory proposes that a star passing close to our sun may have dragged the dwarf planets out into the inner Oort cloud.
