New dwarf planet discovered

The object could point towards another distant planet


The orbit of 2012 VP113 is shown in red, alongside Sedna in orange and the gas giants in purple.

Credit: Scott S. Sheppard/Carnegie Institution for Science

The Solar System has a new member after a new dwarf planet was found in its outer reaches, billions of kilometres from the Sun. It’s hoped that discovery of the object, named 2012 VP113, means there are many more of these small bodies – and perhaps even another Earth-sized planet in this far off region.

The dwarf planet is much smaller – at around 500km its diameter is less than Pluto's – and it is currently 12 billion km from the Sun on an orbit whose path takes 4,000 years to complete.

The lump of rock and ice was first observed in 2012 using the new Dark Energy Camera on the 4m Victor M Blanco telescope at Cerro Tololo Inter-American Observatory in Chile.

2012 VP113 is thought to be one of many similar objects in a place known as the inner Oort cloud. The region was predicted in 1950 to explain where many of the comets in the Solar System came from, but it is so distant that the bodies within it are near impossible to observe.

It took until 2003 to find the first one – the dwarf planet Sedna. The discovery of the new object raises the possibility that many thousands more such planetoids exist in the region.

What really has astronomers excited though is the possibility that another, much larger, planet that could exist even further out.  This is one of the explanations being suggested for the very elliptical – rather than circular – orbit of 2012 VP113.

An unseen planet, with a mass 10 times that of the Earth, could be lurking much farther out pulling the orbits of these smaller objects out of shape.

Another explanation for its eccentric orbit could be that in the distant past another star passed close by, distorting it.

"Some of these inner Oort cloud objects could rival the size of Mars or Earth,” reveals Scott Sheppard, from the Carnegie Institute of Science, one of the scientists who made the discovery. “It's probable that there could be a very large object out there.”

"We used to think there's just not much out there,” says Chad Trujillo, Sheppard’s colleague from the Gemini Observatory. “But it turns out there are some really interesting things.”

Researchers will continue to study and look for these very distant bodies. No one is sure how the objects in the Oort cloud formed, or how they came to be in their current location. Understanding more about them will help us to learn more about how the Solar System formed over four billion years ago.

Read about the Cerro Tololo Observatory in the March 2014 issue of BBC Sky at Night Magazine or learn more about the major planets in our Ultimate Guide To The Solar System.


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