Charon & Pluto
Pluto (right) and its moon Charon are the farthest planetary objects to have been visited by a human probeNasa/Reuters

Astronomers have identified a new dwarf planet in the far reaches of our solar system. The object, called V774104 for now, is a rocky world between 500 and 1000km (300 and 600 miles) in diameter, making it less than half the size of Pluto.

It is about 103 astronomical units away from the sun (around 15.5 billion km), making it the most distant dwarf planet ever spotted in our solar system. To put that in perspective, Pluto -- the farthest ever planetary object visited by a human probe -- is around 5.9 billion km from the sun.

Only two other objects have been spotted orbiting beyond the major planets in this region in space. They are known as the inner Oort cloud -- Sedna and 2012 VP113. However, astronomers believe there are several such objects awaiting discovery in the remote reaches of our solar system.

V774104 was spotted by the Subaru Telescope in Hawaii.

Mysterious origin

"We don't know anything about its orbit," Scott Sheppard of the Carnegie Institute of Washington, who announced the finding at the annual meeting of the American Astronomical Society's Division for Planetary Sciences in National Harbor, Maryland, told New Scientist.

"We just know it's the most distant object known."

Sedna
An artist's impression of the icy dwarf planet SednaNasa/Reuters

Scientists are still unsure of the origin and eccentric orbits of dwarf planets such as 2012 VP113 and Sedna, as the vast distance of these objects from the sun makes them difficult to study. One explanation is that their orbits were unsettled by a planet that was ejected from the inner Solar System billions of years ago. "Something might be shepherding the objects," Sheppard said.

Another possibility is that these objects were "stolen" by the sun from a nearby star around the time of its formation.

"Sedna and VP113 are the only objects in the known Solar System whose orbits cannot be explained by things in the known Solar System," Michael Brown of the California Institute of Technology told New Scientist.

"You don't know whether [V774104] is just a gee-whiz record holder or something super cool. I've got my fingers crossed for super cool," Brown added.