An international team of astronomers has announced the discovery of a new dwarf planet in our Solar System, finding a distant object beyond Neptune that circles the Sun in a spectacularly wide orbit.

Dubbed 2015 RR245 by the International Astronomical Union while they come up with a better name, the dwarf planet is about 700 kilometres in diameter, and its elongated orbit sends it out some 120 times further from the Sun than Earth. So it's a pretty distant neighbour.

Astronomers are finding more of these dwarf planets in the Kuiper belt all the time, but even so RR245 stands out for its size and orbit. In fact, the scientists who found it – as part of the Outer Solar System Origins Survey (OSSOS) – say it's the largest OSSOS discovery to date, of more than 500 trans-Neptunian objects identified by the Survey.

"The icy worlds beyond Neptune trace how the giant planets formed and then moved out from the Sun. They let us piece together the history of our Solar System," said researcher Michele Bannister from the University of Victoria in British Columbia, Canada. "But almost all of these icy worlds are painfully small and faint: it's really exciting to find one that's large and bright enough that we can study it in detail."

RR245's huge orbit – which you can see in the image above – takes it about 700 years to circle the Sun, and the researchers say it's currently travelling in for its closest approach, which will see it get within 5 billion kilometres of the Sun sometime around 2096.

That's after spending hundreds of years at more than 12 billion kilometres from the Sun, although the team acknowledges there's still a lot to be confirmed about RR245's precise movements, as we've only been able to observe just a tiny fraction of its epic loop so far.