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Really really lonely planets discovered by astronomers

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lone-planetLONELY planets roaming alone through the universe not bound to any central star have been discovered by an international team of scientists.


The lone worlds are about the size of Jupiter and astronomers believe they were probably were ejected from developing planetary systems.

And there are hundreds of billions of them in our Milky Way galaxy alone.

The discovery is based on a joint Japan-New Zealand survey that scanned the centre of the Milky Way during 2006 and 2007, revealing evidence for up to 10 free-floating planets.

The isolated orbs, also known as orphan planets, are difficult to spot, and had gone undetected until now. The planets are located at an average approximate distance of 10,000 to 20,000 light years from Earth.

"Although free-floating planets have been predicted, they finally have been detected, holding major implications for planetary formation and evolution models," said Mario Perez, exoplanet program scientist at NASA Headquarters in Washington.

The study, led by Takahiro Sumi from Osaka University in Japan, appears in the May 19 issue of the journal Nature.

The survey is not sensitive to planets smaller than Jupiter and Saturn, but theories suggest lower-mass planets like Earth should be ejected from their stars more often. As a result, they are thought to be more common than free-floating Jupiters.

Previous observations spotted a handful of free-floating planet-like objects within star-forming clusters, with masses three times that of Jupiter. But scientists suspect the gaseous bodies form more like stars than planets. These small, dim orbs, called brown dwarfs, grow from collapsing balls of gas and dust, but lack the mass to ignite their nuclear fuel and shine with starlight. It is thought the smallest brown dwarfs are approximately the size of large planets.

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