WELLINGTON - Ten new "floating" planets, which drift through the galaxy rather than orbiting stars, have been discovered by an international team of astronomers led by New Zealand scientists.

The finding of the Jupiter-sized planets was announced Thursday by the international journal Nature as having "profound" implications and opening a new chapter in the history of the Milky Way.

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The orphan gas planets, formerly the stuff of science fiction, were discovered using software developed by Massey University computer scientist and astrophysicist Ian Bond, the Dominion Post newspaper reported.

"They're giant planets in our galaxy, around the size of Jupiter and somewhere between us and those distant background stars," he told the newspaper.

The planets are believed to be about two-thirds of the way to the centre of the galaxy, which is about 25,000 light years away.

If they were visible to the naked eye, the planets would be pitch black, as they emitted no light, Bond said.

The find raised the possibility that smaller, Earth-sized free-floating planets, which could support life, were yet to be detected.

Bond told the newspaper the orphan planets could have been ejected from a solar system because of close gravitational encounters with other planets or stars, or they could have grown from collapsing balls of gas and dust, but lacked the mass to ignite their nuclear fuel and produce their own starlight.

The discovery team included researchers from Massey, Auckland, Canterbury and Victoria universities, all based in New Zealand, as well as from Osaka University in Japan and the University of Notre Dame in Indiana, in the United States.

The group is part of the microlensing observations in astrophysics study, which uses a microlensing telescope at Mt John Observatory at Lake Tekapo, in the South Island of New Zealand.

Gravitational microlensing is an astronomical phenomenon that refers to the bending of light that occurs when a star is aligned with a massive object in front of it, allowing the study of planetary bodies that emit little or no light.