Researchers discovered a remarkable planet 25,000 light-years away that looks similar to our own solar system's Uranus.
This is the first time an "ice giant" (made of part gas and part ice) like Uranus and Neptune has been discovered outside of our solar system, The Ohio State University reported.
The planet is extremely far away, but is believed to orbit in a binary star system and has a similar orbital pattern to Uranus.
"Nobody knows for sure why Uranus and Neptune are located on the outskirts of our solar system, when our models suggest that they should have formed closer to the sun," said Andrew Gould, professor of astronomy at Ohio State. "One idea is that they did form much closer, but were jostled around by Jupiter and Saturn and knocked farther out."
"Maybe the existence of this Uranus-like planet is connected to interference from the second star," he continued. "Maybe you need some kind of jostling to make planets like Uranus and Neptune."
The binary system contains one star that is about two thirds as massive as our sun and one that is about one-sixth as massive. The planet is four times as massive as Uranus, but orbits the star at almost exactly the same distance.
The planet was discovered through a phenomenon called "gravitational microlensing," in which the gravity of a star focuses the light of a more distant one in a magnification process similar to a lens. In rare cases a planet can be spotted orbiting the lens star.
"Only microlensing can detect these cold ice giants that, like Uranus and Neptune, are far away from their host stars. This discovery demonstrates that microlensing is capable of discovering planets in very wide orbits," said Radek Poleski, postdoctoral researcher at Ohio State.
The findings were published in a recent edition of the Astrophysical Journal.
