The oldest known alien planet potentially able to support life has been discovered just near the Earth.

Then newly discovered planet called Kapteyn b is just 13-light years away from the Earth and is believed to be 11.5 billion years old. Scientists say it is 2.5 times older than our own planet and about 2 billion years younger than the universe, according to Space.com.

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In a statement, study lead author Guillem Anglada-Escude from the Queen Mary University of London said both Kapteyn b and its newly-found sister planet Kapteyn c revolve around a red dwarf called Kapteyn's Star. However, researchers said only Kapteyn b, which is five times as big as the Earth, is potentially habitable, as Kapteyn c is believed to be too cold to support life.

Anglada-Escude said their group did not expect to find a possibly habitable "super Earth" orbiting around Kapteyn's Star. The latter is one-third the size of the sun but can be seen through amateur telescopes because of its close proximity to our planet.

Kapteyn b is situated in the habitable zone of the star, wherein it could support liquid water. This planet completes its orbit after 48 days, while the bigger Kapteyn c is located farther from the star and completes its orbit every 121 days.

Researchers explained that Kapteyn's Star initially belonged to a dwarf galaxy that was later absorbed and disrupted by Milky Way. This threw Kapteyn and its planets into a fast and elliptical orbit in our galaxy's spiral-armed "halo."

Researchers also believe what remained of the disrupted galaxy is Omega Centauri, a cluster located 16,000 light-years from the Earth. The cluster contains thousands of stars as old as 11.5 billion years.

This new discovery will be published in the Monthly Notices of the Royal Astronomical Society. The study authors said the detection of new planets orbiting halo stars give us additional important knowledge about how planets were formed when the Milky Way was still younger.

According to outside researcher Richard Nelson from the Queen Mary University of London, the discovery of Kapteyn b could signal that many other possibly habitable planets will be found by astronomers in the next few years using observatories on the ground and in space.