Astronomers have found five archaic planets around one of the oldest stars in the galaxy, forming the oldest planetary system ever found, leading to speculations that our Milky Way might possess some extremely ancient forms of life.

The planets were spotted while they circled a star called Kepler 444, which is situated 117 light years from Earth in the direction of Lyra, a constellation in the northern sky.

The variations in the brightness of the star were used by the researchers to calculate its age. The researchers claimed that the star located by them was among the first generation of stars to illuminate the Milky Way 11.2bn years ago.

According to astronomers, the Kepler 444 planetary system is more than twice as old as our own planetary system. They added the planets around Kepler 444 were already older than the Earth is today.

"This tells us that these kinds of planets formed very early in the history of the galaxy. If some fraction formed in the habitable zones around their host stars, then you have environments where life may develop, and it could have been there for a very long time," said Bill Chaplin, professor of astrophysics at the University of Birmingham.

Writing in The Astrophysical Journal, the scientists add: "Earth-size planets have formed throughout most of the Universe's 13.bn year history, leaving open the possibility for the existence of ancient life in the galaxy."

Astronomer and professor Dr. Sarbani Basu, who works at Yale, said the discovery also suggests that an ancient life could have been present in the universe.

NASA's Kepler space telescope was used by the astronomers to observe minute changes in the brightness of the stars. The careful observation showed that intensity of stars varies because sound waves trapped inside them make them contract and expand.