Sun's long-lost twin could be in remote space, astronomers believe

Our sun may have a long lost twin at the far reaches of the solar system, a new study suggests.

The research, published in The Astrophysical Journal Letters, said traces of our sun's "temporary binary companion" are seen in the Oort cloud - a little-known region of comets and space rocks at the limits of the sun's influence.

NASA described the Oort cloud as "the most distant region of our solar system" and it is believed to hold billions of pieces of space debris the sizes of mountains and sometimes larger.

During its formation, massive chunks of rock and ice were catapulted into the Oort cloud from newly-formed solar system along with space debris from other planetary systems.

Researchers think that holds clues to our sun's long-lost twin, and is part of the binary system theory.

"Binary systems are far more efficient at capturing objects than are single stars," study co-author Avi Loeb said.

"If the Oort cloud formed as observed, it would imply that the sun did, in fact, have a companion of similar mass that was lost before the sun left its birth cluster."

Scientists believe the Oort cloud may have played important roles in Earth's history, such as causing the extinction of the dinosaurs.

It also holds clues for the mysterious Planet Nine that astronomers have yet to prove exists.

The discovery of Planet Nine, also known as Planet X, would further support the theory that the Sun has a twin, scientists believe.

But if the twin sun is out there, astronomers will probably never see it because of the gravitational influences of hundreds of billions of stars in the Milky Way.

"Passing stars in the birth cluster would have removed the companion from the sun through their gravitational influence," Mr Loeb said.

It could now be anywhere in the Milky Way.