Scientists believe that many more such objects regularly pass by the Earth, with a number of them flying relatively near to us each year. But many of them go undetected, because they are hard to spot and it is difficult to know for sure where they have come from.

Astrophysicist Josep Trigo-Rodriguez of the Institute of Space Sciences near Barcelona, Spain, believes it is an interstellar object based on its odd path and extreme speed cutting through the solar system. He estimates its size at roughly 25 miles (40 kilometers) across.

Astronomers on Wednesday confirmed the discovery of an interstellar object racing through our Solar System -- only the third ever spotted, though scientists suspect many more may slip past unnoticed.Still,