The interstellar object, which could be an asteroid or a comet, has sparked huge enthusiasm from scientists who are urgently working to gather information on the mysterious body before it disappears from sight.
According to observers, the object is on a hyperbolic trajectory which suggests the body has escaped from a star from outside our solar system.
Early findings published in the International Astronomical Union's Minor Planet Centre (MPEC) state: "If further observations confirm the unusual nature of this orbit, this object may be the first clear case of an interstellar comet."
The mysterious object, called A/2017 U1, was discovered by the University of Hawaii's Pan-STARRS 1 telescope on Haleakala, Hawaii.
The alien space rock is less than a quarter mile (400 metres) in diameter and is believed to have come from the direction of the constellation Lyra, travelling through space at the remarkable speed of 15.8 miles (25.5 kilometres) per second.
Scientists have long believed in the existence of such interstellar objects because a lot of material is thought to be ejected from planetary systems when planets are formed but this is the first time they may have found one.