The so-called ‘alien asteroid’ is the first known, permanent resident of our solar system that originated from a different star system. The object, which orbits in the same path as Jupiter but in the opposite direction, may also be the oldest object in our solar system.
Scientists believe that it was attracted to our solar system by the gravitational forces of the sun and planets formed around 4.5 billion years ago. The asteroid is about three kilometres wide and orbits in the opposite direction to almost everything else in our solar system – something referred to as retrograde orbit.
While the composition of the asteroid, referred to as BZ, is unknown, it can be compared to that of the first-known object in our solar system called Oumuamua that was spotted last year and scientists have noted that they are quite different. Oumuamua “had only a short stay visa whereas BZ was issued a green card” said Dr Fathi Namouni in reference the the duration of the two objects’ respective stays.
BZ is observed in telescopes from Hawaii and Arizona and completes its orbit around the sun in the same amount of time as Jupiter, albeit in opposite directions.
It is said to have come into our solar system as a result of its original solar system interacting with other star systems to become a tightly packed cluster. The gravitational forces of these tightly packed star clusters force asteroids to come and go from within the solar system.
The continued monitoring of BZ could contain clues to the origins of life on Earth. Helena Morais, astronomer at Sao Paulo State University, said that the discovery lends itself to the presence of other asteroids in other solar systems and that “some of these may have collided with Earth…carrying water, biomolecules or even organic material.”