Space is a vibrant and active environment, with different celestial bodies zipping through our solar system at a regular crypt. A comet called 2I/Borisov was first observed in 2019 and still passing through, while an asteroid called 'Oumuamua zipped by in 2017.
Recently, a new body of asteroids were discovered hanging around our solar system billions of years ago and has never left. These asteroids were likely around when our solar system was forming 4.5 billion years ago, having originated in a different star system. And when our solar system was forming, it was likely closer to other baby star systems as well.
"The close proximity of the stars meant that they felt each others' gravity much more strongly in those early days than they do today," said Fathi Namouni, researcher at the Observatoire de la Côte d'Azur and lead author of the study published in Monthly Notices of the Royal Astronomical Society, in a statement. "This enabled asteroids to be pulled from one star system to another."
"The discovery of a whole population of asteroids of interstellar origin is an important step in understanding the physical and chemical similarities and differences between solar system-born and interstellar asteroids," Maria Helena Moreira Morais at the Universidade Estadual Paulista in Brazil said in a statement."This population will give us clues about the sun's early birth cluster, how interstellar asteroid capture occurred and the role that interstellar matter had in chemically enriching the solar system and shaping its evolution."
The asteroids, known as Centaurs, that can be found in between Jupiter and Neptune. Centaurs are unusual because they resemble and act like both asteroids and comets, hence the name being evocative of the half-man/half-horse beings of folklore. These types of asteroids can be difficult to track or predict.
"The asteroid and Jupiter take the same amount of time to complete one orbit around the Sun, but one moves clockwise and the other counter-clockwise so they pass by each other twice per each full orbit," Morais wrote in 2018. "This pattern is repeated forever -- it is a stable configuration -- in a simplified model with only the Sun, Jupiter and the asteroid. We saw that when we include the other planets it is still very stable, over the solar system's age."