Astronomers have recently discovered a rogue asteroid that does not only travel in an opposite, retrograde orbit around the sun but also shares an orbital space with a planet.
The asteroid, dubbed as 2015 BZ509 or "Bee-Zed" for short, adds to a small list of asteroids (about 82) in our solar system that travel around the sun in a retrograde motion (clockwise) when visualized from above, while all other million or so asteroids travel in prograde motion (counter-clockwise). The researchers described the rogue asteroid in a paper published in Nature.
Despite going in an opposite direction in an orbital space occupied by planet Jupiter and its hoard of about 6,000 "trojan" asteroids, Bee-Zed has never collided with Jupiter or other asteroids for at least a million years.
According to the study, pure luck has nothing to do with Bee-Zed's success in avoiding Jupiter and other asteroids sharing the gas giant's orbital space. Jupiter's gravity plays a crucial role in deflecting Bee-Zed's path, allowing both the asteroid and the planet to continue safely on their orbits.
Actually, Jupiter and Bee-Zed never get too close with one another. The closest distance the two objects get to each other is about 109 million miles, roughly the distance between the Sun and the Earth,
"Given their relative sizes and the volume of space they orbit within, the odds are only about 1 in 1 billion of a collision each time BZ goes around its orbit. So the chances of BZ colliding with another Trojan asteroid are small," said Paul Wiegert, an asteroid expert at Western University and co-author of the study, in a report from Gizmodo.
First detected in January 2015, Bee-Zed is believed to be three kilometers in diameter and may have originated from the same place as the Halley's Comet.
So far, astronomers are still not sure whether Bee-Zed is an icy comet or a rocky asteroid. The astronomers expect Bee-Zed to have a stable orbit, even as an outlier, for at least a million more years.