Astronomers have spotted an incredibly rare'backwards' asteroid. Asteroid 2015 BZ509, also known as Bee-Zed, orbits the Sun in the opposite direction to the planets. It takes 12 years to make one complete orbit around the Sun - roughly the same time as Jupiter travelling in the opposite direction. Researchers predicted it two years ago, and have now been able to prove their theory was correct. Co-orbital bodies that orbit the Sun in the same direction as a planet can follow trajectories (blue curves with arrows) that, from the perspective of the planet, look like tadpoles, horseshoes or'quasi-satellites' It is estimated that only 82 of the more than 726,000 known asteroids are orbiting the'wrong way'.
Artist's concept of interstellar asteroid 1I/2017 U1 ('Oumuamua) as it passed through the solar system after its discovery in October 2017. If you could float above the plane of the solar system, you'd notice that more than 99.9 percent of the objects whirling around the sun orbit counter-clockwise, set into motion by the spinning disk of dust and gas that birthed our planets, asteroids, and comets. But bizarrely, of the more than 779,000 known asteroids, at least 95 drive against our solar system's flow of traffic. Now, two researchers are making an intriguing, if controversial, claim: One of these unusual asteroids--2015 BZ509--goes backward because it was adopted from another star system entirely. "When we started working, we did not want to know whether it was interstellar," says Fathi Namouni, an astronomer with the Côte d'Azur Observatory.
There's an asteroid in Jupiter's lane that orbits the sun in the wrong direction – and it may have been doing so for more than a million years. The asteroid 2015 BZ509 was discovered in 2015, orbiting near Jupiter but in the opposite direction. Like Jupiter and the other asteroids tied to its orbit, which are called Trojans, it takes 12 Earth years to orbit the sun. It is the only asteroid we know of that shares a planet's orbital space while moving in the opposite, or retrograde, direction. Paul Wiegert at the University of Western Ontario and his colleagues examined this strange orbit to figure out why BZ509 doesn't crash head-on into Jupiter.
BeeZed was discovered in 2014 by the Pan-STARRS 1 survey in Hawaii. If its distant origins are confirmed, it would not be the only interstellar visitor to our solar neighborhood: The asteroid'Oumuamua was spotted in late 2017 by Pan-STARRS 1 as it sped past Mars' orbit and toward Jupiter's. But'Oumuamua is on a one-way trip out of our solar system, whereas BeeZed seems to have settled down.
Last fall, an asteroid we named ʻOumuamua passed through the Solar System. Its visit marked the first time we've identified an object inside the Solar System that definitely came from outside. However, a new study argues that we might have a more permanent interstellar guest: a weird asteroid called 2015 BZ509. Fathi Namouni and Helena Morais performed a computer simulation which demonstrates that 2015 BZ509 could stay in its orbit for billions of years, but it's unlikely it formed there when the rest of the Solar System was born. Instead, the authors argue, it probably originated outside the Solar System and drifted in, where it was captured by gravity.