This peculiar object has lived in our solar system for billions of years and researchers were finally able to take a look at it properly
For the first time, astronomers have been able to discover a permanent resident that found its home here when our solar system was in its early stages of development, somewhere around 4.5 billion years ago.
Such an object is called exo-asteroid, which translates to an “interstellar immigrant.” Exo-asteroid refers to the fact that the object originates from outside our solar system.
This asteroid was first spotted by the Pan-Starrs 1 telescope, which is located in Hawaii. The main reason why it was noticed by researchers is its orbit.
“The object was the first observational example of the type of orbits we were studying and we wanted to understand what was its origin,” Helena Morais, study author and professor of statistics at Sao Paulo State University in Brazil, said.
At first sight, the asteroid is nothing special; mostly, one of the many objects that orbit Jupiter. However, most of the objects in our solar system follow the same direction, which makes this specific asteroid special: it moves in the opposite direction, in a retrograde orbit.
“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. “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.”
Even more interesting is the fact that the asteroid kept its original path, the one it used to have in its native system and applied it here. If it was from our solar system, it would have borrowed the direction from both the gas and dust that formed all of the other planets.
However, the question remains: How did it get here?
“Stars form in packed groups called stellar nurseries and then later disperse as they move around the galaxy center,” Morais said. “Stars in these nurseries are so close to each other that they can exchange material amongst them by mutual gravitational interactions. Capture of 2015 BZ509 must have happened in the early stages of the solar system, about 4.5 billion years ago.”
Further information regarding this celestial object could be learned through observations of its composition.