Posted by Davin Flateau on 10 Aug 2005 at 1:45 pm.
Filed under Astronomy.
It seems that objects in our Universe are rarely alone. Most of the stars you see in the night sky are actually made up of two or more stars, we know that planets in our own solar systems often have one or more moons. We’ve even discovered double asteroids orbiting one another such as Gaspra and its little attendant Ida. So scientists speculated that the next step would be to discover a triple asteroid, or even more. Can you imagine multiple asteroids all orbiting each other while making their way together around the sun?
Many astronomers and science fiction authors have. And now, astronomers with the European Southern Observatory have announced that they’ve actually found a triple asteroid!
The discovery was made with Yepun, one of ESO’s 8.2-m telescopes of the Very Large Telescope Array at Cerro Paranal (Chile), using the outstanding image’ sharpness provided by the adaptive optics NACO instrument. Via the observatory’s proven “Service Observing Mode”, Marchis and his colleagues were able to obtain sky images of many asteroids over a six-month period without actually having to travel to Chile.
“Since double asteroids seem to be common, people have been looking for multiple asteroid systems for a long time,” said Marchis. “I couldn’t believe we found one.”
The asteroid is 87 Sylvia, a well-known object that’s one of the largest inhabitants on the main asteroid belt. It’s shaped like a potato, and measures a whopping 380 x 260 x 230 kilometers. It also spins very quickly, at a rate of once every 5 hours and 11 minutes. Astronomers have named the two new small asteroids orbiting around 87 Sylvia Romulus and Remus, and they’re tiny by comparison at 7 km and 18 km wide respectively.
It certainly qualifies as a discovery that was hiding in plain sight - just waiting for the right equipment and people to uncover its true nature!
You can see an animation of what this waltzing trio might look like if you could visit (13 MB .mov)
“It is most probably a “rubble-pile” asteroid”, Marchis added. These asteroids are loose aggregations of rock, presumably the result of a collision. Two asteroids smacked into each other and got disrupted. “The new rubble-pile asteroid formed later by accumulation of large fragments while the moonlets are probably debris left over from the collision that were captured by the newly formed asteroid and eventually settled into orbits around it. Because of the way they form, we expect to see more multiple asteroid systems like this.”
