An Ancient, Lonely Asteroid Mysteriously Ended Up in the Outer Solar System

Wednesday, 09 May 2018 - 7:00PM
Space
Solar System
Wednesday, 09 May 2018 - 7:00PM
An Ancient, Lonely Asteroid Mysteriously Ended Up in the Outer Solar System
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ESO/M.Kornmesser
While there's plenty of asteroids on the edge of our solar system - there is an entire Kuiper Belt beyond Neptune, after all - they're distinctly different in their composition from anything in the main asteroid belt.

In the Kuiper Belt, you can find dwarf planets like Pluto, and lots of icy rocks because of how distant they are from the sun, but you're not likely to find any carbon-filled asteroids in them. That's because since the solar system's formation, these "carbonaceous asteroids" have been unique to the inner asteroid belt between Mars and Jupiter.

Why are we telling you all of this? So you can appreciate how weird it is that we just found an asteroid full of carbon inside the Kuiper Belt, the first known asteroid of its kind. A team of astronomers led by Tom Seccull of Queen's University Belfast have just used the Very Large Telescope in Chile to study a 181 foot (291 meter) asteroid named 2004 EW95, and have conclusively determined it has carbon inside it.

This means the asteroid was almost certainly formed inside the main asteroid belt, so how did it end up on the far end of the solar system? The team of astronomers have some ideas.



There's a good chance that 2004 EW95 is extremely old, having first been formed in the asteroid belt and then moving to the Kuiper belt all within the earliest days of our solar system's formation. Models of the early solar system are often chaotic, with planets and other bodies getting flung around before things settled into steadier orbits, and the best explanation for this lonely carbon asteroid is that it was launched out there during this primordial chaos.

According to Seccull, who said the following in a press release from the European Southern Observatory (which manages the Very Large Telescope): 

Opening quote
"The reflectance spectrum of 2004 EW95 was clearly distinct from the other observed outer Solar System objects. It looked enough of a weirdo for us to take a closer look... Given 2004 EW95's present-day abode in the icy outer reaches of the Solar System, this implies that it has been flung out into its present orbit by a migratory planet in the early days of the Solar System."
Closing quote


We haven't confirmed that 2004 EW95 is out there for this reason, and we're not entirely sure how old it is, either. Being rather small and incredible distant, it's been difficult to study - the team's research, just published in the Astrophysical Journal Letters, detail the first good look we've ever gotten at this asteroid. 

And as always, now that we've found one displaced asteroid orbiting on our solar system's fringes, there's very likely even more out there. So now astronomers have something new to look out for.
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