Astronomical Two-For-One: Scientists Eyeing Asteroid Discover it Actually Has an Orbital 'Twin'

Friday, 13 July 2018 - 1:10PM
Space
Science News
Friday, 13 July 2018 - 1:10PM
Astronomical Two-For-One: Scientists Eyeing Asteroid Discover it Actually Has an Orbital 'Twin'
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Unsplash Composite/Bryan Goff
Sometimes in life you get more than you bargained for – NASA has just confirmed that a near-Earth asteroid is actually two asteroids locked together in orbit as they hurtle through the cosmos.

The discovery of asteroid 2017 YE5 is a saga spanning six months and four observatories from Morocco to California.

When it was first observed at the Oukaïmeden Observatory in late 2017, astronomers couldn't get a clear picture and struggled to make sense of the data.

Calculations revealed that the asteroid would make its closest approach to Earth for the next 170 years in June. If scientists were going to act, they had to do it now.

NASA's Goldstone Solar System Radar in the Mojave Desert captured the first images of 2017 YE5, but couldn't prove whether this asteroid was a binary system or rocky conjoined twins – and time was running out.


Then the Arecibo Observatory in Puerto Rico and the Green Bank Observatory in West Virginia did something amazing: using a technique called "bi-static radar configuration" Arecibo broadcasted a radar signal to detect 2017 YE5, which Green Bank then received.

Within two days both observatories declared that 2017 YE5 was the rare binary asteroid they'd been looking for.

Asteroid 2017 YE5 is remarkable (some would say downright weird) for several reasons.

Most binary asteroid systems are composed of one much-larger object and a smaller "moon" locked into its gravity. This system, however, is two objects measuring roughly 3,000 feet each. That's bigger than the Burj Khalifa skyscraper in Dubai: the tallest building in the world.

The asteroids also don't reflect as much light as objects this size should, leading astronomers to believe they're quite literally the color of charcoal. (Not ominous at all.)

They also reflected Arecibo's radar signals in very different ways. This creates more questions than it answers, since not one asteroid in the last fifty studied has exhibited the same phenomenon.

Unlike Oumuamua, asteroid 2017 YE5 will be back soon. The binary system orbits our Sun once almost every five years. Now that we know what we're looking at, we'll be able to ask smarter questions when the asteroid ventures back into our airspace.

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