Potentially Dangerous Asteroid is Defying the Laws of Gravity

... well, sort of. Experts have determined that a massive asteroid that is due to orbit dangerously close to the Earth is actually composed of rubble spinning at an incredibly fast rate. Somehow, these surface rocks aren't tearing away from the whole to fly off into space, and astrophysicists are wondering why.

Now researchers at the University of Tennessee, Knoxville are suggesting that the asteroid, 1950 DA, is held together by van de Waals forces - cohesive forces never before detected on an asteroid.

According to the AAAS, 1950 DA first earned infamy in 2002, when astronomers announced that the nearly mile-wide (1.3 km) asteroid has a one in 300 chance of striking the earth in the year 2880. Since then, new observations have corrected that chance to one in 19,800.

Still, if the asteroid were even to brush earth, it would leave substantial damage in its wake. Whipping around the Sun every 2.2 years, 1950 DA is considered a relatively fast asteroid. It also has been found to revolve every 2.1 hours - a tenth of an hour faster than what was through the limit for centrifugal forces to hold rubble-like asteroids together.

Yet somehow, 1950 DA hasn't torn itself apart.

"If just gravity were holding this rubble pile together, as is generally assumed, it would fly apart. Therefore, interparticle cohesive forces must be holding it together," researcher Ben Rozitis said in a recent release.

Analyzing thermal images and orbital patterns, Rozitis and his colleagues Eric MacLennan and Joshua Emery theorized that 1950 DA's rotations is so fast at its equator, that it effectively experiences negative gravity.

"Following the February 2013 asteroid impact in Chelyabinsk, Russia, there is renewed interest in figuring out how to deal with the potential hazard of an asteroid impact," said Rozitis. "Understanding what holds these asteroids together can inform strategies to guard against future impacts."

He said that understanding van de Waals cohesive forces help keep asteroids together could effectively help experts develop ways to mitigate the threat of future potential asteroid impacts.

"With such tenuous cohesive forces holding one of these asteroids together, a very small impulse may result in a complete disruption," said Rozitis.

A study detailing these findings was published in the journal Nature on August 14.