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Astronomers have discovered that near Earth asteroid 1950DA is spinning so fast that gravity can’t hold it together. Instead, it is kept whole by cohesive forces called van der Waals forces, predicted but never detected before on an asteroid.
This is the coolest factoid from the article, however:
“We found that 1950 DA is rotating faster than the breakup limit for its density,” said Rozitis. “So 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.”
In fact, the rotation is so fast that at its equator, 1950 DA effectively experiences negative gravity. If an astronaut were to attempt to stand on this surface, he or she would fly off into space unless he or she were somehow anchored.
The important take away from this discovery is that it will be very easy to break this kind of asteroid up, turning a large and big threat into a collection of small but harmless rocks.