When planning to defend Earth against asteroids on collision courses, the most cinematic option is to blow the thing to pieces. But that would probably be the worst thing to do, thanks to the discovery that common rubble-pile asteroids are held together by little more than gravity and cohesion.

The study, published today in the journal Nature, focused on asteroid (29075) 1950 DA, which is famous for being one of the closest asteroids to Earth and one of the most likely to impact the planet in the next several centuries.

1950 DA also is also something of a riddle to planetary scientists. They noticed that the body is spinning slightly faster than expected given its rubble and dust composition.

Alexandra Witze, reporting for Nature News: