Humanity has collected samples from three asteroids: the stony type, Itokawa, and the carbonaceous Ryugu and Bennu. Carbonaceous asteroids are the largest class, so it wouldn’t be too surprising that both Ryugu and Bennu are among them; still, their similarities might be a lot deeper than previously thought. New research puts forward a bold hypothesis: Bennu and Ryugu are siblings. The rest of this article is behind a paywall. Please sign in or subscribe to access the full content.

In the asteroid belt, there is a world called Polana. Today, it has a diameter of 55 kilometers (34 miles), but it was much larger in the past. Collisions broke it apart, and some of its fragments became asteroids in the main belt, now described as the Polana family. There might be others too, and some of them

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