Astronomers regularly study asteroids in order to understand what the different celestial bodies were made of in the past, as well as in order to trace how they were located. Most asteroids are located in the asteroid belt, between Jupiter and Mars. It is too far from Earth, so astronomers cannot study the appearance of asteroids and their composition. But sometimes the asteroid changes its orbit and approaches the Earth, so it can be photographed and partially studied.
This is how the photographs of Bennu and Ryugu turned out: these are asteroids, they are classified as those that were formed from many small pieces and debris. Only gravity holds them together. Astronomers have noted that asteroids have an unusual diamond shape.
Previously, scientists believed that the shape of the rhombus was due to rotation: the material of the asteroid moved from the poles to the equator. But when scientists modeled the shape and motion of asteroids, they were flat and asymmetrical.
The authors of the new work found that in these models was missing a key factor – the deposition of the material. Imagine that sand or sugar is poured through a funnel: as a result, they form a conical pile. Similar models, which take into account the various forces acting on the object, were used by the authors for asteroids.
Thus, instead of a conical shape, a diamond-shaped one turned out: the centrifugal force caused by rotation decreases near the poles of the asteroids, so this is where material accumulates.