An international research team led by Academy Research Fellow Mikko Kaasalainen from the University of Helsinki has found an asteroid whose rotation receives an extra kick from solar radiation. Asteroid 1862 Apollo’s diameter is about 1,5 km, it has a small moonlet, and its orbit crosses that of the Earth. The team reconstructed Apollo’s shape and determined its rotational state using brightness measurements from several years. They found that Apollo’s rotation speed steadily increases, and showed that this is due to the re-radiation of solar energy from its surface. The study is published online in „Nature“.
Acceleration of the rotation of asteroid 1862 Apollo by radiation torques