Toy gyroscopes can do all kinds of interesting tricks. The most mysterious one, precession, seems to defy gravity. By definition, precession refers to a change in the orientation of the rotational ...

In the early 1600s, based on astronomical observations, Kepler established that the orbit described by a planet in the solar system is an ellipse, with the sun occupying one of its foci. Assuming that ...

With the expression “Blazars” scientists denote the most dramatic examples in the zoo of ac-tive galactic nuclei (AGN), accreting supermassive black holes in the centers of galaxies. They show up when ...