Every time you follow the motion of a spacecraft, moon, planet or other object through the Solar System, you’re putting the theory of gravity to the test. On one hand, there’s a robust set of predictions for what the behavioral motion of these bodies ought to be, while on the other there’s what we actually observe. Sometimes, a mismatch indicates the need for something new, like a new planet or a new law of gravity.
But other times, there are mundane explanations that account for these “apparent” discrepancies, such as radioactive decay, heating from the Sun or the fact that the Earth rotates on its axis. Not all the phenomena of our Solar System have been explained, however, including the flyby anomalies and the changing perigee/apogee difference of the Moon.
Could there be new discoveries awaiting us on the other side of this? Find out thanks to Brian Koberlein!