The barycenter of the Solar System, while always very near the Sun, moves through space as time passes depending on where other large bodies in the Solar System, such as Jupiter and other large gas planets, are located at that time. A similar phenomenon allows the detection of exoplanets by way of the radial velocity method. The helio- prefix is derived from the Greek word helios, meaning "sun", and also Helios, the personification of the Sun in Greek mythology.