Heliocentric orbit

A heliocentric orbit (also called circumsolar orbit) is an orbit around the barycenter of the Solar System, which is usually located within or very near the surface of the Sun. All planets, comets, and asteroids in the Solar System, and the Sun itself are in such orbits, as are many artificial probes and pieces of debris. The moons of planets in the Solar System, by contrast, are not in heliocentric orbits, as they orbit their respective planet (although the Moon has a convex orbit around the Sun).

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 "ἥλιος", meaning "Sun", and also Helios, the personification of the Sun in Greek mythology.^[1]

The first spacecraft to be put in a heliocentric orbit was Luna 1 in 1959. An incorrectly timed upper-stage burn caused it to miss its planned impact on the Moon.^[2]