<P> The definition of planet, since the word was coined by the ancient Greeks, has included within its scope a wide range of celestial bodies . Greek astronomers employed the term asteres planetai (ἀστέρες πλανῆται), "wandering stars", for star - like objects which apparently moved over the sky . Over the millennia, the term has included a variety of different objects, from the Sun and the Moon to satellites and asteroids . </P> <P> By the end of the 19th century the word planet, though it had yet to be defined, had become a working term applied only to a small set of objects in the Solar System . After 1992, however, astronomers began to discover many additional objects beyond the orbit of Neptune, as well as hundreds of objects orbiting other stars . These discoveries not only increased the number of potential planets, but also expanded their variety and peculiarity . Some were nearly large enough to be stars, while others were smaller than Earth's moon . These discoveries challenged long - perceived notions of what a planet could be . </P> <P> The issue of a clear definition for planet came to a head in January 2005 with the discovery of the trans - Neptunian object Eris, a body more massive than the smallest then - accepted planet, Pluto . In its August 2006 response, the International Astronomical Union (IAU), recognised by astronomers as the world body responsible for resolving issues of nomenclature, released its decision on the matter during a meeting in Prague in the Czech Republic . This definition, which applies only to the Solar System, states that a planet is a body that orbits the Sun, is massive enough for its own gravity to make it round, and has "cleared its neighbourhood" of smaller objects around its orbit . Under this new definition, Pluto and the other trans - Neptunian objects do not qualify as planets . The IAU's decision has not resolved all controversies, and while many scientists have accepted the definition, some in the astronomical community have rejected it outright . </P>

Give any three differences between planets and stars