What are Some Trans-Neptunian Objects?
Trans-Neptunian Object (TNO) is a blanket term that applies to any solid body orbiting the Sun beyond the orbit of Neptune. This includes Pluto and similar bodies called plutinos, the recently discovered Eris and other scattered disc objects, Kuiper belt objects, and many comets. The first trans-Neptunian object to be discovered was Pluto, in 1930. Between 1930 and 1992, no other trans-Neptunian objects were discovered besides Pluto’s moon, Charon. Around 1992, telescope technology improved to the point where many other trans-Neptunian objects could be resolved, and now over 1000 are known. Neptune is about 30 AU (Earth-Sun distances) from us, whereas trans-Neptunian objects include anything that orbits at distances between 30 AU to as far as 50,000 AU or more. Objects under the gravitational influence of the Sun extend as far as a light year, almost one-quarter of the way to the nearest star, Proxima Centauri. Most of these are comets which orbit in a hypothetical cluster called the O
