Interstellar objects

Until october 19, 2017, all objects enlightened by the Sun observed from the Earth or from space probes were belonging to our solar system, i.e. were orbiting around the Sun. Far objects from the Kuiper belt are also orbiting around the Sun even the duration of one revolution may be very long. Some small objects (asteroids or comets) may have a high eccentricity but always smaller than 1. Some could be newly belonging to the Solar system thanks to gravitational perturbations from nearby stars but they will remain orbiting around the Sun in the future.

On October 19, 2017, the Pan-starrs telescope observed a small objects -it was first supposed to be a comet- and after calculating its orbit, it appeared that its trajectory was hyperbolic with a sufficient velocity to escape the Solar system. It could come from outside of the Solar system and will leave it soon. In fact it was only deviated by the Sun before going away.

How to name such an object? It is impossible to model an orbit allowing to find the object in the future so that a new naming system was made for these objects. Such an observation was made possible thanks to the high sensitivity of new telescopes and it should possible to observe other objects of this type soon.

This new object received the following name: 1I/2017 U1. The naming was that of asteroids (2017 U1 provides the date of the discovery) with adding 1I. "1" because it is the first object of its kind and "I" for interstellar type. In spite that it would be impossible to have a definitive orbit around the Sun, it received the name "'Oumuamua" that means scout or messenger in polynesian language.