interstellar object detected passing through the Solar System. Formally designated 1I/2017 U1, it was discovered by Robert Weryk using the Pan-STARRS telescope
strange acceleration, without resorting to some sort of undetectable outgassing, is to assume that the object was propelled by solar radiation—essentially
begins to release gases when passing close to the Sun, a process called outgassing. This produces an extended, gravitationally unbound atmosphere or coma
planets. However it excludes hyperbolic bodies such as A/2019 G4 as well as 1I/ʻOumuamua and 2I/Borisov, two interstellar objects. back to top Extinct comet
in the popular press. As the second observed interstellar interloper after 1I/ʻOumuamua, it was given the "2I" designation, where "I" stands for interstellar