Interstellar asteroids and comets: planetary dynamics meets galactic dynamics
Paul Wiegert
The University of Western Ontario



In 2017, the first asteroid to enter our Solar System from interstellar space was discovered at the Pan-STARRS telescope in Hawaii, and has now been named 'Oumuamua, a Hawaiian term which signifies 'Messenger from Afar'. In 2019 a second interstellar visitor, comet Borisov (named after its discoverer) appeared. Curiously, they have contrasting properties: 'Oumuamua is rocky and relatively slow (both unexpected beforehand) while Borisov is the reverse: icy and fast. Much could be learned about this new class of object if we knew their sources and/or the mechanism(s) by which they are produced, both of which are uncertain. I'll outline some of the efforts being made to back-track these puzzling visitors to their points of origin, somewhere within our Milky Way galaxy.