About 7 interstellar objects pass through the inner solar system every year, study estimates
In October 19th, 2017, the first interstellar object ever detected flew past Earth on its way out of the solar system. Less than two years later, a second object was detected, an easily identified interstellar comet designated as 2I/Borisov. The appearance of these two objects verified earlier theoretical work that concluded that interstellar objects (ISOs) regularly enter our solar system.