The detection of two celestial objects passing through our solar system can offer clues about exoplanets. 

On October 17 and 18, 2017, an unusual object quickly crossed the field of view of a large telescope near the top of a volcano on the Hawaiian island of Maui. This object, not bound by gravitational ties to the Sun or any other celestial body, was the first interstellar visitor observed passing through our solar system. Astronomers named it 11/‘Oumuamua, borrowing a Hawaiian word roughly translating to «first far-reaching messenger». Two years later, amateur astronomer Gennadiy Borisov discovered the only other known interstellar intruder, now named 21/Borisov, using his self-built telescope at the MARGO observatory in Nauchnij, Crimea. Unlike typical solar system asteroids and comets that orbit the Sun, ‘Oumuamua and Borisov are celestial nomads, spending most of their time wandering through interstellar space. Scientists now suspect these interstellar intruders are more common than previously thought, with potentially around 10,000 ‘Oumuamua-sized objects in Neptune’s orbit alone. These extraterrestrial objects could provide a new way to probe the characteristics of distant planetary systems, but more need to be found. Astronomers hope that the upcoming Legacy Survey of Space and Time at the Vera C. Rubin Observatory will increase the chances of finding these fast- moving objects. In the future, astronomers aim to create an interstellar object catalog similar to the exoplanet inventory, which could help answer questions about how typical the Earth and solar system are and provide clues about the composition of exoplanetary systems, including those that might harbor life.