There may be 4 quintillion alien spacecraft buzzing in our Solar System
The solar system is vast & the space between our star system and our closest neighbor, Proxima Centauri, is even more vast
Oumuamua: Asteroid that flew past Earth could have been a spacecraft sailing past us, Harvard scientists suggest
"A more exotic scenario is that 'Oumuamua' may be a fully operational probe sent intentionally to Earth vicinity by an alien civilization"