Oumuamua

ʻOumuamua was the first known interstellar object detected passing through our solar system in 2017. Its unusual elongated shape, unexpected acceleration, and lack of a visible cometary tail puzzled scientists. While most explanations are natural, such as outgassing, its peculiar traits led some astronomers to controversially speculate it could be an artificial object, like a light sail, suggesting the remote possibility of extraterrestrial technology.