Space
'Oumuamua: The First Interstellar Visitor and the Mystery of Its Acceleration
On October 19, 2017, astronomers detected the first object ever confirmed to have originated outside our solar system. It was moving too fast, tumbling in an unusual way, accelerating when it shouldn't have been, and appeared to emit no gas despite behaving like a comet. Scientists have proposed it was a hydrogen iceberg, a nitrogen shard, or an alien probe. Here is what the evidence actually shows.