Oumuamua: asteroid or alien light sail, debate continues five years later

This month it has been five years since a mysterious interstellar object, the first of its kind, that zipped through our solar system at a blistering 196000 miles or over 315000 kilometers an hour. Five years hence astronomers are still debating whether Oumuamua was an asteroid, a nitrogen iceberg, from another stellar system or an alien spacecraft, a light sail, sent by an advanced civilization.