Nasa has released the first findings from its report into unidentified anomalous phenomena, or UFOs.
The space agency commissioned the study in response to a variety of reports of what appear to be unexplained and unknown craft, reported by US pilots and others.
Nasa chief Bill Nelson said: “We are looking for signs of life, past and present, and it is in our DNA to explore and to ask why things are the way they are.”
Mr Nelson said the study was commissioned for a number of reasons, including “shifting sensationalism to science” and making sure information is shared “transparently around the world”.