This is an unusual 'dramatised documentary' with a rather misleading title (spoiler - no aliens encountered!), exploring what could happen if a very large object travelled through the Solar System. It was presumably inspired by the 2017 incident in which such an object, dubbed ʻOumuamua', made just such a fly-by. The one envisaged by BBC2 TV for their 90 minute prime-time programme has a similarly elongated shape but is very much larger and travelling at huge velocity. More to the point, it is first observed as a result of an apparently artificial signal received by the Voyager spacecraft in the 1420 megaherz channel for hydrogen, considered the most likely wavelength for interstellar communications. As a result of this and other characteristics it is determined that the object, dubbed 'Artefact' is artificial, but its trajectory poses no threat to Earth - nor is there any speculation concerning aliens (they are a serious and sober lot in BBC2!).
The programme contains a mixture of interviews with actual scientists, 'repurposed' news feeds and fictional podcasts 'to explore the scientific, social and philosophical implications of this occurence, as well as pondering the responses that such a meeting could evoke in communities across the globe'.
As the Artefact departs, attention focuses on where it came from. The trajectory reveals that it probably originated in 21 Sagittarius, at a location some 400 light years away, an area which is nearly twice as old as our system at 8 billion years. Given its velocity, the Artefact is probably about a billion years old, and may be just a fragment of a larger object.
Kudos to BBC2 for making such a worthy effort to explain serious issues to a popular audience. It is definitely worth watching, if you get the chance.
One detail - I was intrigued to discover that the United Nations has an "Office for Outer Space Affairs". Is there something that they are not telling us?