Radio noise from just 11-light-years away
A signal from the star Ross 128 immediately piqued interest when it was discovered, because this red dwarf star was just 11-light-years away
– a stone's throw in the cosmos. Unfortunately, this had a rather more mundane explanation than some had hoped, but it was certainly exciting for a while.
In May 2017, researchers using the Arecibo Radio Observatory in Puerto Rico detected some rather unique radio waves coming from the direction of Ross 128. They were pulsing with a regularity that couldn't be explained by the star itself, leading the astronomers to dub this signal the 'Weird! Signal'. There was nothing else near the star that could seemingly explain the signals.
The structure of the signal itself led the team to think this was coming from deep space. The waves were coming in a variety of frequencies, suggesting the signal had traveled a long way through space. This effect, known as dispersion, would be the result of particles in interstellar space affecting the signal. This led to all sorts of theories, from a new type of solar flare to, yes, an alien civilisation.
The answer came two months later. Observing the star again, the astronomers discovered that the signals were not coming from deep space at all – they were actually coming from one or more satellites in geostationary orbit. The signal may have been reflected on its way to Earth, making it look like it had come from deep space.