Back in May, the Arecibo Observatory in Puerto Rico detected strange radio signals coming from Ross 128, a red dwarf star 11 light-years away. After closely analyzing the data with the help of the Search for Extraterrestrial Intelligence (SETI) project, the team has now revealed what they believe to be the source of the signals – and it's bad news for little green men hunters.
According to the Arecibo astronomers, "the signals consisted of broadband quasi-periodic non-polarized pulses with very strong dispersion-like features," and they're unusual enough that the team has since dubbed the observation "The Weird! Signal," in an apparent reference to the 1977 Wow! Signal.
The astronomers put forward the three most likely explanations for the transmission: unusual stellar activity from the red dwarf, emissions from other background objects, or interference from satellite communications orbiting Earth.
Unfortunately, the most mundane of those turned out to be the culprit. The Arecibo team analyzed the data, backed up by observations from SETI using the Green Bank Telescope and the Allen Telescope Array, and has concluded that the Weird! Signal is most likely interference from geostationary satellites. Ross 128 is close to the celestial equator, which happens to be a busy patch of sky locally, and the signals are also within the range of frequencies that these satellites use to communicate.
That said, the team admits that the satellite solution leaves a few questions unanswered. Earthly origins don't quite account for the signals' "strong dispersion-like features," although this could be caused by multiple reflections. The researchers plan to continue looking into this scenario, as well as any others that might be a better fit.
Extraterrestrial intelligence was, of course, right at the bottom of the list of likely explanations. Intelligent life may ultimately have been responsible for these weird signals, but once again, it appears the call was coming from inside the house.