The Mystery Of 'Strange Signals' That Comes From A Star 11 Light-years Away

Astronomers who detected "strange signals" that appeared to come from a small, dim star have finally gotten to the bottom of the mystery.

Researchers first picked up what they now call the "Weird!" signal on May 12 using the Arecibo Observatory, a huge radio telescope built inside of a Puerto Rican sinkhole. (It's famous for appearing in the alien sci-fi movie "Contact".)

The signals appeared to come from Ross 128, a red dwarf star located about 11 light-years from Earth. The star is about 2,800 times dimmer than the sun and not yet known to have any planets.

Abel Méndez, an astrobiologist at the University of Puerto Rico at Arecibo, told Business Insider on July 14 that the star was observed for 10 minutes, during which time the signal was picked up and observed to be "almost periodic."

While Méndez and astronomers at the Search for Extraterrestrial Intelligence (SETI) Institute highly doubted that alien lifewas responsible, they wanted to be certain — so they began a new round of Arecibo observations on Sunday, July 16.

The "Weird!" signal detected by Arecibo Observatory.Planetary Habitability Laboratory/University of Puerto Rico at Arecibo

The fresh data took nearly a week to download from Arecibo's servers and analyze, and what they found won't please any alien-hunting hopefuls.

"The best explanation is that the signals are transmissions from one or more geostationary satellites," Méndez and his Arecibo colleagues wrote in a release provided to Business Insider.

Geostationary satellites orbit the Earth from about 22,236 miles high, which keeps them hovering over the same exact spot on the planet's surface. At the same time, however, they can hover very close to stars that astronomers are studying for extended periods of time.

"This explains why the signals were within the satellite frequencies and only appeared and persisted in Ross 128; the star is close to the celestial equator where many geostationary satellites are placed," the astronomers said.