Nearly 50 years on, the "Wow!" signal continues to baffle scientists

For nearly 50 years, astronomers have been trying to solve the mystery of the signal that surprised scientist Jerry Ehman in 1977, who was conducting observations with the Big Ear radio telescope at Ohio State University. This signal lasted 72 seconds. However, it was so unusual and unique that Ehman wrote "Wow!" on the printout. A team of researchers from the University of Puerto Rico, led by astrobiologist Abel Méndez, is trying to explain its origin.

Méndez's team found four signals in archival data from the Arecibo Observatory that had frequencies similar to the famous "Wow!" signal. They come from the vicinity of Teegarden's star, a red dwarf close to Earth located 13 parsecs away. Scientists speculate that these signals may be related to clouds of cold hydrogen, which could also explain the origin of the original "Wow!" signal.

The mystery of the "Wow!" signal remains unsolved for nearly 50 years. Since then, it has become the source of much speculation about the existence of extraterrestrial civilisations. So far, it has not been possible to pinpoint the specific source of the signal definitively. However, a breakthrough might await us in this matter.

The "Wow!" signal did not move, so it is unlikely that it came from an artificial satellite. It has also never been repeated, making it likely that it was not intentionally transmitted. What's more, many natural objects emit signals at a frequency of 1420 MHz, which is exactly what Ehman received.

According to the hypothesis put forth by researchers from Puerto Rico, the signal could have been the result of a strong radiation burst passing through a cloud of cold hydrogen. This could have caused the emission of an intense radio pulse at a frequency of 1420 MHz. Such a phenomenon is called a maser.

It resembles a natural astrophysical laser emitting concentrated radio light. Although Teegarden's star is unlikely to be capable of triggering such a powerful burst, scientists suggest that other cosmic objects, such as magnetars, might be able to do so. Magnetars are neutron stars with extremely strong magnetic fields that can explode in bursts so powerful that we can detect them in intergalactic space.

Méndez's team's hypothesis seems to explain all the features of the "Wow!" signal. It is, therefore, possible that it was the first recorded astronomical maser burst along the hydrogen line. The researchers plan to continue their work by analysing archival data from the Arecibo Observatory. They hope that this may provide further evidence to support their theory. For now, the results of their research are available as a preprint on arXiv, with the full publication still to come.