In 1977, the Big Ear Radio Telescope at Ohio State University captured a strong narrowband signal from space. The signal was a continuous radio wave that was very strong in intensity and frequency and had many expected characteristics of extraterrestrial transmission. This event will become known as Wow! Signal and he remains the strongest candidate for a message sent by an alien civilization. Unfortunately, all attempts to determine the source of the signal (or rediscover it) failed.
This has led many astronomers and theorists to speculate about the origin of the signal and what type of civilization may have sent it. In a recent series of articles, amateur astronomer and science communicator Alberto Caballero offered some fresh insights on Wow! A signal and extraterrestrial intelligence in our space neighborhood. In the first article, he explores nearby Sun-like stars to identify a possible source of the signal. In the second, he assesses the spread of hostile alien civilizations in the Milky Way galaxy and the likelihood that they will invade us.
Almost fifty years after it was discovered, Wow! The signal continues to irritate and cannot be explained. In recent years, attempts have been made to attribute comets to the edge of our solar system, an explanation that the astronomical community has since rejected. In 2020, interest in this candidate for the ETI signal was revived when Cabelaro identified a sun-like star near the sky where Wow appeared! The signal was detected. If the analysis is correct, this known signal may have come from a sun-like star located 1,800 light-years away.
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Summary, Wow! The signal was discovered by the now-defunct Ohio State University Radio Observatory (nicknamed the “Big Ear”), which was commissioned for SETI research in 1973 after completing an extensive study of extragalactic radio sources. In the summer of 1977, astronomer Jerry R. Eman volunteered for the project and was tasked with analyzing vast amounts of data printed on linear paper. On August 15, he noticed a series of values showing enormous intensity and increasing frequency.
Ehman bypassed the alphanumeric designation for this signal (6EQUJ5) and wrote “Wow!” Next to it. In recent years, coinciding with the 35th anniversary of the discovery of the signal, there has been renewed interest and research into this mysterious event. This should come as no surprise, given how the most likely candidate for an alien message remains. Although (from all accounts) the continuous wave was unmodulated, there were several indications at the time that the signal was not natural in origin.
On the one hand, the signal is heard only on one frequency, without noise in any of the 50 other Big Ear radio channels. This is incompatible with natural emissions that cause statics at other frequencies while Wow! The signal was narrow and focused – what we would expect from the broadcast radio signal. Second, the signal “rose and fell” in the 72 seconds it was detected. This is in line with signals from space, which increase in intensity as they move across the sky and approach the telescope’s radio, then decrease as they move away from the telescope.
Third, the signal was observed near 1420 MHz, a “protected frequency” on which it is forbidden to transmit Earth-based transmitters because they are reserved for astronomical research. All this indicated that the signal was extraterrestrial in origin, as satellites and terrestrial radio sources would be repeated in nature until Wow! The signal seemed to be a one-time event. Based on the time and orientation of the Big Ear telescope, astronomers concluded that it must have come from somewhere in the direction of the constellation Sagittarius.
The mystery of Wow! The signal has long been of interest to Alberto Caballero Diez, a Spanish exoplanet hunter, SETI researcher and scientific communicator. While Caballero studied criminology at the University of Santiago de Compostela in Spain, he has since focused his efforts on the study of habitable exoplanets and extraterrestrial intelligence. He even started relying on one of his hobbies (day trading) to fund his extraterrestrial intelligence (SETI) efforts.
He is perhaps best known as the host of The Exoplanets Channel, a YouTube channel for exoplanet research, SETI and interstellar travel. He is also known for coordinating the Habitat Exoplanet Hunting Project (HEHP), an international network of professional and amateur astronomers dedicated to the study of exoplanets in nearby stellar systems. In particular, the project hopes to find potentially habitable exoplanets around non-flammable stars G (yellow dwarf), K (orange dwarf) or M (red dwarf) within 100 light years from Earth.
“The project is a worldwide network of professional and amateur optical observatories looking for potentially habitable exoplanets around nearby stars using the transit method,” Caballero told Universe Today by email. “I founded the project in 2019. [S]since then, more than 30 observatories on five continents have joined. “
In 2020, HEHP announced the discovery of an exoplanet the size of Saturn orbiting the habitable zone of its parent star. This is the first discovery of an exoplanet made entirely by amateur astronomers. Also in 2020, Caballero observed a Sun-like star, almost identical to our Sun (Solar Analogue), while searching for the sector of the sky where Wow! The signal was detected. Caballero described this discovery through The Exoplanets Channel (episode below) and in an article * published in the International Journal of Astrobiology in early May.
In this article, Caballero explores nearby Sun-like stars using data from the ESA Gaia Observatory (collected in the Gaia Archives) and identified the most likely source. The study contains a sample of 66 yellow G-type dwarfs (similar in size and spectra to the Sun) and orange K-type dwarfs (slightly smaller and darker than the Sun). It narrows it down to a candidate star located about 1,800 light-years from the solar system. This was 2MASS 19281982-2640123, a perfect solar analogue, comparable in size, mass and spectra to the Sun. As Caballero said:
“By searching the ESA Gay Archive for stars with a mass, radius and brightness similar to the Sun. I rejected the red dwarfs because a large percentage of them emit eruptions that destroy exoplanetary atmospheres, and we don’t know which of these data are erupting stars.
The similarities between this star and our Sun make it the most likely place to find life and a possible civilization (as we know it). At the same time, the distance is in line with previous research by Italian astronomer Claudio Macone. In 2010, Maccone conducted a statistical analysis **, where it concluded (with 75% confidence) that the nearest ETI would be between 1,000 and 4,000 light-years away. As Caballero explained, this makes 2MASS 19281982-2640123 an ideal candidate for subsequent applicants for possible techno-signatures.
These conclusions raise another interesting point that goes directly to the heart of the whole “listen or communicate” debate (also known as SETI and METI). While SETI’s efforts consist of listening to space for signs of possible extraterrestrial transmission (“passive SETI”), Extraterrestrial Intelligence (METI or “active SETI”) consists of composing messages that are transmitted into space. In that regard, Wow! The signal is a perfect example of passive SETI effort, while the Arecibo message is a perfect example of active SETI or METI.
In his second article, + Caballero addresses this problem by performing a statistical analysis of possible hostile civilizations in our galaxy and the ability of one or more of them to detect signals coming from Earth (and possibly choose to invade). As radio antennas and radars are constantly emitting signals into space, Cabelero believes a risk assessment is needed. As he explained, this consists in using the last century of Earth’s history as a template, a century in conflict:
“I have estimated the frequency of invasions on Earth over the last 100 years. Only 51 countries out of 195 invaded another. I have found that over time and the development of humanity, the frequency of invasions has decreased. Extrapolating the results to humanity once it becomes a Type-1 civilization capable of traveling between stars, the frequency and therefore the likelihood of invasion decreases. Estimates are based on life as we know it. ”
In addition, Caballero turned this same analysis to humanity and the possibility of becoming a “malicious civilization” after becoming a Type 1 civilization on the Kardashev scale. A civilization at this level of development would be able to use all the energy on its planet and limit interstellar travel to nearby stellar systems. His analysis showed that a maximum of four malicious civilizations will be within the scope of our broadcasts. As Caballero said, this shows that the invasion of aliens is not the greatest existential threat facing humanity:
“The low estimated risk, lower than the probability of a killer asteroid hitting planets, may support METI’s efforts. SETI is needed, but it’s like looking for a needle in a haystack. If we really want to have a chance to come into contact with aliens, we need to start broadcasting laser messages to thousands of exoplanets. Whether we have to do it or not depends on what the international community is saying. “
Statistically, METI may not pose the existential risk that some say it could. Certainly no more than threats that are …
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