SETI Archives

February 25, 2013April 26, 2016 by Jason Major

Pluto May Soon Have a Moon Named Vulcan (Thanks to William Shatner)

These may soon be the names of Pluto's family of moons (Hubble image: NASA, ESA and M. Showalter/SETI)

The votes have been tallied and the results are in from the SETI Institute’s Pluto Rocks Poll: “Vulcan” and “Cerberus” have come out on top for names for Pluto’s most recently-discovered moons, P4 and P5.

After 450,324 votes cast over the past two weeks, Vulcan is the clear winner with a landslide 174,062 votes… due in no small part to a little Twitter intervention by Mr. William Shatner, I’m sure.

In other words… yes, the Trekkies have won.

During a Google+ Hangout today, SETI Institute senior scientist Mark Showalter — who discovered the moons and opened up the poll — talked with SETI astronomer Franck Marchis and MSNBC’s Alan Boyle about the voting results. Showalter admitted that he wasn’t quite sure how well the whole internet poll thing would work out, but he’s pleased with the results.

“I had no idea what to expect,” said Showalter. “As we all know the internet can be an unruly place… but by and large this process has gone very smoothly. I feel the results are fair.”

As far as having a name from the Star Trek universe be used for an actual astronomical object?

“Vulcan works,” Showalter said. “He’s got a family tie to the whole story. Pluto and Zeus were brothers, and Vulcan is a son of Pluto.”

And what can you say when even Mr. Spock agrees?

The other winning name, Cerberus, is currently used for an asteroid. So because the IAU typically tries to avoid confusion with two objects sharing the same exact name, Showalter said he will use the Greek version of the spelling: Kerberos.

Cerberus (or Kerberos) is the name of the giant three-headed dog that guards the gates to the underworld in Greek mythology.

Now that the international public has spoken, the next step will be to submit these names to the International Astronomical Union for official approval, a process that could take 1–2 months.

(Although who knows… maybe Bill can help move that process along as well?)

Read more about the names on the Pluto Rocks ballot here, and watch the full recorded Google+ Hangout below:

February 11, 2013April 26, 2016 by Jason Major

Help Name Pluto’s Newest Moons!

Pluto's known system of moons (NASA/ESA/M. Showalter))

Today marks seven months since the announcement of Pluto’s fifth moon and over a year and a half since the discovery of the one before that. But both moons still have letter-and-number designations, P5 and P4, respectively… not very imaginative, to say the least, and not really fitting into the pantheon of mythologically-named worlds in our Solar System.

Today, you can help change that.

According to the New Horizons research team, after the discovery of P4 in June 2011 it was decided to wait to see if any more moons were discovered in order to choose names that fit together as a pair, while a*lso following accepted IAU naming practices. Now, seven months after the announcement of P5, we think a decision is in order… and so does the P4/P5 Discovery Team at the SETI Institute.

"Hey, I can be democratic about this!" — “Hey, I can be democratic about all this!”

Today, SETI Senior Research Scientist Mark Showalter revealed a new poll site, Pluto Rocks, where visitors can place their votes on a selection of names for P4 and P5 — or even write in a suggestion of their own. In line with IAU convention these names are associated with the Greek and Roman mythology surrounding Pluto/Hades and his underworld-dwelling minions.

“In 1930, a little girl named Venetia Burney suggested that Clyde Tombaugh name his newly discovered planet ‘Pluto.’ Tombaugh liked the idea and the name stuck. I like to think that we are doing honor to Tombaugh’s legacy by now opening up the naming of Pluto’s two tiniest known moons to everyone.”

– Mark Showalter, SETI Institute

As of the time of this writing, the ongoing results look like this:

Results of Pluto Rocks voting as of Feb. 11, 2013 at 10 am EST (15:00 UT)

Do you like where the voting is headed? Are you hellishly opposed? Go place your vote now and make your opinion count in the naming of these two distant worlds!

(After all, New Horizons will be visiting Pluto in just under two and a half years, and she really should know how to greet the family.)

Voting ends at noon EST on Monday, February 25th, 2013.

The SETI team welcomes you to submit your vote every day, but only once per day so that voting is fair.

UPDATE: On Feb. 25, the final day of voting, the tally is looking like this:

PlutoRocks results as of Feb. 25, 2013 - Vulcan is in the lead, thanks to publicity from Mr. William Shatner — PlutoRocks results as of Feb. 25, 2013 – Vulcan is in the lead, thanks to publicity from Mr. William Shatner

Thanks in no small part to a bit of publicity on Twitter by Captain Kirk himself, Mr. William Shatner (and support by Leonard Nimoy) “Vulcan” has made the list and warped straight to the lead. Will SETI and the IAU honor such Trek fan support with an official designation? We shall soon find out…

February 8, 2013December 23, 2015 by Nancy Atkinson

Less Than 1% of Exoplanet Systems Have Intelligent Life, Researchers Say

Recent findings say that Earth-like exoplanets could be all around us in our cosmic neighborhood. But how many would be home to intelligent life?

A new study estimates that fewer than 1% of transiting exoplanet systems host civilizations technologically advanced enough to send out radio transmissions that could be detected by our current SETI searches.

That equates to less than one in a million stars in the Milky Way Galaxy that would have intelligent life we could possibly communicate with. But even with those odds, there could be millions of advanced ET’s in the galaxy that we could phone, researchers say.

A group of astronomers, including Jill Tarter from the SETI Institute and scientists at the University of California, Berkeley used the Green Bank Telescope in West Virginia to look for intelligent radio signals from planets around 86 of stars where the Kepler mission has found transiting exoplanets. These specific targets were chosen because they had exoplanets in the habitable zone around the star and there were either five or more exoplanets in the system, or there was super-Earths with relatively long orbits.

The search came up empty in detecting any signals.

“We didn’t find ET, but we were able to use this statistical sample to, for the first time, put rather explicit limits on the presence of intelligent civilizations transmitting in the radio band where we searched,” said Andrew Siemion from UC Berkeley.

The team looked for signals in the 1-2 GHz range which is the region we use here on Earth for our cell phones and television transmissions. Narrowing it down, the team looked for signals that cover no more than 5Hz of the spectrum since there is no known natural mechanism for producing such narrow band signals.

“Emission no more than a few Hz in spectral width is, as far as we know, an unmistakable indicator of engineering by an intelligent civilization,” the team said in their paper.

The telescope spent 12 hours collecting five minutes of radio emissions from each star. Most of the stars were more than 1,000 light-years away, so only signals intentionally aimed in our direction would have been detected. The scientists say that in the future, more sensitive radio telescopes, such as the Square Kilometer Array, should be able to detect much weaker radiation, perhaps even unintentional leakage radiation, from civilizations like our own.

The researchers said these results allows them to put limits on the likelihood of Kardashev Type II civilizations. The Karashev scale is a method of measuring a civilization’s level of technological advancement, based on the amount of energy a civilization is able to utilize. The team said that finding no signals implies that the number of these civilizations that are “noisy” in the 1-2GHz range must less than one in a million per sun-like star.

The team plans more observations with the Green Bank Telescope, focusing on multi-planet systems in which two of the planets occasionally align relative to Earth, potentially allowing them to eavesdrop on communications between the planets.

“This work illustrates the power of leveraging our latest understanding of exoplanets in SETI searches,” said UC Berkeley physicist Dan Werthimer, who heads the world’s longest running SETI project at the Arecibo Telescope in Puerto Rico. “We no longer have to guess about whether we are targeting Earth-like environments, we know it with certainty.”

Read the team’s paper.

Sources: UC Berkeley, MIT Technology Review

November 13, 2012January 4, 2016 by Nancy Atkinson

SETI: The Search Goes On

In this new video, SETI founder Frank Drake and astronomer Jill Tarter about why the search of the cosmos is important and needed. Visit SETI online to learn more about the search for signals of extraterrestrial life using radio telescopes on Earth and how you can help.

September 19, 2012December 23, 2015 by Elizabeth Howell

SETI Astronomer Jill Tarter Recalls ‘Contact,’ 15 Years On

In 1985, famed astronomer, author and TV host Carl Sagan invited Jill Tarter to dinner at his house near Cornell University. Tarter, heavily involved with the Search for Extra-Terrestrial Intelligence, gladly accepted the chance to speak with Sagan, a member of SETI’s board of trustees.

Seated with Sagan and his wife, Ann Druyan, Tarter learned that Sagan had a fiction book on the go.

“Annie said, ‘You may recognize someone in the book, but I think you’ll like her,'” Tarter recalled in an interview with Universe Today.

Suspecting the character was based on herself, Tarter’s response to Druyan was: “‘Just make sure she doesn’t eat ice cones so much.’ It was something I was teased about.”

Female, in a male-dominated field

It was 15 years ago this month that the movie Contact, based on Sagan’s book of the same title, expanded to a run in international theatres after a successful summer in North America. The movie explores the implication of aliens making contact with Earth, but does it from more of a scientific perspective than most films.

While Contact, the movie did not talk about the pi sequences or advanced mathematical discussions in Contact, the book, it did bring concepts such as prime numbers, interference with radio telescopes, and the religion vs. science debate to theatres in 1997.

Tarter, who has just retired as the long-time director of the SETI Institute, said she was stunned by the parallels between her own life and that of Ellie Arroway, the character based on her in Contact. Both lost parents at an early age. Both also had to make their way in a field aggressively dominated by males.

Tarter recalls a meeting with fellow female scientists of her generation some years ago.

“A huge percentage of us had been, in high school, either cheerleaders or drum majorettes. This is so counterintuitive, right? Because we’re the nerds, we’re the brainy ones … (it was because) we were all competitors, and there weren’t any (female) sports to compete at. These sports were open, and we competed, and we generally won.”

Working on set

Tarter cautions the parallels did not totally match. The hopes and aspirations of Ellie in the book, and also the movie, were products of Sagan’s imagination. But the producers and actors of the film did want to get a close sense of what it was like to work with SETI.

After Jodie Foster was cast as Ellie, there were multiple phone calls between the actress and Tarter to discuss SETI.

“From her point of view, she was clear she wasn’t going to teach anyone astronomy. She was interested, in a personal way, about what the scientists were like,” Tarter said.

When the crew was filming at the Arecibo Observatory in Puerto Rico, Tarter flew there to observe the work, meet with Foster and also show the actress around. Tarter recalls bringing Foster up in a cabin that had a perfect view of the telescope, some 500 feet above the dish.

Microphones and walkie-talkies

Filming was an interesting process for Tarter, as well. There were the microphones, and the tools the crew used to check continuity. Most amusingly for Tarter, she observed Foster (reported height 5 feet, 2 inches) needing to stand on a box for most of the close-up shots with actor Matthew McConaughey (reported as 6 feet tall).

Two errors still irk Tarter today. There is a scene when Ellie gives a modified version of the Drake Equation, which calculates the odds of intelligent life who are capable of communicating with other life forms, and the calculations are all wrong. “It’s really infuriating,” Tarter said.

The other large mistake is a scene where Ellie gets a potential signal from space, while working at the Karl G. Jansky Very Large Array set of radio telescopes in New Mexico.

“She’s sitting in the middle of the array, in a car, with her laptop, and she gets the signal. And the first thing she does is pick up a walkie-talkie and start broadcasting. That signal is going to wipe out the signal from the sky. You don’t transmit by walkie-talkie.”

But overall, Tarter said the movie did a great job at portraying the feel of SETI. And Foster appreciated Tarter’s help. “She would write me handwritten thank-you notes, which was a kind of manner that most people have lost. A great courtesy.”

Hollywood outreach

Tarter walked the red carpet at the movie premiere and spent most of her time watching the film in tears of happiness. That euphoria evaporated when she saw the SETI Institute was not credited at the end of the film. When she talked to one of the film producers, she said she was informed that lawyers usually draft agreements specifying the length of time the credit appears, and the compensation received for doing so.

“We don’t have a lawyer at the SETI Institute,” she said. “When I write a paper, I acknowledge my collaborators. We got that wrong, so we never got any credit. We might have gotten even more recognition.”

But the professional connection with Foster still remains. Foster happily responded to a request from Tarter to do voice-overs for a video clip used for a SETI high school curriculum for integrated science. She also narrated a show, Life: A Cosmic Story, for the California Academy of Sciences Morrison Planetarium.

Tarter is now shifting into full-time outreach for SETI, saying the budgetary problems that shut down the organization’s Allen Telescope Array for several months last year were a warning call.

One of the organization’s newest initiatives is SETILive.org, which crowdsources analysis of signals from the Kepler Field. SETI solicits the public to take some time looking at the signal patterns, one at a time, in search of extraterrestrial communications.

“SETI is too important to allow it to fail,” Tarter said, adding her focus is finding substantial, stable funding from “that individual or institution that is capable of taking a long view.”

June 5, 2012December 23, 2015 by Nancy Atkinson

First SETI Search of Gliese 581 Finds No Signs of ET

An artist’s impression of Gliese 581d, an exoplanet about 20.3 light-years away from Earth, in the constellation Libra. Credit: NASA

[/caption]

The first targeted SETI search of a system with a potentially habitable world has come up empty, but perhaps finding signals wasn’t the main objective in this search. Back in 2007 a group of astronomers used the Australian Long Baseline Array to listen for radio signals from Gliese 581, a red dwarf star that is now known to host at least six planets, with one in the star’s habitable zone. This was a SETI-type search for extraterrestrial-made signals, and it initially found 222 candidate signals. However, the team was able to reject all of them using automated analysis techniques, determining they were caused by Earth orbiting satellites. So why is this potentially good news?

This search was actually a proof of concept for using the Very Long Baseline Interferometry (VLBI) for targeted SETI searches, and that it worked well is great news for future searches that look specifically at a particular star system. Until recently most SETI searches were wide sky surveys, scanning wide, random areas of space looking for radio signals. But now, with the success of the exoplanet hunting Kepler mission, we now know of some potentially habitable systems and planets, and astronomers can do targeted searches, looking at specific spots in the sky.

It wasn’t known if the VLBI technique would be successful for such a “directed” targeted search, but this search by Hayden Rampadarath and team from the International Centre for Radio Astronomy Research at Curtin University in Australia proves it does.

The Australian Long Baseline Array is a combination of three radio antennae: the 22-meter Mopra Telescope, Parkes Observatory and the Australia Telescope Compact Array (ATCA) which are each a few hundred kilometers apart from each other. The data from the three locations are combined, making them act as one huge radio telescope, with an extraordinary angular resolution in the milli-arcsecond regime, the highest resolution in astronomy. And it turns out that VLBI techniques are great for SETI searches because they automatically exclude many Earth-based sources of interference that might otherwise look like SETI signals. That’s because the same signals have to show up at all the telescopes several hundred kilometers apart.

The team pointed the telescopes at Gliese 581 (Gl581), located 20 light-years distant in the constellation Libra for about 8 hours, tuning into frequencies close to 1500 megahertz.

The team said that the array would have been able to pick up a broadcast with a power output of at least 7 megaWatts per hertz, which means that if Gliese inhabitants had been broadcasting directly to Earth using an 300-meter Arecibo-style dish, the signals would have easily been picked up. However, ordinary radio transmissions, such as the ones Earthlings regularly transmit into space, would have been too weak to be detected.

But this bodes well for using other more powerful VLBI arrays such as the European VLBI Network, current most-sensitive VLBI array in the world or the upcoming Square Kilometre Array, which will have the sensitivity to pick up broadcasts of a few kilowatts per Hertz from 20 light years away.

So while this doesn’t mean that there is no life in the Gliese 581 system, this does mean we now have an expanded arsenal of tools for looking.

Read the team’s paper.

Source: Technology Review Blog

May 24, 2012April 26, 2016 by Jason Major

Aliens Don’t Want To Eat Us, Says Former SETI Director

Don't worry Ridley, she just wants to explore.

[/caption]

Alien life probably isn’t interested in having us for dinner, enslaving us or laying eggs in our bellies, according to a recent statement by former SETI director Jill Tarter.

(Of course, Hollywood would rather have us think otherwise.)

In a press release announcing the Institute’s science and sci-fi SETIcon event, taking place June 22 – 24 in Santa Clara, CA, Tarter — who was the inspiration for Jodie Foster’s character in the film “Contact” — disagreed with both filmmakers and Stephen Hawking over the portrayal of extraterrestrials as monsters hungry for human flesh.

“Often the aliens of science fiction say more about us than they do about themselves,” Tarter said. “While Sir Stephen Hawking warned that alien life might try to conquer or colonize Earth, I respectfully disagree. If aliens were able to visit Earth that would mean they would have technological capabilities sophisticated enough not to need slaves, food, or other planets. If aliens were to come here it would be simply to explore.

“Considering the age of the universe, we probably wouldn’t be their first extraterrestrial encounter, either. We should look at movies like ‘Men in Black III,’ ‘Prometheus’ and ‘Battleship’ as great entertainment and metaphors for our own fears, but we should not consider them harbingers of alien visitation.”

Tarter, 68, recently announced her stepping down as director of SETI in order to focus on funding for the Institute, which is currently running only on private donations. Funding SETI, according to Tarter, is investing in humanity’s future.

“Think about it. If we detect a signal, we could learn about their past (because of the time their signal took to reach us) and the possibility of our future. Successful detection means that, on average, technologies last for a long time. Understanding that it is possible to find solutions to our terrestrial problems and to become a very old civilization, because someone else has managed to do just that, is hugely important! Knowing that there can be a future may motivate us to achieve it.”

On the other hand, concern that searching the sky for signs of life — as well as sending out your own — could call down hungry alien monsters would make a good case for keeping quiet. And a quiet search may not get the necessary funding to keep going. I can see where Tarter is coming from.

Let’s just hope she’s right. (About the eating part, at least.)

May 22, 2012April 26, 2016 by Nancy Atkinson

Alien Hunter Jill Tarter Changing Her Focus

[/caption]

After thirty-five years of listening for extra-terrestrial intelligence, astronomer Jill Tarter is stepping down from the research and will now be doing a more Earthly task: making sure there’s enough money for SETI to continue its search.

Tarter, who was the inspiration for the character Ellie Arroway in Carl Sagan’s novel and film “Contact,” announced today that Dr. Gerry Harp will step into the directorship role at SETI, “to continue our strong tradition of excellent research, freeing me up to focus on finding stable funding for it. I want to make the endowment of SETI research a success, so that my colleagues now, and in the future, can focus on the search for extraterrestrial intelligence for all of us.”

Tarter, 68, signed on to the NASA SETI program in the 1970s when a small group of NASA researchers were developing novel equipment and strategies to make systematic radio SETI observations. Since the decision by Congressional in 1993 to no longer fund the program, she has led the efforts at the non-profit SETI Institute to continue the work. Tarter spearheaded a decade-long program, dubbed Project Phoenix, that used large antennas in Australia, Puerto Rico and West Virginia to examine approximately one thousand nearby star systems over an unprecedented wide range of radio frequencies. Astronomers suspected that planets existed around other stars, but that was only a hypothesis – until 1995. Recently NASA’s Kepler telescope, launched in 2009, has discovered thousands of new planetary systems, some of them containing planets as small as the Earth.

“Kepler has been a paradigm shift—starting with the first data release in 2010 and second in 2011 and third in 2012, we have altered our SETI search strategy. We are no longer pointing our telescopes at Sun-like stars in hopes of finding something; we are now observing stars where we KNOW there are planets. Exoplanets are real. We’ve gone from having 20-30 potential targets to having thousands of targets. Kepler is telling us WHERE to look, and we are focusing there,” said Tarter.

SETI research is now only funded by private donations, “limiting how quickly we can search these newly discovered planets for intelligent life,” said Tarter. “The best reason to support SETI research is because it is an investment in our own future. The scientist Phil Morrison said that ‘SETI is the archeology of the future.’ Think about it. If we detect a signal, we could learn about THEIR past (because of the time their signal took to reach us) and the possibility of OUR future. Successful detection means that, on average, technologies last for a long time. That’s the only way another technological civilization can overlap with us in time and space. Understanding that it is possible to find solutions to our terrestrial problems and to become a very old civilization, because someone else has managed to do just that, is hugely important! Knowing that there can be a future may motivate us to achieve it.”

Tarter will be both celebrated and be one of the featured speakers at the gala dinner during the SETI Institute’s public event, SETIcon II, to be held at the Santa Clara Hyatt Hotel on June 22 – 24. See here for information on how to attend.

To give a donation to SETI, see their website.

May 1, 2012December 23, 2015 by Jason Major

Fragments of Meteorite Worth Their Weight in Gold

Fragments collected from the April 22 fireball over central California. (Franck Marchis)

[/caption]

Actually it’s more like 3.5 times their weight in gold, according to today’s market value… and meteorite experts from SETI and NASA’s Marshall Space Flight Center.

During the daylight hours of April 22, 2012, reports came in from all over the north central California area of an extremely bright fireball — described as a “glittering sparkler” — and accompanying loud explosion. It was soon determined that this was the result of a meteoroid about the size of a minivan entering the atmosphere and disintegrating. It was later estimated that the object weighed about 70 metric tons and detonated with a 5-kiloton force.

Over a thousand meteorite hunters scrambled to the area, searching for any traces of the cosmic visitor’s remains. After a few days, several pieces of the meteorite were found and reported by five individuals, adding up to 46 grams in total.

Those pieces could be worth over $9,000 USD, according to Bill Cooke of NASA’s Meteoroid Environment Office at Marshall Space Flight Center.

Based on today’s market, that’s about 3.6 times the value of gold (about $1,660 per troy ounce — 31.1 grams).

The high value is due to the extreme rarity of the meteorite fragments. The California fireball is now known to have been created by a CM chondrite, a type of carbonaceous meteorite with material characteristics similar to comets.

FMarchis — SETI Institute's Franck Marchis and the chondrite fragments (F. Marchis)

According to Franck Marchis, Planetary Astronomer at the Carl Sagan Center of the SETI Institute and one of the coordinators of the meteorite reporting teams, CM chondrites appear to have been altered by water, and have deuterium-to-hydrogen ratios in line with what’s been measured in the tails of comets Halley and Hyakutake.

They also have been found to contain organic compounds and amino acids, lending to the hypothesis that such meteorites may have helped supply early Earth with the building blocks for life.

But due to their fragile composition, they are also incredibly rare. Only 1% of known meteorites are CM chondrites, making even the small handful of fragments found in California very valuable.

“This will be only the third observed CM fall in the US, after Crescent, OK, in 1936, (78 g) and Murray, KY, in 1950 (13 kg),” Marchis told Universe Today.

As far as what the finders will do with the fragments, that’s entirely up to them.

“They can sell them on eBay or they can lend them to the scientists… or make a donation.” Marchis said.

Just goes to show that all that glitters really isn’t gold — it could be even better.

Read more in an article by Sara Reardon on New Scientist, and read more on the comet/chondrite connection here. And the ongoing search for pieces of what’s now being referred to as the “Sutter’s Mill Meteorite” can be followed here and here.

The largest CM chondrite ever recovered was from a fall in Murchison, Australia on September 28, 1969. The total mass of its collected fragments weighed in at over 100 kg (220 lbs).

February 24, 2012March 26, 2022 by Paul Scott Anderson

35 Years Later, the ‘Wow!’ Signal Still Tantalizes

The "Wow!" signal. Credit: Wikimedia Commons

Since the SETI program first began searching for possible alien radio signals a few decades ago, there have been many false alarms but also instances of fleeting signals of interest which disappeared again as quickly as they had appeared. If a potential signal doesn’t repeat itself so it can be more carefully observed, then it is virtually impossible to determine whether it is of truly cosmic origin. One such signal in particular caught astronomers’ interest on August 15, 1977. The famous “Wow!” signal was detected by the Big Ear Radio Observatory at Ohio State University; it was thirty times stronger than the background noise but lasted only 72 seconds and was never heard again despite repeated subsequent searches.

In a new book titled The Elusive Wow, amateur astronomer Robert Gray chronicles the quest for the answer to this enduring puzzle.

When the signal was first seen in the data, it was so pronounced that SETI scientist Jerry Ehman circled it on the computer printouts in red ink and wrote “Wow!” next to it. It appeared to fit the criteria for an extraterrestrial radio signal, but because it wasn’t heard again, the follow-up studies required to either confirm or deny this were not possible. So what was it about the signal that made it so interesting?

First, it did appear to be an artificial radio signal, rather than a natural radio emission such as a pulsar or quasar. The Big Ear telescope used a receiver with 50 radio channels; the signal was only heard on one frequency, with no other noise on any of the other channels. A natural emission would cause static to appear on all of the frequencies, and this was not the case. The signal was narrow and focused, as would be expected from an artificial source.

The Big Ear Radio Observatory. Credit: Big Ear Radio Observatory / North American AstroPhysical Observatory / Ohio State University

The signal also “rose and fell” during the 72 seconds, as would be expected from something originating in space. When the radio telescope is pointed at the sky, any such signal will appear to increase in intensity as it first moves across the observational beam of the telescope, then peak when the telescope is pointed straight at it and then decrease as it moves away from the telescope. This also makes a mere computer glitch a less likely explanation, although not impossible.

What about satellites? This would seem to be an obvious possible explanation, but as Gray notes, a satellite would have to be moving at just the right distance and at just the right speed, to mimic an alien signal. But then why wasn’t it observed again? An orbiting satellite will broadcast its signal repeatedly. The signal was observed near the 1420 MHz frequency, a “protected spectrum” in which terrestrial transmitters are forbidden to transmit as it is reserved for astronomical purposes.

There may be a bias in thinking that any alien signals will be like ours which leak out to space continuously, ie. all of our radio and TV broadcasts. That is, “normal” radio emissions from every-day type technologies which could easily be seen on an ongoing basis. But what if they were something more like beacons, sent out intentionally but only on a periodic basis? As Gray explains, radio searches to date have tended to look at many different spots in the sky, but they will only examine any particular spot for a few minutes or so before moving on to the next. A periodic signal could easily be missed completely, or if seen, it may be a long time before it is seen again.

Of course, it is also possible that any other civilizations out there might not even use radio at all, especially if they are more advanced than us (while other intelligent life might be behind us, as well). A newer branch of SETI is now searching for artificial sources of light, like laser beams, used as beacons.

So where does this leave us? The “Wow!” signal still hasn’t been adequately explained, although various theories have been proposed over the years. Perhaps one day it will be observed again, or another one like it, and we will be able to solve the mystery. Until then, it remains a curiosity, a tantalizing hint of what a definite signal from an extraterrestrial civilization might look like.

More information is available at the Big Ear Radio Observatory website.