FAQ (Frequently Asked Questions)

Has the SETI Institute found an extraterrestrial signal yet?

No SETI search has yet received a confirmed, extraterrestrial signal. If we had, you would know about it. There is no policy of secrecy, and no way to enforce it even if there were (whenever Project Phoenix has a signal that looks interesting for even a few hours, the newspapers start ringing our phones!)

In the past, there were several unexplained and intriguing signals detected in SETI experiments. Perhaps the most famous of these was the "Wow" signal picked up at the Ohio State Radio Observatory in 1977. However, none of these signals was ever detected again, and for scientists that's not good enough to claim success and boogie off to Stockholm to collect a Nobel Prize. You wouldn't believe cold fusion unless researchers other than the discoverers could duplicate it in their labs. The same is true of extraterrestrial signals: they are credible only when they can be found more than once.

When will success occur? No one knows. It could happen tomorrow, or it could take many years. Maybe it will never occur. But the only way to find out is to do the experiment.

What is Project Phoenix?

Project Phoenix, run by the SETI Institute, was the most ambitious search for extraterrestrial intelligence ever undertaken. From 1995 - 2004, it scrutinized the vicinities of nearby, Sun-like stars, hoping to pick up a signal that would tell us that we're not alone.

Project Phoenix It was a targeted search. In other words, rather than sweeping large swaths across the sky, Phoenix zeroed in on nearby stars. By restricting its attention to carefully selected targets, the 28 million channel Phoenix receiver can accumulate radio energy for minutes (rather than seconds), providing unequaled sensitivity to weak signals.

Project Phoenix also checked out all signal candidates within 20 minutes of their discovery, using a second radio telescope in Jodrell Bank, England.

How do we know if the signal is from ET? 

Virtually all radio SETI experiments have looked for what are called "narrow-band signals." These are radio emissions that are at one spot on the radio dial. Imagine tuning your car radio late at night… There's static everywhere on the band, but suddenly you hear a squeal - a signal at a particular frequency - and you know you've found a station.

Narrow-band signals, say those that are only a few Hertz or less wide, are the mark of a purposely built transmitter. Natural cosmic noisemakers, such as pulsars, quasars, and the turbulent, thin interstellar gas of our own Milky Way, do not make radio signals that are this narrow. The static from these objects is spread all across the dial.

In terrestrial radio practice, narrow-band signals are often called "carriers." They pack a lot of energy into a small amount of spectral space, and consequently are the easiest type of signal to find for any given power level. If E.T. is a decent (or at least competent) engineer, he'll use narrow-band signals as beacons to get our attention.  

What happens if we find something? 

Keep in mind that the receivers used for SETI are designed to find constant or slowly pulsed carrier signals… something like a flute tone against the noise of a waterfall. But any rapid variation in the signal - known as modulation, or more colloquially as the "message" - would be smeared out and lost. In order to understand anything that E.T. might be saying to us, we'll have to build far larger instruments to look for the modulation of his signal. It's more than likely that, once a detection is made, the money will become available to build this far larger instrument.

Until we can measure the modulation, all we'll know is that there is intelligence out there. We can pinpoint the spot on the sky where the signal is coming from, and slow changes in its frequency will tell us something about the rotation and orbital motion of E.T.'s home planet. Even with this limited information, the detection of alien intelligence will be an enormously big story. We'll know we're not alone, and we're not the smartest things in the universe. And of course there will be a loud clamor to build the big dishes that would allow eavesdropping on E.T.'s message.

Then what? Suppose we get the message? Will we understand it? No one knows, of course. It's conceivable that an advanced and altruistic civilization will send us simple pictures and other information.  

Is someone hiding aliens?

We don't think so. Many Americans (and quite a few citizens of other countries) are convinced that extraterrestrials may be buzzing the countryside in their spacecraft, or occasionally alighting in the back yard to abduct a few humans for breeding experiments.

This would be of enormous interest and importance of course, and (in our opinion) impossible to hide, particularly if it's happening internationally. The presence of aliens on our planet is not something you would want to hide: it would be the biggest science story of all time, and tens of thousands of university researchers would be working away on it. However, despite the popularity of aliens on both silver and phosphor screens and a half-century of UFO sightings, the lack of credible physical evidence has made it difficult for serious scientists to believe that UFOs have anything to do with extraterrestrial visitors.

What is SETI?

SETI is an acronym for Search for Extraterrestrial Intelligence. It is an effort to detect evidence of technological civilizations that may exist elsewhere in the universe, particularly in our galaxy. There are potentially billions of locations outside our solar system that may host life. With our current technology, we have the ability to discover evidence of cosmic habitation where life has evolved and developed to a technological level at least as advanced as our own.

What is the SETI Institute?
The SETI Institute is a non-profit corporation that serves as an institutional home for research and educational projects relating to the study of life in the universe. The Institute conducts research in a number of fields including astronomy and planetary sciences, chemical evolution, the origin of life, biological evolution, and cultural evolution. Institute projects have been sponsored by NASA Ames Research Center, NASA Headquarters, the National Science Foundation, the Department of Energy, the US Geological Survey, the Jet Propulsion Laboratory (JPL), the International Astronomical Union, Argonne National Laboratory, the Alfred P. Sloan Foundation, the David & Lucile Packard Foundation, the Paul G. Allen Foundation, the Moore Family Foundation, the Universities Space Research Association (USRA), the Pacific Science Center, the Foundation for Microbiology, Sun Microsystems, Hewlett Packard Company, other private industry, William and Rosemary Hewlett, Bernard M. Oliver and many other private donations. The Institute welcomes support from private foundations or other groups/individuals interested in SETI.

Each funded effort is supervised by a principal investigator who is responsible to the Board of Trustees for the conduct of the activity. There are currently over two dozen active projects at the Institute investigating Mars, planetary science, exobiology and related topics. Project Phoenix is a unique research effort; it is the SETI Institute's search for extraterrestrial intelligence, and is the Institute's largest project. It is funded entirely by private donations.

Who works at the SETI Institute?
The Institute employs scientists, engineers, administrators, technicians, public outreach specialists, educators and other support staff.

Didn't NASA have a SETI program
Yes. The NASA effort was called the High Resolution Microwave Survey (HRMS). In 1993, Nevada Senator Richard Bryan successfully introduced an amendment that eliminated all funding for the NASA SETI program. The cost of the program was less than 0.1% of NASA's annual budget, amounting to about a nickel per taxpayer per year. The Senator cited budget pressures as his reason for ending NASA’s involvement with SETI.

So who funds the SETI search now?
Current SETI searches are funded by a few major donors (such as William Hewlett, David Packard, Gordon Moore, Paul Allen, and Barney Oliver), foundations and many individuals.

II. SETI Institute Research/Technical Information

What is the Allen Telescope Array?
An array of antennas which can be simultaneously used for both SETI and cutting-edge radio astronomy research.
Because it will have the ability to study many areas on the sky at once, with more channels and for 24 hours a day, the Allen Telescope Array will permit an expansion of Project Phoenix's stellar reconnaissance to 100 thousand or even 1 million nearby stars.

The Allen Telescope Array is located at the Hat Creek Observatory in the Cascades just north of Lassen Peak (California).

Thanks to the far-sighted benevolence of technologists Paul Allen (co-founder of Microsoft) and Nathan Myhrvold (former Chief Technology Officer for Microsoft), this new telescope array idea will soon become a reality.

What is Project Phoenix? 
Project Phoenix was the name of the SETI Institute's research project to search for extraterrestrial intelligence that ran from 1995-2004. The name derives from the mythological Egyptian bird that rose from the ashes of its own demise -- in the case of SETI, the ashes of congressional funding cuts. After the HRMS Targeted Search was canceled, the Institute quickly moved to retain the core science and engineering team of that effort, and with help from its subcontractors, upgraded and expanded the Targeted Search electronics and software. That equipment is now being used to search the vicinities of nearby stars for signs of technological civilizations, the core activity of Project Phoenix. In addition to conducting this mammoth search, the SETI Institute is also spurring a parallel effort to design and develop systems of much greater capability, as well as supporting other research and educational projects. Since February, 1994 all this work has been supported by private donations  

  How did Project Phoenix search for extraterrestrial intelligence?
Project Phoenix used the world's largest telescopes (40 to 300 meters in diameter) to scrutinize the vicinities of nearby, sun-like stars. Stars were examined one by one over a portion of the microwave region of the electromagnetic spectrum for artificially produced signals. The Targeted Search System looks for signals in the range 1,000 MHz to 3,000 MHz, with a frequency resolution of 1 Hz. The ability to detect slowly-drifting signals and the application of near real-time data processing made Project Phoenix the most comprehensive and sensitive SETI search in the world at the time. The actual time needed will depend on the availability of radio telescopes, the level of terrestrial radio frequency interference, the rate at which improvements can be made to receiving systems, and, of course, whether or not an extraterrestrial signal is detected.   

Why do you think an extraterrestrial civilization will broadcast in the microwave frequency band?
There is relatively little background static from galaxies, quasars, and other cosmic noisemakers in the microwave part of the spectrum. This makes faint signals easier to pick out. Additionally, the microwave band contains a naturally-produced emission line, a narrow-band "broadcast", at 1,420 MHz due to interstellar hydrogen. Every radio astronomer (including extraterrestrial ones) will know about this hydrogen emission. It may serve as a universal "marker" on the radio dial. Consequently, it makes sense to use nearby frequencies for interstellar "hailing" signals.   

How do you know if you've detected an intelligent, extraterrestrial signal?
The main feature distinguishing signals produced by a transmitter from those produced by natural processes is their spectral width, i.e. how much room on the radio dial do they take up? Any signal less than about 300 Hz wide must be, as far as we know, artificially produced. Such narrow-band signals are what all SETI experiments look for. Other tell-tale characteristics include a signal that is completely polarized or the existence of coded information on the signal. Unfortunately, SETI searches are burdened with confusion caused by narrow-band signals from our own planet. Military radar and telecommunications satellites produce such signals. Project Phoenix uses a second telescope to sort out this unwanted interference. Since the second telescope is hundreds of miles away from the main instrument, an extraterrestrial signal will have a slightly different frequency at the two sites. This is because of the Earth’s rotation and the effect of Doppler shift. Looking for the expected slight shift in frequency at the two telescopes is a good way to judge which signals are local, and which are truly extraterrestrial.

That depends. If the signal is strong enough, it might still be detected with current SETI equipment, although weak broadcasts will be missed. There's little doubt that in the future, with greatly increased computer capability, our search will encompass these other types of communications. Nonetheless, it's good to keep in mind that any civilization will realize that narrow-band broadcasts are the most efficient in terms of producing a detectable signal at the receiving end. If they wish to get in touch or, for example, simply have high-powered radars for finding incoming comets, they will generate the type of signals our experiments can find.

Has the Institute detected a signal from ET? 
Not yet. You may have heard of interesting "candidate" signals found by SETI searches other than Phoenix, for example the famous "Wow" signal found at the Ohio State Radio Observatory in 1977. Because data collected in these searches were often processed long after the observation, candidate signals could not be immediately checked to see if they were of extraterrestrial origin. Subsequent observations conducted days to months after the original observations have never detected any of the candidate signals again. In order to be sure that a signal is from another civilization -- in order to have it accepted as real by the scientific community -- it must be independently verified and shown to originate from a point beyond the solar system. Project Phoenix immediately tests all candidate signals.

If we do find a truly extraterrestrial signal, you will know about it. The procedures to be followed in case of such a discovery are outlined in the Post-Detection Protocol.  

  How significant are unexplained signals?
Not very. As described immediately above, the Institute's SETI searches can immediately check out candidate signals. So far, none has proven to be extraterrestrial, but instead are radar, telecommunications satellites, etc. Finding a signal once, but never again, is unconvincing evidence.

A well-known signal picked up in 1977 by SETI researchers at Ohio State University is known as the "Wow" signal. However, it was never seen a second time, and is presumed to be unidentified interference.

Are we also sending any signals? We conduct a passive experiment, designed only to look for signals, not to send them. However, humankind has been unintentionally transmitting signals into space – primarily high-frequency radio, television, and radar – for more than fifty years. Our earliest TV broadcasts have reached about one thousand nearby stars, although any alien viewers would have to build a very large antenna to detect them.

SETI researchers have not been very interested in broadcasting because of the long time one has to wait for a reply. If the nearest civilization is 100 light-years away, we would have to sit around for 200 years for a reply to a deliberate broadcast. Nonetheless, a few, mostly symbolic, intentional messages have been sent. One message, transmitted in 1974 from the Arecibo Observatory, was a simple picture describing our solar system, the compounds important for life, the structure of the DNA molecule, and the form of a human being. The message was transmitted in the direction of the globular star cluster M13, about 25,000 light years away.

If an extraterrestrial civilization has a SETI project similar to Project Phoenix, could they hear Earth?
In general, no. Most earthly transmitters are too weak to be detectable by Phoenix-type equipment at the distance of even the nearest star. The exceptions are some high-powered radars and the Arecibo broadcast of 1974 (which lasted for only three minutes). To detect "leakage" radiation similar to our own will require instruments that are many times more sensitive than what we now have.   

Why can't we just send a spacecraft out to look for other planets and life orbiting other stars?
The stars are simply too far away. Our best rockets travel at about 10 miles per second. Even to reach the nearest other star system, Alpha Centauri, at about 4.2 light-years’ distance, would take such a rocket 60,000 years. There are about a thousand stars like the Sun within 100 light-years of us. To investigate them all with spacecraft would take millions of years and vast amounts of money. A better scheme is to search for radio waves (which travel at the speed of light) now, with state-of-the-art technology, and at a relatively modest cost. The annual budget of Project Phoenix is $4-5 million dollars, provided entirely by donors.  

Will the senders have any way of knowing that their signal has been received?
No. They wouldn’t be aware that we had received their message any more than a radio disk jockey knows that you’ve tuned in his show. For the extraterrestrials to know, we would have to send a message in reply. The SETI Institute has no plans for replying. Under an International SETI Post-detection Protocol now under consideration, the nations of the Earth would decide together whether and how to reply. It is worth noting, however, that a complete message exchange might take decades due to the finite speed of light.   

What happens if you do detect a signal?
The first thing to do is to confirm that it’s truly extraterrestrial. Remember, with tens of millions of channels and antennas that are among the world’s largest, SETI picks up signals frequently. An important test to verify that a signal is truly extraterrestrial would be a confirming observation at another radio telescope.

Once an artificial signal is confirmed as being of extraterrestrial intelligent origin, the discovery will be announced as quickly and as widely as possible. A Declaration of Principles Concerning Activities Following the Detection of Extraterrestrial Intelligence, endorsed by six international space organizations, describes how to make such an announcement. The SETI Institute has a plan of action that resembles the Declaration of Principles. There will be no secrecy, and indeed getting the word out quickly is important, as there would be an urgent need to have astronomers world-wide monitor any detected signal, 24 hours a day.  

  What happens if you don't detect a signal?
 We are just scratching the surface of what a modern search can do. Failure to find a signal wouldn’t prove that we’re the only thinking beings in the Galaxy. After all, absence of evidence is not evidence of absence.

The SETI Institute intends to press the search. Needless to say, the march of technology and new scientific discoveries will influence future SETI strategies. But giving up is not in the cards. Christopher Columbus did not turn around simply because he failed to find any new lands during his first few days at sea.   

How would you know what the signal means?
Note that our search, like other SETI searches, is intended to find the "carrier" signal that would underpin any transmission. A carrier is just a simple tone, and doesn't convey any information itself. The message, if there is any, might require new instruments, and could be much weaker.

If we do succeed in finding a message, could we understand it? If the signal is intentional, it might be decipherable. In order to send or receive a signal over interstellar distances, a civilization must understand basic science and mathematics. Hence, a message from another civilization might use science and math to build up a common language with other socieites. Signals sent by a civilization for its own purposes may be impossible for us to unravel. But one thing we would know irrespective of content is that another intelligent civilization is out there.  

  Where is the search done?
We are currently using the Allen Telescope Array. In order to quickly verify whether a signal is truly extraterrestrial or merely earthly interference, we always use a second, generally smaller telescope located hundreds of miles from the primary instrument

How long have astronomers been looking for extraterrestrial signals?
The first scientific paper on using radio waves to transmit information over interstellar distances was published in the magazine Nature in 1959 by physicists Phillip Morrison and Giuseppe Cocconi. In the following year, Frank Drake (now Chairman of the Board of the SETI Institute) conducted the first radio search for evidence of technology in other solar systems using an 85-foot antenna at the National Radio Astronomy Observatory in Green Bank, West Virginia. Drake called his search Project Ozma, and observed two sun-like stars which are about 12 light years away. Since then, more than 60 searches have been conducted by dozens of astronomers in several countries. However, note that the technology of today's searches dwarfs that of earlier efforts. Project Phoenix is estimated to be 100 trillion times more effective than Project Ozma.

Project Phoenix was the only targeted star search running, and was unsurpassed in sensitivity and comprehensive coverage of frequencies and signal types. It is noteworthy that Project Phoenix observations during 1997 and early 1998 took place at the same observatory used by Drake in 1960, although on a far larger telescope. Note that SETI activities represent only a tiny fraction of the use of radio telescopes world-wide. More than 99% of radio astronomy is non-SETI research.  

  Who else is carrying out searches?
Astronomers from the University of California, Berkeley, are carrying out a search called SERENDIP IV at the Arecibo Observatory in Puerto Rico. About 3% of these data are made available for processing by the popular SETI@home screen saver software. The Planetary Society, an independent, privately funded organization, operated Project BETA at Harvard University (this search was stopped in 1999 due to damage to the telescope in a wind storm) and in Argentina. Ohio State University conducted a full-time search with a large volunteer effort for 24 years; however, this search ended in 1997 when the university shut down the radio telescope they used. New optical SETI programs are being conducted at the Univ. of California Berkeley's Leuschner Observatory and at Harvard University. Other radio searches are underway in Australia (see links to the SETI Australia Centre) and Italy. Additional SETI experiments, on a smaller scale, have been, and continue to be, conducted by individual scientists and radio amateurs in the United States and other countries.

Has any SETI search found anything?
No confirmed, artificially-produced extraterrestrial signal has ever been found. However, all previous searches have been limited in one respect or another. These include limits on sensitivity, frequency coverage, types of signals the equipment could detect, and the number of stars or the directions in the sky observed. For example, while there are hundreds of billions of stars in our galaxy, less than a thousand have been scrutinized with high sensitivity.

Many SETI searches have found unexplained signals, but unless a signal can be found repeatedly and confirmed by other telescopes, it won’t meet the stringent requirements set by scientists for a true detection.

  Why do we think that life is "out there"?
Over the last half-century, scientists have developed a theory of cosmic evolution that predicts that life is a natural phenomenon likely to develop on planets with suitable environmental conditions. Scientific evidence shows that life arose on Earth relatively quickly, suggesting that life will occur on similar planets orbiting sun-like stars. With the recent discoveries of extrasolar planetary systems, and the suggestive evidence that life may once have existed on Mars, this scenario appears even more likely.

Additionally, one should keep in mind that we are only one planet around a very ordinary star. There are roughly 400 billion other stars in our Galaxy, and nearly 100 billion other galaxies. It would be extraordinary if we were the only thinking beings in all these enormous realms.   

What is the Drake Equation?
The Drake Equation, originally developed as an agenda for a 1961 scientific meeting, provides a way of estimating the number of intelligent civilizations existing in our galaxy that might be broadcasting signals. Among the factors considered are the number of sun-like stars in our galaxy, the fraction of habitable planets supporting communicating civilizations, etc. When these various factors are multiplied together one can compute N, the number of transmitting civilizations. Unfortunately, many of the factors are poorly known, so estimates of N range from one (we are alone in the Galaxy) to thousands or even millions.  

  Why do SETI at all?
There are many reasons, including such practical considerations as the technological spinoff. The signal processing techniques used for Project Phoenix have already been applied to the detection of breast cancer. But SETI research is first and foremost pursued because it is designed to answer questions that previous generations could only ask. How do we fit into the biological scheme of the cosmos? Is intelligent life a rare event or a common one in the universe? Can technological civilizations last for long periods of time, or do they inevitably self-destruct or die out for some other reason? If we could understand any signal that we detect, there’s always the possibility that we could be presented with enormously valuable knowledge. It is likely that any civilization we discover will be far more advanced than ours, and might help us to join a galactic network of intelligent beings. But even if we detect a signal without being able to understand it, that would still tell us that we are not unique in the universe. The effect on society might be as profound and long lasting as when Copernicus displaced the Earth from the center of our universe.   

What do other scientists think of the search for extraterrestrial civilizations?
Most scientists support the search. Here are some quotations from professional reviews: From the Report of the Astronomy Survey Committee, National Academy of Sciences, 1972: "... More and more scientists feel that contact with other civilizations is no longer something beyond our dreams but a natural event in the history of mankind that will perhaps occur in the lifetime of many of us ... In the long run, this may be one of science's most important and most profound contributions to mankind and to our civilization."

From the Report of the Astronomy Survey Committee, National Academy of Sciences, 1982: "... It is hard to imagine a more exciting astronomical discovery or one that would have greater impact on human perceptions than the detection of extraterrestrial intelligence."

From the Report of the Astronomy Survey Committee, National Academy of Sciences, 1991: "... The discovery in the last decade of planetary disks (around other stars), and the continuing discovery of highly complex organic molecules in the interstellar medium, lend even greater scientific support to this enterprise."

For more than forty years, SETI science has received the highest seal of approval available to astronomy-related science. Every ten years, the National Research Council of the National Academy of Sciences produces a decadal report of the priorities for astronomy and astrophysics. SETI has been repeatedly endorsed in each review. The most recent report (the reviews occur once every ten years), released in 2000 and covering the period 2000-2010, was particularly clear in its praise of the Allen Telescope Array and its potential, noting that "SETI research demands continued development of innovative technology and approaches, " and describing the ATA (at the time referred to as 1Ht) as … [the Allen Telescope Array] is "a good example of such an innovative approach," that "will pioneer new radio techniques."

The 2000 decadal review was particularly special noteworthy because it marked the first time that SETI had received the Academy's endorsement since SETI had moved from a federally funded to a privately funded enterprise. There has been no federal support for SETI since 1993, yet through the vision and support of thousands of supporters around the world, SETI science has advanced - not declined - as a privately funded endeavor. The non-profit SETI Institute is the international leader in SETI research and exploration, and having raised over $50 million of philanthropic support for SETI's endeavors since 1993.  

Do the recent discoveries of extrasolar planets and possible microfossils from Mars affect your research? Yes and no. It turns out that most of the stars discovered to have planetary systems were already on Project Phoenix's target list. It also confirms an early premise of SETI scientists -- namely that planets ought to form around a significant fraction of stars in our galaxy. The Mars meteorite finding is another potential confirmation that life is indeed common throughout the universe. In fact, some Institute scientists are involved in planning future NASA missions to Mars.

IV. SETI, Education and Public Outreach

How can I contact the SETI Institute?
The best way is to email us by using this form.

Does the SETI Institute have public events or tours?
Not often. There isn't actually that much to see. Remember, the telescopes are spread around the globe, and none is within a thousand miles of the Institute. Announcements of upcoming lectures and publications by SETI Institute personnel can be found elsewhere on this site. 

How can I get a job at the SETI Institute or with SETI in general?
The SETI Institute is not a large organization, and so hirings are infrequent. Since our search is conducted with radio telescopes, most of the skills involved are related to the fields of astronomy, biology, chemistry, physics, electrical engineering and computer science. There is also an administrative group. Before sending resumes, interested people should first contact the Institute about which jobs, if any, are open. Remember that Project Phoenix is only one of several dozen research efforts conducted under the aegis of the Institute.

What kind of education do I need to work in SETI?
Most SETI researchers and engineers have university degrees in electrical engineering or computer science. Quite a few have PhDs in astronomy or physics. The Institute's other projects employ scientists trained in biology, planetary science, and related fields.   

Can I become a member of the SETI Institute?
Yes! Learn more about the SETI Institute's dynamic new membership program, TeamSETI. Become part of the Team!
Many people have heard about the SETI@Home project as a way to participate in SETI. This project does not involve Project Phoenix directly, however several advisors to SETI@Home are staff members at the SETI Institute.

V. Related Information

Do you have any pictures of UFO's or aliens?

No. At this time, there is no compelling scientific evidence to support the idea that extraterrestrials are here or on their way. The reasons for this are detailed in our document entitled "Why the SETI Institute does no UFO Research". However, you may wish to reflect on the fact that if there were interesting, verifiable evidence that extraterrestrials were visiting our planet, tens of thousands of university scientists would be busy investigating this idea. They're not.