Astronomy

Would it have been possible to send a radio signal towards ʻOumuamua?

Would it have been possible to send a radio signal towards ʻOumuamua?


We are searching data for your request:

Forums and discussions:
Manuals and reference books:
Data from registers:
Wait the end of the search in all databases.
Upon completion, a link will appear to access the found materials.

As we could not get any radio signals from asteroid ʻOumuamua, couldn't we have sent a powerful radio signal to it and then check if we can get any radio signal in response?

This way we can at least check if it is just a rock or any alien spaceship. If it were an alien spacecraft, then they should definitely give a radio signal in response I believe.


Answer posted under the wire during closure. Others may be able to write an additional and/or different answer as soon as two more reopen votes are cast.

Would it have been possible to send a radio signal towards ʻOumuamua?

Yes. It is certainly true that at any time, a large radio telescope or even a small transmitter can always sent a signal toward something. New Horizons can receive our signals now even though it's in the Kuiper belt because it knows when and where to listen and at what frequency.

As we could not get any radio signals from asteroid ʻOumuamua, couldn't we have sent a powerful radio signal to it and then check if we can get any radio signal in response?

The asteroid was quite close to us in the 2nd half of 2017, but now it's much farther than New Horizons. However if it had advanced technology it would know we were very active in the electromagnetic radio spectrum and it might be listening. If so, we certainly could have sent it a signal that it could receive.

Checking for a response is also hard because we'd need to know what frequency and when. We'd have to allocate resources, etc.

For the frequency, see also


Below: Plots of the distance of ʻOumuamua (bumpy, blue) and the New Horizons spacecraft (straight, green) from Earth as a function of years since 2017-01-01.


Would it have been possible to send a radio signal towards ʻOumuamua? - Astronomy

I was just wondering if there are any unexplained or weakly theorized high-power activities (like Gamma Ray Bursts) that could possibly be caused by activity of other advanced civilizations in our universe? Forgive me, I know that the question is pretty "out there", it's just that I was wondering if anyone was looking for signs of extra-terrestrial life in this manner.

There's no way we can rule it out completely, of course. However, I think there are several reasons why this is probably not the case.

First, all the astronomical phenomena we see tend to be "broadband," which basically means that they emit light containing a lot of different colors. By contrast, many of the signals that humans produce that would be detectable from outer space are narrowband, meaning that the light contains primarily one specific color. This is especially true of signals used for communication—for example, when you listen to a radio station you have to tune your radio to a very specific frequency (i.e. "color" of the radio wave) in order to receive the signal that is being sent, and if you change it a bit you will no longer detect that station's broadcast.

Narrowband signals are the best way to concentrate as much of the signal power as possible into a detectable regime, which saves energy and makes it easier to discern the signal from background noise. So it is likely that extraterrestrial civilizations would also use narrowband signals to communicate, and none of the astronomical phenomena we have seen fall into this category (the [email protected] project, in fact, only searches for narrowband signals, and that's one of the ways they would be able to distinguish any "real" extraterrestrial signal from a naturally occurring phenomenon).

On the other hand, it's possible that extraterrestrial civilizations have receivers that work differently than ours do (so that their definition of "narrowband" would be different from ours), and it's certainly possible that they might produce signals not intended for communication that we would be able to detect.

Second, the astronomical phenomena we observe tend to be extremely energetic events, and it is difficult to imagine what an extraterrestrial civilization might be doing to use that much energy that quickly. Gamma Ray Bursts (GRBs) in particular are among the most energetic events in the universe, typically releasing around 10 51 ergs of energy in less than one minute—this is equivalent to taking a planet with the mass of Jupiter and completely converting its mass into energy (as in a nuclear bomb) in an extremely short period of time! Why extraterrestrial civilizations would want to make Jupiter-sized planets completely disappear and send the energy beaming off into the universe is a mystery to me (although I certainly can't claim to have any idea how they think).

Third, the astronomical phenomena that we see tend to fall into distinct categories, and within each category there are many different objects whose properties are the same, except for statistical fluctuations. For example, there have been thousands of GRBs discovered, and if you look at a histogram of their durations (how long each event lasts), you see that they cluster around a particular value with some statistical variation around that value (actually, in the case of GRBs there are two values with statistical variation around each, but that's because what we call "GRBs" are actually now thought to be two different types of objects).

This may be speculation, but I don't think advanced civilizations are so predictable that they would all evolve towards the point where they decided to do the same, extreme event (such as obliterate one of the planets in their solar system). I think we see evidence of this on Earth, where human beings who were initially isolated from each other developed such different cultures all around the world. To me, the fact that the different astronomical events we see are so similar all over the universe is evidence that they have a simple physical explanation, rather than being due to the activity of living creatures and their vastly more complex chemistry and behavioral patterns.

Interestingly enough, when the first radio pulsar was discovered in 1967, the idea was briefly considered that the periodic signal might have been from an alien civilization. As described by Jocelyn Bell (the graduate student who made the initial discovery), at first she was jokingly upset about the possibility ("Here was I trying to get a Ph.D. out of a new technique, and some silly lot of little green men had to choose my aerial and my frequency to communicate with us"), but once she discovered a second pulsar, she realized immediately that it was very unlikely to be the work of an extraterrestrial civilization. In her words: "I left the recording on Tony's desk and went off, much happier, for Christmas. It was very unlikely that two lots of little green men would both choose the same, improbable frequency, and the same time, to try signalling to the same planet Earth."

We now know that pulsars can be well-explained as rapidly rotating neutron stars, and since the initial discovery astronomers have found over a thousand more of these objects. I think it is very likely that any new categories of suspicious objects which are discovered in the future will follow a similar history as pulsars did.

This page was lasy updaed by Jake Turner on January 28, 2019.

About the Author

Dave Rothstein

Dave is a former graduate student and postdoctoral researcher at Cornell who used infrared and X-ray observations and theoretical computer models to study accreting black holes in our Galaxy. He also did most of the development for the former version of the site.


Astronomers Will Be Able to Use the World’s Biggest Radio Telescope to Search for Signals from Extraterrestrial Civilizations

Back in April, we reported on how a collaboration between the Chinese Academy of Sciences, the Breakthrough Listen Initiative, and the SETI Institute planned to use the new Five-hundred-meter Aperture radio Telescope (FAST) to search for signs of extraterrestrial life. We now caught up with another of the project scientists to flesh out some more details of their observational plans and what observations they hope to make in the future.

FAST took in its first light in 2016, and was fully commissioned in January of 2020, but the project has been used exclusively by local Chinese scientists so far. That is about to change in the coming year, and many groups, including those interested in SETI are ready to submit proposed observational plans that would make use of FAST’s extraordinarily high sensitivity, which is 2.5x more than the next best radio telescope available.

There are three prongs to the observational plans the authors of the paper published in Research in Astronomy and Astrophysics suggest. First, they will look at the Andromeda galaxy, then at stars shown by TESS to have planets in their potentially habitable zone, and finally to take a look at modulated signals that have been undetectable to SETI efforts until recently.

Depiction of the observatories being used by the Breakthrough Listen Initiative
Credit: Breakthrough Listen

The first of these targets, the Andromeda galaxy, might seem like a strange choice for a SETI monitoring mission. However, Dr. Vishal Gajjar, a scientist with the Breakthrough Listen Initiative and corresponding author on the paper, points out that so far astronomers have completely ignored any potential signals coming from the galaxy.

This might be because many signals would be considered too weak to be detectable by modern instruments. However, with the increased sensitivity of FAST, astronomers would be able to pick up signals at 10 19 watts. That might seem like alot of power – it is more than the entire Earth’s annual consumption. However, for large scale civilizations, such as those that might be considered Kardashev Type II, it would barely be a drop in the bucket. So there is a decent chance that we would be able to pick up a signal from such a civilization even as far away as Andromeda.

Image showing how the Andromeda galaxy can be broken down into honeycombs, which can then be the focus of on of FAST’s 19 imaging beams.
Credit: D Li. et all

Our closest neighboring galaxy itself is composed of 1 trillion stars, which would be a lot to search through. Luckily, FAST has a unique feature that would make it well suited to observe such a densely packed area. It has 19 individual beams that can be directed at different points in the sky. The team plans to survey the more than 1 trillion stars in the Andromeda galaxy by taking 21 hexagonal images, each will require 4 different pointings of the 19 beams that make up FAST’s data collection system. Each pointing would take 10 minutes, so the entire survey of the Andromeda galaxy would only take around 14 hours of observing time.

That would leave plenty of extra time for another of the surveys the team hopes to accomplish – a survey of planets in the habitable zone of their star found by the Transiting Exoplanet Survey Satellite (TESS). While Kepler, another planet hunting telescope, has actually found more exoplanets than TESS, most of them are much farther away, and therefore would have much weaker signals. The average distance to a planet that TESS surveyed is between 100-200 light years – much closer than those found by Kepler. So even if a civilization there wasn’t intentionally sending a signal straight at Earth, we may be able to catch fleeting glimpses of messages they would send among themselves, such as controlling robotic rovers on another planet or emitting their equivalent of radio frequency television channels.

Artist concept of the Transiting Exoplanet Survey Satellite and its 4 telescopes.
Credit: NASA/MIT

Instead of using the Fast L-band Array (FLAN), which hosts the 19 beams that would be so useful in studying Andromeda, the team plans to use a series of single beam receivers to study the TESS candidate planets. These single beam receivers have a much wider bandwidth than the 1050-1450 band that is available on FLAN. They range from A1 (70-140 MHz) to A1 (2000-3000 MHz). The spectral width of these receivers will allow astronomers to look at signals that would be unreachable using other telescopes. Aliens could potentially use unconventional signal bandwidths, so the larger frequency size a telescope is able to capture, the more valuable it is to SETI astronomers.

It is not only repeating signals on a single bandwidth that interest those astronomers. Modulated signals, such as those that carry data, would be a holy grail of SETI research. With a combination of FAST’s sensitivity and some new AI assisted machine learning algorithms, researchers will finally be able to identify a modulated signal of unknown origin.

The Breakthrough Listen team joined the US Army’s Artificial Intelligence Signal Classification challenge. As part of that challenge, they developed an algorithm known as a machine learning classifier that was able to identify novel modulated signals with 95% accuracy. When applied to SETI, this would help the team notice any type of novel modulated pattern. As with signal bandwidths, aliens might use a completely unknown modulation technique. But the Breakthrough Listen team’s algorithm should be able to identify that there is a signal at least. Translating what it means is best left to science fiction books like Contact for now.

Examples of different types of modulation – Frequency Modulation (FM) and Amplitude Modulation (AM). Both are commonly used in consumer stereo equipment
Credit: NASA /’ JPL

In the future such a translation program might be possible – scientists are smart after all. Any such effort would require an enormous amount of collected data. For now, FAST is still the best quality data source available for such SETI searches. The Breakthrough Listen team hopes to receive funding for the search programs described in their paper in the next few years. They are already working with a FAST project scientist from Beijing Normal University for some small observational tasks. Recently that team was approved to use the FAST telescopes for 14 hours for a SETI project. The largest observations, such as Andromeda and the TESS planets, are still about a year away.

Dr Gajjar expressed the team’s enthusiasm for working with FAST, stating they are “looking forward to conducting some of the deepest radio studies anyone has ever done before.” And they have even more to look forward to. The Breakthrough Listen team is already engaged with MeerKAT, a telescope back in South Africa that recently received an updated computing cluster that will allow the team to perform some advanced frequency computations that have never been possible before. And the entire MeerKAT system is a precursor to the Square Kilometer Array, which promises to turn impact the entire field of radio astronomy when it comes online around 2027. Until then, FAST will prove an invaluable tool that will allow SETI and all other kinds of radio astronomy researchers to collect more data and draw better conclusions.


Would it have been possible to send a radio signal towards ʻOumuamua? - Astronomy

I was just wondering if there are any unexplained or weakly theorized high-power activities (like Gamma Ray Bursts) that could possibly be caused by activity of other advanced civilizations in our universe? Forgive me, I know that the question is pretty "out there", it's just that I was wondering if anyone was looking for signs of extra-terrestrial life in this manner.

There's no way we can rule it out completely, of course. However, I think there are several reasons why this is probably not the case.

First, all the astronomical phenomena we see tend to be "broadband," which basically means that they emit light containing a lot of different colors. By contrast, many of the signals that humans produce that would be detectable from outer space are narrowband, meaning that the light contains primarily one specific color. This is especially true of signals used for communication—for example, when you listen to a radio station you have to tune your radio to a very specific frequency (i.e. "color" of the radio wave) in order to receive the signal that is being sent, and if you change it a bit you will no longer detect that station's broadcast.

Narrowband signals are the best way to concentrate as much of the signal power as possible into a detectable regime, which saves energy and makes it easier to discern the signal from background noise. So it is likely that extraterrestrial civilizations would also use narrowband signals to communicate, and none of the astronomical phenomena we have seen fall into this category (the [email protected] project, in fact, only searches for narrowband signals, and that's one of the ways they would be able to distinguish any "real" extraterrestrial signal from a naturally occurring phenomenon).

On the other hand, it's possible that extraterrestrial civilizations have receivers that work differently than ours do (so that their definition of "narrowband" would be different from ours), and it's certainly possible that they might produce signals not intended for communication that we would be able to detect.

Second, the astronomical phenomena we observe tend to be extremely energetic events, and it is difficult to imagine what an extraterrestrial civilization might be doing to use that much energy that quickly. Gamma Ray Bursts (GRBs) in particular are among the most energetic events in the universe, typically releasing around 10 51 ergs of energy in less than one minute—this is equivalent to taking a planet with the mass of Jupiter and completely converting its mass into energy (as in a nuclear bomb) in an extremely short period of time! Why extraterrestrial civilizations would want to make Jupiter-sized planets completely disappear and send the energy beaming off into the universe is a mystery to me (although I certainly can't claim to have any idea how they think).

Third, the astronomical phenomena that we see tend to fall into distinct categories, and within each category there are many different objects whose properties are the same, except for statistical fluctuations. For example, there have been thousands of GRBs discovered, and if you look at a histogram of their durations (how long each event lasts), you see that they cluster around a particular value with some statistical variation around that value (actually, in the case of GRBs there are two values with statistical variation around each, but that's because what we call "GRBs" are actually now thought to be two different types of objects).

This may be speculation, but I don't think advanced civilizations are so predictable that they would all evolve towards the point where they decided to do the same, extreme event (such as obliterate one of the planets in their solar system). I think we see evidence of this on Earth, where human beings who were initially isolated from each other developed such different cultures all around the world. To me, the fact that the different astronomical events we see are so similar all over the universe is evidence that they have a simple physical explanation, rather than being due to the activity of living creatures and their vastly more complex chemistry and behavioral patterns.

Interestingly enough, when the first radio pulsar was discovered in 1967, the idea was briefly considered that the periodic signal might have been from an alien civilization. As described by Jocelyn Bell (the graduate student who made the initial discovery), at first she was jokingly upset about the possibility ("Here was I trying to get a Ph.D. out of a new technique, and some silly lot of little green men had to choose my aerial and my frequency to communicate with us"), but once she discovered a second pulsar, she realized immediately that it was very unlikely to be the work of an extraterrestrial civilization. In her words: "I left the recording on Tony's desk and went off, much happier, for Christmas. It was very unlikely that two lots of little green men would both choose the same, improbable frequency, and the same time, to try signalling to the same planet Earth."

We now know that pulsars can be well-explained as rapidly rotating neutron stars, and since the initial discovery astronomers have found over a thousand more of these objects. I think it is very likely that any new categories of suspicious objects which are discovered in the future will follow a similar history as pulsars did.

This page was lasy updaed by Jake Turner on January 28, 2019.

About the Author

Dave Rothstein

Dave is a former graduate student and postdoctoral researcher at Cornell who used infrared and X-ray observations and theoretical computer models to study accreting black holes in our Galaxy. He also did most of the development for the former version of the site.


We're no strangers to 'alien' false alarms – one was caused by a microwave oven

The group of Russian astronomers spotted something unusual. They were observing the rather innocuous star HD 164595, located in the constellation of Hercules 94 light years (or about 900 trillion kilometres) from Earth. It's a sun-like star of a similar age to the Sun and is known to have at least one large planet orbiting it. So it was with some surprise that the astronomers at the RATAN-600 radio telescope, located in Zelenchukskaya and led by Nikolay Bursov, received a short but loud radio burst from the direction of HD 164595.

News of the signal broke in mid August this year – even though it was originally picked up on May 15 2015. Given the possible origin of the radio signal, its frequency, and the signal strength there has been much speculation about what the source could be, including the possibility that it is a beacon signal from an advanced alien civilisation.

Such a short duration and bright radio burst is difficult to explain as a naturally occurring, if it is at the distances suggested by the direction it came from. The strength of the signal was 0.75 Janskys, which might not seem much given that a mobile phone at a distance of a kilometre has a signal strength of 110m Janskys. But at the distances involved (if it is coming from HD 164595) it is a very powerful signal indeed.

In response to the announcement, the Search for Extra-Terrestrial Intelligence (SETI) and Messaging to Extra-Terrestrial Intelligence (METI) institutes are turning the Allen Telescope Array and the Boquete Optical SETI Observatory towards the star. They hope that if this bank of radio telescopes built in part to look for alien life can recover the signal, they can learn more about its nature and origin.

The RATAN-600 radio telescope. Credit: Konstantin Malanchev/Flickr, CC BY

Too powerful for aliens?

So is the mysterious signal likely to be a message from space? If it is a beacon signal, sent in all directions, the transmitter would need a hundred million trillion watts of power. This power consumption is about a hundred million times the entire energy output of all the power stations on Earth.

The power requirement could be reduced quite a lot by pointing the beam at the Earth, rather than broadcasting in all directions. This would reduce the power needed to just about the entire Earth's output. However, at a distance of 94 light years, the radio signal from HD 164595 would have to have been sent years before the source received any of the radio signals that leak out into space from the Earth. Which raises the question why any alien civilisations would have targeted our planet.

The frequency that the HD 164595 signal was detected is in the military wave band and not at a frequency we would expect a "Hello" signal to be. We would expect such a signal to be broadcast at a frequency with little noise that astronomers, alien or human, would be using such as the 21cm hydrogen frequency. The detected frequency of the transmission and its strength mean it is more likely a military signal that has bounced off some space debris and into the Russian observatory than an alien signal from deep space. A local source such as this would explain both the short duration and the intensity of the signal. It is also telling that in the previous thirty-eight HD 164595 observations, no trace of any radio signal has been seen.

False detections have been made before. The most recent signal was found to be caused by a kitchen microwave being opened while it was still running. In the 1960s, the first pulsar was mistaken for an extra-terrestrial beacon, and even named Little Green Men 1, before being recognised as a rapidly rotating core of a dead star.

However, not all SETI signals have been explained. The most famous, the WOW signal of 1977, was both brighter and longer than the 15th May signal. And despite follow up observations, the WOW signal was never observed again and remains largely unexplained. Likewise, KIC 8462852, a star in the constellation of Cygnus, that appears to be changing in brightness in a strange way that currently cannot reasonably be explained. It might even be a mega structure being built around the star by an advanced civilisation.

Perhaps the most important thing that comes out of the HD 164595 signal is that there is still a lot of things out there we don't yet understand and we need to keep looking.

"Mark is a professional astronomer, author and science educator working in the School of Physics Astronomy and Mathematics at the University of Hertfordshire where he holds the Ogden Fellowship. He is actively involved in the University's extensive public engagement and school education programme."

This article was originally published on The Conversation. Read the original article.


METI to Send Signal to Proxima b

By now you’ve probably heard of SETI, or the ‘Search for Extraterrestrial Intelligence’, which is a research organization that tunes and monitors receivers to look for any alien radio signals or transmissions. Instead of waiting for ET to contact Earth, however, a group known as METI, or Messages to Extraterrestrial Intelligence, intends to take a more prominent and proactive role in the search for alien life by being the ones to actually transmit contact messages into space.

Former director of Interstellar Message Composition at the SETI Institute, Douglas Vakoch, is propelling the METI Initiative forward with a single planet in mind: a recently discovered one that at 4.2 light-years distant is the closest exoplanet to the Earth. It orbits around Proxima Centauri, the closest star apart from the Sun, and while Vakoch notes that METI has a few other planets in mind, he also point out a number of advantages to specifically exploring Proxima Centauri b. Chief amongst those is the need to keep the signal’s travel time as short as possible, as well as the fact it’s been suggested that this exoplanet could potentially host life.

Programs similar to METI have been attempted in the past, most notably including the Arecibo radio message that was sent in 1974 to the Hercules Globular Cluster (M13), which is located 21,000 light-years distant and contains more than 300,000 individual stars. Carl Sagan, Frank Drake, and company beamed the powerful uncoded message in an easily understood format consisting of simple graphics and scientific facts in the hopes of exposing our existence to extraterrestrial neighbors. For such a message to be understood, it was composed in a universal language, or more specifically the language of mathematics, because if otherworldly civilizations exist and are sending or looking for signals, they must at least know the basics of mathematics.

While some believe that its humanity’s ultimate destiny to join the galactic club, others, including Stephen Hawking, are more wary of the subject and fear it could spark an alien invasion should we make contact. While some members of the SETI community have expressed their beliefs that any attempted contact should be approached with caution, Andrew Fraknoi, astronomy professor at Foothill College, has stated that going out on a limb to make contact makes sense, noting that “if everyone decides only to receive messages, it will be a very quiet galaxy.”

In the meantime, Vokoch thinks that our presence is already likely known to alien life, and that any intelligent civilization that has the ability to travel in space will already know of our existence due to the space noise created by our accidental radio and TV signals.

This year, METI intends to use a facility located in Boquete, Panama, to search for signals coming from Proxima b, with the organization’s goal being to show other intelligent civilizations in the universe that we are actively and purposefully trying to establish contact.


Would it have been possible to send a radio signal towards ʻOumuamua? - Astronomy

I was just wondering if there are any unexplained or weakly theorized high-power activities (like Gamma Ray Bursts) that could possibly be caused by activity of other advanced civilizations in our universe? Forgive me, I know that the question is pretty "out there", it's just that I was wondering if anyone was looking for signs of extra-terrestrial life in this manner.

There's no way we can rule it out completely, of course. However, I think there are several reasons why this is probably not the case.

First, all the astronomical phenomena we see tend to be "broadband," which basically means that they emit light containing a lot of different colors. By contrast, many of the signals that humans produce that would be detectable from outer space are narrowband, meaning that the light contains primarily one specific color. This is especially true of signals used for communication—for example, when you listen to a radio station you have to tune your radio to a very specific frequency (i.e. "color" of the radio wave) in order to receive the signal that is being sent, and if you change it a bit you will no longer detect that station's broadcast.

Narrowband signals are the best way to concentrate as much of the signal power as possible into a detectable regime, which saves energy and makes it easier to discern the signal from background noise. So it is likely that extraterrestrial civilizations would also use narrowband signals to communicate, and none of the astronomical phenomena we have seen fall into this category (the [email protected] project, in fact, only searches for narrowband signals, and that's one of the ways they would be able to distinguish any "real" extraterrestrial signal from a naturally occurring phenomenon).

On the other hand, it's possible that extraterrestrial civilizations have receivers that work differently than ours do (so that their definition of "narrowband" would be different from ours), and it's certainly possible that they might produce signals not intended for communication that we would be able to detect.

Second, the astronomical phenomena we observe tend to be extremely energetic events, and it is difficult to imagine what an extraterrestrial civilization might be doing to use that much energy that quickly. Gamma Ray Bursts (GRBs) in particular are among the most energetic events in the universe, typically releasing around 10 51 ergs of energy in less than one minute—this is equivalent to taking a planet with the mass of Jupiter and completely converting its mass into energy (as in a nuclear bomb) in an extremely short period of time! Why extraterrestrial civilizations would want to make Jupiter-sized planets completely disappear and send the energy beaming off into the universe is a mystery to me (although I certainly can't claim to have any idea how they think).

Third, the astronomical phenomena that we see tend to fall into distinct categories, and within each category there are many different objects whose properties are the same, except for statistical fluctuations. For example, there have been thousands of GRBs discovered, and if you look at a histogram of their durations (how long each event lasts), you see that they cluster around a particular value with some statistical variation around that value (actually, in the case of GRBs there are two values with statistical variation around each, but that's because what we call "GRBs" are actually now thought to be two different types of objects).

This may be speculation, but I don't think advanced civilizations are so predictable that they would all evolve towards the point where they decided to do the same, extreme event (such as obliterate one of the planets in their solar system). I think we see evidence of this on Earth, where human beings who were initially isolated from each other developed such different cultures all around the world. To me, the fact that the different astronomical events we see are so similar all over the universe is evidence that they have a simple physical explanation, rather than being due to the activity of living creatures and their vastly more complex chemistry and behavioral patterns.

Interestingly enough, when the first radio pulsar was discovered in 1967, the idea was briefly considered that the periodic signal might have been from an alien civilization. As described by Jocelyn Bell (the graduate student who made the initial discovery), at first she was jokingly upset about the possibility ("Here was I trying to get a Ph.D. out of a new technique, and some silly lot of little green men had to choose my aerial and my frequency to communicate with us"), but once she discovered a second pulsar, she realized immediately that it was very unlikely to be the work of an extraterrestrial civilization. In her words: "I left the recording on Tony's desk and went off, much happier, for Christmas. It was very unlikely that two lots of little green men would both choose the same, improbable frequency, and the same time, to try signalling to the same planet Earth."

We now know that pulsars can be well-explained as rapidly rotating neutron stars, and since the initial discovery astronomers have found over a thousand more of these objects. I think it is very likely that any new categories of suspicious objects which are discovered in the future will follow a similar history as pulsars did.

This page was lasy updaed by Jake Turner on January 28, 2019.

About the Author

Dave Rothstein

Dave is a former graduate student and postdoctoral researcher at Cornell who used infrared and X-ray observations and theoretical computer models to study accreting black holes in our Galaxy. He also did most of the development for the former version of the site.


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

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.

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.


Mysterious radio signal is coming from inside our galaxy, scientists announce

Mysterious, intense blasts of radio energy have been detected from within our own galaxy, astronomers have said.

Fast radio bursts, or FRBs, last only a fraction of a second but can be 100 million times more powerful than the Sun. Despite their intensity, their origin remains largely unknown.

Now astronomers have been able to observe a fast radio burst in our own Milky Way, for the first ever time. As well as being closer than any FRB ever detected before, they could finally help solve the mystery of where they come from.

Scientists have had trouble tracking down the origin of such blasts because they are so short, unpredictable and originate far away. It is clear that they must be formed in some of the most extreme conditions possible in the universe, with suggested explanations including everything from dying stars to alien technology.

The bursts of radio energy appear to have come from a magnetar, or a star with a very powerful magnetic field, the scientists who discovered the new FRBs said. They were able to confirm that the blast would look like the other, more distant FRBs if it was observed from outside of our own galaxy – suggesting that at least some of the other blasts could be formed by similar objects elsewhere, too.

Recommended

“There’s this great mystery as to what would produce these great outbursts of energy, which until now we’ve seen coming from halfway across the universe,” said Kiyoshi Masui, assistant professor of physics at MIT, who led the team’s analysis of the FRB’s brightness. “This is the first time we’ve been able to tie one of these exotic fast radio bursts to a single astrophysical object.”

The detection began on 27 April, when researchers using two space telescopes picked up multiple X-ray and gamma-ray emissions coming from a magnetar at the other end of our galaxy. The next day, researchers used to two North American telescopes to observe that patch of sky, and picked up the blast that came to be known as FRB 200428.

As well as being the first FRB from the Milky Way and the first to be associated with a magnetar, the blast is the first to send out emissions other than radio waves.

The research is described in three papers published in the journal Nature today. It relied on data taken from telescopes around the world, with an international team of scientists using observations taken from equipment in Canada, the US, China and space.

FRBs were first discovered in 2007, immediately prompting a flurry of speculation on what could be able to cause such intense blasts of energy. Magnetars have emerged as the most likely candidate, especially given theoretical work that suggests their magnetic fields could work like engines, driving the powerful blasts.

To test that, astronomers have attempted to place the origin of the bursts within as small parts of the sky as possible. In theory, that should allow them to associate them with known objects in space, and look for associations between the bursts of radio energy and other astronomical phenomena.

The new study is the first to do that work and to provide evidence linking the FRBs with magnetars. At the very least, that could be a valuable clue to the origin of at least some of those FRBs.

"We calculated that such an intense burst coming from another galaxy would be indistinguishable from some fast radio bursts, so this really gives weight to the theory suggesting that magnetars could be behind at least some FRBs," said Pragya Chawla, one of the co-authors on the study and a senior PhD student in the Physics Department at McGill.

The new findings may still not explain all of the known FRBs "given the large gaps in energetics and activity between the brightest and most active FRB sources and what is observed for magnetars, perhaps younger, more energetic and active magnetars are needed to explain all FRB observations," said Paul Scholz, from the Dunlap Institute of Astronomy and Astrophysics at the University of Toronto.

If the FRB can be proven to have come from a magnetar, many mysteries still remain. Astronomers will need to look for the mechanism that allows the magnetar to power an FRB, looking for instance to understand how it could send out such bright, unusual bursts of energy and X-ray emissions at the same time.


A big yet brief interstellar voyager

Researchers discovered 'Oumuamua on October 18.

After further telescope observations, astronomers described it as an unusually oblong asteroid with dense, metal-rich rock. It also has a dark-red sheen — a color it earned from billions of years of cosmic rays corroding organic molecules on its surface — and, while it zips through the solar system at more than 16 miles per second, is tumbling wildly, rather than rotating smoothly.

Breakthrough Listen began a first round of observations with the Green Bank Telescope in West Virginia at 'Oumuamua on Wednesday afternoon. (The device "listens" in radiowaves, so observations at night aren't required.)

During the first pass, the Green Bank Telescope aimed its antennas at 'Oumuamua and listened to billions of wireless radio channels for two hours. According to Breakthrough Listen, this observation recorded a whopping 90 terabytes of raw data — enough to fill up 23 new top-of-the-line iMac Pro computers.

"So far, no signal was detected," Avi Loeb, a physicist at Harvard University and a member of Breakthrough Listen's leadership, told Business Insider on Thursday.

"During follow-up observations the coming week, we will do 3 more passes with each receiver to cover other phases of Oumumua's [sic] rotation," Siemion wrote in an email that Loeb forwarded to Business Insider.

As for that strange cigar shape, Loeb suspects there is a simple yet surprising explanation, though he emphasized his lack of a definitive answer.

"I am currently working on ideas for how to form a highly elongated shape for a rock through a natural process," Loeb said. "One path is through spin of molten rock droplets (lava) that form in collision of rocky planets (similar to the collision that produced the moon out of the Earth). Another is through instabilities in dust forming environments."


Watch the video: EXPLAINED! I have LIVED v I have been LIVING. Present Perfect v Present Perfect Continuous (May 2022).