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`Oumuamua: Listening To An Interstellar Interloper

The buzz about `Oumuamua, our first known visitor from another stellar system, seems likely to continue given yesterday’s news that the object’s axis ratio is a startling 10 to 1. Given all that, Jim Benford wondered whether there were SETI implications here. Was anyone on the case from our major SETI organizations? The answer is below, as we learn that the effort is ongoing. A frequent contributor to these pages, Jim is President of Microwave Sciences in Lafayette, California, which deals with high power microwave systems from conceptual designs to hardware. He also heads up the critical sail subcommittee for Breakthrough Starshot, the effort to send small beamed sails with miniaturized payloads to a nearby star.

By James Benford

I contacted Jill Tarter and Andrew Siemion about whether SETI researchers are conducting observations of the interstellar interloper, Oumuamua. Both say yes.

Jill said that the Allen Telescope Array has been looking at it for a while. Andrew said that Breakthrough Listen was using the Green Bank Telescope for a few hours last weekend. This was actually looking for water via hydroxyl lines using broadband 1.1-1.9 GHz data. No water was immediately evident in the coarse spectra from the standard data reduction. Breakthrough Listen is working on incorporating the appropriate windowing capabilities necessary to analyze this data, so as to use their data analysis pipeline.

Therefore there are some observations in parts of the microwave spectrum.

Image: This diagram shows the orbit of the interstellar asteroid ‘Oumuamua as it passes through the Solar System. Unlike all other asteroids and comets observed before, this body is not bound by gravity to the Sun. It has come from interstellar space and will return there after its brief encounter with our star system. Its hyperbolic orbit is highly inclined and it does not appear to have come close to any other Solar System body on its way in. Credit: ESO/K. Meech et al.

Besides astronomical observations of this unique object, there is also this remote possibility: That this interloper is an interstellar survey probe, having perhaps dropped down to interplanetary-scale velocities in order to take data during its transit of our solar system, before going on to another star.

If this is the case, then perhaps we ought to be looking rather broadly in the electromagnetic spectrum for any signal it might send to us, having easily detected leakage from Earth. That assumes it would try to respond to us using frequencies it knows we use. That would certainly include the microwave bands 1-10 GHz, where most of our radiation leakage radiation is.

I think at present the frequencies most observable coming from Earth are leakage of uplink transmissions to our satellites, of which there are now about 1200 active in orbit. Those frequencies tend to be in the upper end of the microwave where the wavelength is smaller, so we can use smaller apertures on both Earth and satellite. Downlinks, of course, would be absorbed in the Earth and not observable from afar.

Or, because they know enough about our atmosphere’s transmission windows and the Sun’s radiation spectrum, they might be signaling in the visible. Therefore our SETI optical observatories ought to be watching as well.

I would look for a pulsed beacon signal, which is more noticeable. That would be like a pulsar, but of course with no interstellar dispersion.

This matter has a very low probability of success, of course. However, it’s our first opportunity to observe at close range a truly interstellar object.

Image: This plot shows how the interstellar asteroid `Oumuamua varied in brightness during three days in October 2017. The large range of brightness — about a factor of ten (2.5 magnitudes) — is due to the very elongated shape of this unique object, which rotates every 7.3 hours. The different coloured dots represent measurements through different filters, covering the visible and near-infrared part of the spectrum. The dotted line shows the light curve expected if `Oumuamua were an ellipsoid with a 1:10 aspect ratio, the deviations from this line are probably due to irregularities in the object’s shape or surface albedo. Credit: ESO/K. Meech et al.


Comments on this entry are closed.

  • Keith Mansfield November 22, 2017, 9:41

    An intriguing piece and the same, unlikely thought had of course crossed my mind. You talk about using pulsed visible light for communication. My reading of the Nature Abstract (don’t have full access) is that the bizarre proportions are due entirely to the measurement of the light curve.

    If that is the case and if there is no secondary confirmation of the 10:1 ratio, could it not be the case that this is a misinterpretation and Oumuamua is of a different shape and has actually been signalling?

  • Michael Fidler November 22, 2017, 10:20

    Wondering what an object of this size traveling at .20 the speed of light would emit in EM radiation with different types of breaking methods.
    Could we look for indications of this in wide field telescopes monitoring the sky’s or even amateur long exposure imagery of the heavens. What about hyper-drives or even wormholes, all of these should emit radiation from the radio frequencies to cosmic rays or maybe even weak gravity waves. Tracing its path back in time would tell where to look and in what time frame. How long would this radiation be emitted is another question, seconds, minutes even days to slow itself down to the speed that it past by earth. I keep thinking of the white holes that where all the vogue in the seventies.

    See if it is transmitting a signal in the soft X-rays around 1 nm.

    Interstellar communication. IV. Benchmarking information carriers.


    • Michael Fidler November 22, 2017, 10:32

      Is there any way to tell what directions the axises of rotation are pointing towards and are they precessing?

      • Michael Fidler November 22, 2017, 11:08

        Interesting that there seems to be a slow uptake of the brightness of `Oumuamua on the plot from October 25 after 2:24 UT just as it passes its lowest magnitude. You can see it again on October 27 after 2:24 UT and 5:30 UT and 9:36 UT.

        • DJ Kaplan November 22, 2017, 13:23

          Is it really going at 0.20 the speed of light?

          • AF November 22, 2017, 14:25

            No. It was at 0.2 AU at the closest approach to earth. It top speed was 87.7 km/s or 0.00029 of the speed of light.


    • Patrick Underwood November 22, 2017, 13:49

      This is sort of what I suggested in reply to the previous story. Look at recorded data from radio and optical telescopes pointed in the right direction in the weeks, months or years before the detection, for anything odd. Also any experiments detecting high energy particles.

      And now I go off the ranch. You know those mysterious booms being heard worldwide? Coincidence?? ;) Sure sounds like the beginning of a Benford novel to me. :)

      • Michael Fidler November 22, 2017, 20:14

        Some interesting chatter on Twitter on AstroWright:

        Is 1I/’Oumuamua an Alien Spacecraft?


      • Michael Fidler November 28, 2017, 2:43

        Magneto-hydrodynamic (MHD) – A craft flying past the Sun could use the Suns ionized corona to brake the spacecraft. The craft would have a very strong external MHD magnetic field when in operation. This should cause the splitting spectral lines due to the Zeeman effect and possibly the Stark effect. Of course now it would not be visible but if it is using a fluctuating field it may still show up as polarization of the light coming from the craft.

        This is very reminiscent of the huge cigar shaped mother-ships that were observed during the 1954 French wave.

  • Andrei November 22, 2017, 11:03

    Look for a signal from a rock?
    See comment by study coauthor Jayadev Rajagopal :
    “The most remarkable thing about U1 is that, except for its shape, how familiar and physically unremarkable it is.”

    • ljk November 22, 2017, 11:23

      I probably should not make jokes like this on the Internet, but perhaps that is exactly how “they” want to look, like an ordinary rock.

      So why is this fellow saying ‘Oumuamua is “familiar and physically unremarkable” yet so many others of his profession are saying it is anything but ordinary? What am I missing here?

      • DJ Kaplan November 22, 2017, 13:25

        We don’t know that it looks like a rock or that it doesn’t look like a rock. Science must assume that it’s a rock, and around this all future assumptions are attached, like Christmas ornaments.

      • hiro November 22, 2017, 19:18

        Close, but no cigar for you, especially a reddish one.

        • ljk November 28, 2017, 9:40

          Sometimes a cigar is just an alien probe trying to disguise itself as an ordinary space rock so it won’t have to socialize with the talking primates with car keys occupying Sol 3.

    • Marshall Eubanks November 22, 2017, 15:43

      With all due respect, that is not a very profound statement. What do we actually know about 1I? Its orbit, its shape (not yet its size), its rotation period and the fact that its spectrum is reddish. That’s 4 actual facts – plus another, negative one – there is no sign of any cometary activity.

      So, of these 5 pieces of information, #s 1 and 2 are unprecedented, #3 is (taken with # 2) unusual, and #5 was certainly unexpected, and thus remarkable in its own fashion. Of all of this, only number 4 is “unremarkable.” So, I guess, yes, if we ignore almost everything we know about 1I, it is indeed unremarkable.

      • Hanilton1 November 22, 2017, 19:56

        Mr Eubanks, I lurk around the mpml and expected a flurry of activity over the last 24 hours. But instead it has been completely silent about this light curve. Can you explain?

  • Alex Tolley November 22, 2017, 12:46

    Can someone point to a paper where light curves are compared to ground truth for known asteroids, like Itokawa?

    • Paul Gilster November 22, 2017, 12:55

      Now that’s a good idea!

    • Marshall Eubanks November 22, 2017, 16:01

      What do you mean by ground truth here? There is a whole MPC database devoted to asteroid light curves –


      and you can browse it to your heart’s content. (Well, except for 1I, which generates an SQL error due to the initial ‘.)

      More importantly, to me at least, the people who do this all of the time are comfortable with a 6:1:1 aspect ratio* based on the data published, but not (yet?) a 10:1:1 one. This object is getting a huge amount of attention, and the amount of real time peer review is about as good as it ever gets.

      * That assumes that we are in the 1I rotation plane. As that is likely not to be the case, the actual aspect ration is likely to be a somewhat larger.

      • Alex Tolley November 22, 2017, 22:53

        Marshall, thank you for the link to the light curves DB. Saved me a comment to your FB post.

        Here is the asteroid 25143 Itokawa:

        Here is the light curve:

        Even with a lot more light curves collected from the asteroid, could one reconstruct the basic shape of the asteroid where the image[s] is the “ground truth” of the asteroid’s shape?

        I could imagine that a computer could generate a lot of possible shapes for asteroids, illuminate the models and assume constant surface reflectivity to create a huge library of theoretical light curves that could be searched for best fit with any light curve to provide a small selection of possible shapes. The library would be rather large however, so perhaps a better strategy is to assume an ovoid and then iteratively tweak the shape using rules about the deviations to improve the fit between the modeled light curve and the experimentally determined one.

        Is anything like that being done?

    • Robert Miles December 4, 2017, 0:49

      You may be interested in a BOINC project for finding the rotation periods (and possibly also the light curves) for asteroids.



  • Alex Tolley November 22, 2017, 12:57

    Regarding signals. Wouldn’t a probe be silent for the same reasons the anti-METI folks want us to remain silent and not shout “yahoo” to the stars? While I think the probability is extremely low that this is an artificial object, the absence of communication is not proof of natural, not artificial, origin. A scouting probe would be expected to remain covert.

    Clarke’s original Rendezvous with Rama novel had a silent Rama that required close inspection to determine its nature. Without inspection, Rama’s nature would only have been indicated by its non-natural trajectory.

    `Oumuamua’s trajectory so far seems entirely natural, but again, a covert probe, even if it could alter its trajectory, wouldn’t.

    • DJ Kaplan November 22, 2017, 13:26

      If it’s a Bracewell probe, its priority might be to signal back to wherever it came from and not to us.

      • ljk November 22, 2017, 17:36

        Would an advanced ETI need to send a probe to other star systems to determine if they have intelligent life or not? There are a number of ways they could tell without having to leave their home system. Even we humans have several methods for remote detection and within a few decades we could have space telescopes that could image continents on Earthlike exoworlds.

        I am not saying they could not send a probe and may have numerous reasons for doing so, but if you just want to find out if a civilization exists on a distant world, you can do it without having to travel all the way there.

        Okay, it’s a survey probe for the Encyclopedia Galactica making its latest update rounds of the Milky Way.

        • DJ Kaplan November 22, 2017, 18:19

          Well, personally, I’m not in the business of second-guessing the thought processes of whatever alien lifeforms are crawling around there in the void.

          • Ljk November 24, 2017, 14:15

            Well what fun is that then?

        • Stan November 22, 2017, 20:46

          Of course if you want up to date data, you would have to get closer.
          Personally I’m betting it part of a planetary crust that was sheared off.

          • Dave November 23, 2017, 11:33

            That’s horrifying.

            • Harry R Ray December 11, 2017, 20:13

              AND COULD VERY WELL BE THE CASE!!!!! ArXiv 1712.01823

          • ljk November 28, 2017, 9:45

            How badly would an advanced ETI need to know what is going on with Earth and its inhabitants that it needs constant up-to-the-minute news? We have barely put a toe in the cosmic waters let alone interact with any kind of galactic community.

            If they are a long-lived society especially with a truly cosmic perspective, they can monitor us now and then without losing any really important data. They will be into long-term trends affecting things on galactic scales.

      • Curious November 23, 2017, 1:17

        To entertain this thought:

        Maybe the real “signal” is that its trajectory is altered by something other than predictable gravitational forces of the objects it encounters. Perhaps an advanced civilization would capture and send out an asteroid on a planned but eventually returning path to a collection of stars, with the idea that if it came across a suitably capable civilization they would stop/slow it to study it, thus upsetting the planned course and revealing itself (even if not “where” but at least “is”).

        • DJ Kaplan December 22, 2017, 18:01

          Entertaining indeed.
          What about this? The tumbling of the entire “craft” (if such it is) would provide artificial gravity to its crew. By simply flying past, they may be showing us how to solve one of our problems in space exploration.
          By the same token, Columbus sailing by the Caribbean, within sight of the canoe-bound natives, hoping that they will get a clue.

    • ljk November 22, 2017, 13:39

      At least in the first novel, Rama only came to our Sol system to fuel up via our yellow dwarf star before heading on its way to parts unknown. There was no obvious interest in either studying or communicating with any natives of the system.

      If ‘Oumuamua were an ETI probe designed to contact us, I assume it would not be barreling through our system but actually find a way to stop and set up shop somewhere in our celestial neighborhood. Unless it plans to….

      As you said, if this is some kind of scouting or science mission, it would make little sense for the probe to be broadcasting to us any more than a human spy or naturalist would go around shouting to attract the targets of their study. Unless by chance we happen to get caught in its line of sight if the probe happens to be sending a transmission to its home base.

      Just as with Rama, the biggest cosmic insult perceived by humanity would be an alien vessel that did not come here to focus on the talking primates with car keys of Sol 3. We assume ETI would only come to the Sol system to converse with or at least study us, but they may have something totally different in mind. Just as we tend to focus on Earthlike exoplanets when other types of worlds may be of more interest or importance.

    • Charley November 22, 2017, 14:00

      If you want to continue this particular line of reasoning, then and when did be far more reasonable, not only to be silent, but to be undetectable by any electromagnetic radiation signature whatsoever ? Either reflected from radar and radio waves from earth, as well as reflected light from natural sources ? You got to remember that in those science-fiction films like Star Trek where they went back in time that the enterprise was in orbit about a twentieth century Earth where they could have been detected by radar. So what did they do? They put on their cloaking devices, of course ! That way they could fix their ship or whatever and hightail it out of there when the situation got dire for whatever reason.

      And you can’t tell me that advanced alien civilizations would not be smarter than the crew of the enterprise. Come on, I know better than that. So my conclusion is that since the asteroid was not cloaked it has to be a completely natural object.

      • ljk November 22, 2017, 15:42

        Or they didn’t think humans were smart enough to detect them, or even more possibly, they couldn’t have cared less if we knew about their visit or not.

        • DJ Kaplan December 22, 2017, 18:03

          Besides, the cloaking device was invented by the Romulans. :)

          • ljk January 10, 2018, 14:02

            Yes but the Federation stole it in a sneaky operation and a plucky starship engineer was able to get the alien technology to work with the Starfleet systems in a matter of minutes after having access to it for the first time. They even captured a Romulan commander in the process.

  • Charley November 22, 2017, 13:44

    “Besides astronomical observations of this unique object, there is also this remote possibility: , having perhaps dropped down to interplanetary-scale velocities in order to take data during its transit of our solar That this interloper is an interstellar survey probesystem, before going on to another star.

    If this is the case, then perhaps we ought to be looking rather broadly in the electromagnetic spectrum for any signal it might send to us, having easily detected leakage from Earth. That assumes it would try to respond to us using frequencies it knows we use. That would certainly include the microwave bands 1-10 GHz, where most of our radiation leakage radiation is. ”

    “That this interloper is an interstellar survey probe …”

    Is everybody serious ???

    • ljk November 22, 2017, 16:02

      It’s much more fun than saying it’s just a rock, plus it’s good practice in case a real artificial alien interloper comes along.

      • DJ Kaplan November 22, 2017, 18:17

        At this distance, we couldn’t really tell an alien space craft from a rock. Because, you know, science.

        • Ljk November 24, 2017, 14:20

          More specifically due to our relatively primitive level of science and misplaced social priorities.

          Imagine if we had enough foresight to habe a probe ready to launch for just such situations. If the Universe is kind enough to give us another opportunity then we should consider ‘Oumuamua a wake up call.

  • Andrew Palfreyman November 22, 2017, 14:33

    By all means blast it with a prime sequence in unary. It cannot hurt. Most likely.

    • ljk November 22, 2017, 16:03

      Don’t forget lasers and x-rays. Radio waves may be much too primitive for it.

  • Marshall Eubanks November 22, 2017, 16:06

    I am basically against METI, but I think that this case is an exception. If it is an artifact, it knows we are here (if it cares to) and we will draw no more attention to it with METI than without. However, what we might do is trigger a response on the sending frequency, which we can then listen to and (hopefully) detect.

    I think of 1I SETI and METI as simple due diligence. If we are going to throw hypervelocity rocks at it, we should make sure that it is not trying to be friendly and talk to us first. That is (IMO) worthwhile no matter how unlikely 1I being a actual ETI artifact is, as long as that probability is not zero.

  • John Freeman November 22, 2017, 18:11

    Why the assumption that, if it were to be an eti’s probe, it will have decellerated to its current velocity? There are scenarios in which its current velocity would be of the order of magnitude of its maximum velocity – the most obvious being that its originators do not have a finite lifespan, and are in no hurry. It is unlikely to be from vega, but a transit time of 300,000 years from there is mentioned. Would that not be perfectly acceptable to intelligences that could hibernate long term, or were ai’s in a geologically stable location etc etc. ?

  • hiro November 22, 2017, 19:30

    Some random person from a remote tribe uses smoke signal trying to contact the Boeing 787/797 flying above his head. Does anyone on the plane really give a darn about what’s happening below?

    Anyway, real advanced civilizations never show their true toys, probably a hollow rock contained tons of nano-machines inside the core.

  • Martin November 22, 2017, 19:54

    To quote from the (draft form of) the paper: “A roughly spherical object with a hemispheric albedo variation of a factor of 10 could also reproduce the lightcurve but this is unlikely based on our current understanding of the surfaces of most asteroids in our solar system and the absence of any sign of volatiles”. So an Iapetus-like albedo variation or some combination of a more reasonable asymmetry and a significant albedo variation could explain the light curves also. Take your pick as to which is more unlikely. I do love the artists’ conceptions I admit.

  • Robin Datta November 22, 2017, 20:01
  • James Oberg November 22, 2017, 23:41

    If it were an artificially fabricated object, there might be flat external surface areas creating random specular reflections during the rotation that could be so brief they wouldn’t be noticed, but just summed into an integrated ‘brightness’ over the instrument’s observation interval. Is ANYBODY dialing their gear to seek brief bright flashes? It’s a long shot, of course, but….

    • Michael Fidler December 1, 2017, 10:42

      1I/’Oumuamua is tumbling.

      Take a look at the light curve at 1.05, it’s definitely doing something but the question is what? The curve is also changing as time progresses, I just hope someone is doing polarization studies of the light from 1I/’Oumuamua!

      “The discovery of 1I/2017 U1 (‘Oumuamua) has provided the first glimpse of a planetesimal born in another planetary system. This interloper exhibits a variable colour, within a range that is broadly consistent with local small bodies such as the P/D type asteroids, Jupiter Trojans, and dynamically excited Kuiper Belt Objects. 1I/’Oumuamua appears unusually elongated in shape, with an axial ratio exceeding 5:1. Rotation period estimates are inconsistent and varied, with reported values between 6.9 and 8.3 hours. Here we analyse all reliable optical photometry reported to date. No single rotation period can explain the exhibited brightness variations. Rather, 1I/’Oumuamua appears to be in an excited rotational state undergoing Non-Principal Axis (NPA) rotation, or tumbling. A satisfactory solution has apparent lightcurve frequencies of 0.135 and 0.126 hr-1 and implies a longest-to-shortest axis ratio of 5:1, though the available data are insufficient to uniquely constrain the true frequencies and shape. Assuming a body that responds to NPA rotation in a similar manner to Solar System asteroids and comets, the timescale to damp 1I/’Oumuamua’s tumbling is at least a billion years. 1I/’Oumuamua was likely set tumbling within its parent planetary system, and will remain tumbling well after it has left ours”.



      “We observed the newly discovered hyperbolic minor planet 1I/‘Oumuamua (2017 U1) on 2017 October 30 with Lowell Observatory’s 4.3-m Discovery Channel Telescope. From these observations, we derived a partial lightcurve with peak-to-trough amplitude of at least 1.2 mag. This lightcurve segment rules
      out rotation periods less than 3 hr and suggests that the period is at least 5 hr. On the assumption that the variability is due to a changing cross section, the axial ratio is at least 3:1. We saw no evidence for a coma or tail in either individual images or in a stacked image having an equivalent exposure time of 9000 s”.


  • Stephen W November 23, 2017, 0:39

    There is still time for it to turn on its Orion engines if it wants to enter a solar orbit.

    Most of the stars visible in the sky like Vega are large bright with lots of UV and x rays. The place to look for ETI would be all the less noticeable yellow and orange stars. If they are not really close most go unnoticed unless a telescope is pointed at them.

    • Ljk November 24, 2017, 14:22

      Or the places where infrared radiation is being generated but no optical counterparts.

  • Curious November 23, 2017, 1:26

    About this shape. Wouldnt a more round asteroid over millions of years of small impacts with dust sized particles it encountered wear it down to such a slender shape along its acis of motion? especially when passing through solar systems? i.e. Maybe this is the shape we should expect?

    • Harry R Ray December 13, 2017, 10:25

      YES! It’s FORMAL name is Haikonal Abrasion. The only issue I have with this for Oumuamua is, during its closest passage to the Sun, the heat that it absorbed should have weakened its short axis and tidal forces should have SPLIT it into two or more pieces.

      • DJ Kaplan December 22, 2017, 18:10

        Harry, do you have a cite for this “Haikonal Abrasion”? It doesn’t come up in searches.
        If this was true, wouldn’t all planetesimals be shaped like cigars?

  • Astronist November 23, 2017, 7:35

    “this remote possibility: That this interloper is an interstellar survey probe, having perhaps dropped down to interplanetary-scale velocities in order to take data during its transit of our solar system, before going on to another star.” – I continue to find the idea that the enormous energy and time expense of interstellar travel is justified by the fleeting glimpse of the target which is all that one gets from a flyby mission is highly implausible!

    • Ljk November 24, 2017, 14:24

      Unless they have far better and faster data gathering capabilities. Or they only needed to know a few precise things about the Sol System.

    • Daniel Suggs November 26, 2017, 16:43

      Maybe they dropped off a few small probes for each of the terrestrial planets? We may want to check that possibility as well.

      • ljk November 28, 2017, 15:37

        It is a nice idea, but what space agency will ever fund such a mission to find alien probes in our Sol system? Private space efforts to the rescue, again!

  • James Benford November 23, 2017, 17:19

    I’d like to point out that the size of ‘Oumuamua is like that recent interstellar fusion rocket concepts. The Project Icarus resulted in detailed designs for Firefly, which is 850 m long and Ghost, 1100 m. So the scale of this object is of the size we expect of an interstellar rocket with the Project Icarus requirement to decelerate into the star system it is visiting.

    Personally, I think that a better name for this object is The Shard. Because of its large aspect ratio, it looks like something broken off of something else. It’s also much like The Shard building in London, which is about the same size, 910 m tall, and has an aspect ratio of 6.

    Charlie: For it to insure it cannot be seen by us, it would have to do “cloaking” across much of the electromagnetic spectrum. We are observing in the visible, infrared and the microwave. The technology we have recently developed for hiding an object is very narrowband. Of course one can hypothesize tremendous capabilities of advanced civilizations, but that’s ‘indistinguishable from magic’ as Bob Forward said.

    John Freeman: I assumed that its observed low velocity would be in order to have enough time to really inspect our solar system. That’s a problem for our Starshot Project because those sailships will be transiting the Alpha Centauri system in less than an hour. That’s a short time to take data about a number of planets.

  • Anonymous November 24, 2017, 4:13

    Here’s a fun thought: Imagine we send a probe to observe it but it’s no longer where we expected it to be.

  • Harry R Ray November 24, 2017, 10:30

    I don’t Know that it even still exists, but the IDEAL entity to listening for radio/microwave transmissions from Oumuamua 24/7 would be something like the SETI League, instead of the larger radio telescopes who have “much more important work to do.”

    • Ljk November 24, 2017, 14:28

      How many members of The SETI League are still conducting SETI and how often? How about other similar amateur groups?

      I know in the 1990s the hope of The SETI League was to have five thousand amateur radio telescope stations across Earth conducting SETI. Sadly they never reached even a decent fraction of that number.

  • Brian Burgess November 24, 2017, 20:37
    • Shaun November 25, 2017, 6:06

      Now that really is a frightening thought!

  • Michael Simmons November 27, 2017, 2:37

    Regardless of whether this was a natural object or not, I feel we should be more capable of detecting and scanning anything that buzzes the inner solar system from outside in the unlikely event it is an alien probe.
    For any nearby advanced civilization, we would be detectable and once detected, of interest to them.

    • DJ Kaplan December 22, 2017, 18:12

      We can barely detect the asteroids that might impact Earth.

  • ljk November 28, 2017, 11:20

    Oh no! The “super rich” are supporting SETI:


    Considering the track record of the US Government when it comes to SETI and the science community in general, if very wealthy individuals are the ones getting the job done, then so be it. Not exactly the first time in history this has happened.

    A superrich may also get us to Enceladus sooner than any government funded space agency to find out if it has native life forms or not. Anyone here upset about that?


    Interesting that Carl Sagan predicted this in his 1985 novel Contact with S. R. Hadden sponsoring first SETI and then the Machine that took Ellie Arroway et al (in the novel there were multiple travelers to meet the ETI) through space via an artificial cosmic wormhole.


  • ljk November 28, 2017, 11:22

    Party of one: why we’re still alone in the universe

    Astronomers have been scanning the sky for more than half a century to look for signals for alien civilizations, without success. Michael Morgan proposes some reasons why that’s the case in a universe that is likely teeming with life.

    Monday, November 27, 2017


  • ljk December 5, 2017, 16:33

    ‘Oumuamua Mia! Studying the First Interstellar Asteroid

    November 15, 2017

    Bryce Bolin, Senior Researcher at B612’s Asteroid Institute, discusses 1I/’Oumuamua, the first interstellar asteroid discovery, and how the Asteroid Institute team is studying it.


    To quote:

    More than three weeks ago on October 18, 2017, the first interstellar object (ISO) discovery was made. Initially designated as a comet by the Minor Planet Center, C/2017 U1, the ISO now known as 1I/’Oumuamua was soon discovered not to behave in any way like a comet should, which raised questions about its origins. Initially, the object was thought to originate far outside the solar system in a region known as the Oort cloud where it can have extreme orbits that take them careening through the inner solar system at speeds exceeding 60 km/s. What made the apparition of 1I/’Oumuamua different is that its speed was too high to have a solar system origin. As it was passing within perihelion distance, 1I was moving at 87.7 km/s, about 4.2 km/s too fast for it to be bound to the sun.

    The MPC had to give 1I its own special designation because an interstellar object had never been observed before. The last time a non-man made object was seen leaving our solar system was in 1980 with the discovery of comet C/1980 E1 Bowell. C/1980 was not a true interstellar object because it originated inside our solar system and was thrown out of the confines of our Sun’s gravity because of the strong gravitational influence of Jupiter. Given that the existence is so novel, the MPC had to designate it with the number “1” and give it the name meaning “first messenger” in Hawaiian. Maybe 1I is a messenger from another star system, but what can it really tell us about where it came from?

  • ljk December 11, 2017, 10:40

    Alien Probe or Galactic Driftwood? SETI Tunes In to ‘Oumuamua


    To quote:

    Astronomers scrambling to glimpse the fading object have revealed additional oddities. ‘Oumuamua was never seen to sprout a comet-like tail after getting close to the sun, hinting it is not a relatively fresh bit of icy flotsam from the outskirts of a nearby star system. This plus its deep red coloration—which mirrors that of some cosmic-ray-bombarded objects in our solar system—suggested that ‘Oumuamua could be an asteroid from another star. Yet those same observations also indicate ‘Oumuamua might be shaped rather like a needle, up to 800 meters long and only 80 wide, spinning every seven hours and 20 minutes.

    That would mean it is like no asteroid ever seen before, instead resembling the collision-minimizing form favored in many designs for notional interstellar probes. What’s more, it is twirling at a rate that could tear a loosely-bound rubble pile apart.

    Whatever ‘Oumuamua is, it appears to be quite solid—likely composed of rock, or even metal—seemingly tailor-made to weather long journeys between stars. So far there are few if any wholly satisfactory explanations as to how such an extremely elongated solid object could naturally form, let alone endure the forces of a natural high-speed ejection from a star system—a process thought to involve a wrenching encounter with a giant planet.

    These bizarre characteristics have raised eyebrows among professional practitioners of SETI, the search for extraterrestrial intelligence, who use large radio telescopes to listen for interstellar radio transmissions from other cosmic civilizations. If ‘Oumuamua is in fact artificial, the reasoning goes, it might be transmitting or at least leaking radio waves.

    So far limited observations of ‘Oumuamua, using facilities such as the SETI Institute’s Allen Telescope Array, have turned up nothing.

    But this Wednesday at 3 p.m. Eastern time, the Breakthrough Listen project will aim the West Virgina-based 100-meter Green Bank Telescope at ‘Oumuamua for 10 hours of observations in a wide range of radio frequencies, scanning the object across its entire rotation in search of any signals.

    Breakthrough Listen is part of billionaire Yuri Milner’s Breakthrough Initiatives program, a collection of lavishly-funded efforts aiming to uncover evidence of life elsewhere in the universe. Other projects include Breakthrough Starshot, which intends to develop and launch interstellar probes, as well as Breakthrough Watch, which would use large telescopes to study exoplanets for signs of life.

    “With our equipment at Green Bank, we can detect a signal the strength of a mobile phone coming out of this object,” Milner says. “We don’t want to be sensational in any way, and we are very realistic about the chances this is artificial, but because this is a unique situation we think mankind can afford 10 hours of observing time using the best equipment on the planet to check a low-probability hypothesis.”

    Besides being simply a search for signs of aliens, Breakthrough Listen’s efforts could also narrow down the possibilities for ‘Oumuamua’s composition by looking for signs of water vapor sublimating from any sun-warmed ice lurking beneath the object’s red, desiccated surface.

    • ljk December 11, 2017, 10:50

      A further important quote from the above SA article:

      “Typically in astronomy we don’t see things that are rare—if we see one, that means there’s a lot more out there,” says Breakthrough Listen’s lead scientist Andrew Siemion, who is also director of the Berkeley SETI Research Center. “So, while this is most likely a natural object, if we don’t eventually see any more, that would indeed be very strange and would increase interest from a SETI perspective.”

      Either way, Siemion says, “‘Oumuamua’s presence within our solar system affords Breakthrough Listen an opportunity to reach unprecedented sensitivities to possible artificial transmitters and demonstrate our ability to track nearby, fast-moving objects. Whether this object turns out to be artificial or natural, it’s a great target.”

      The same can be said for Tabby’s Star: That we found it in such a narrow sky search by Kepler says we either got very lucky or TS is not uncommon. And if TS type systems are common, why is that if we have not found them before? Simply because our astronomy is still trying to get up to snuff?

  • Harry R Ray December 11, 2017, 11:17

    UPDATE: On Wedensday STARTING at 3 PM EST, Breakthrough Listen will be using the Green Bank Telescope to observe Oumuamua for 10 hours(3 PM to 1 AM). Results from ATA are in and they are negative, BUT; the were NOY listening for ARTIFICIAL signals, but; instead , for NATURAL water signals ONLY!

  • ljk December 11, 2017, 14:14

    Detailed Profile of Our Solar System’s Interstellar Intruder ‘Oumuamua

    Press Release – Source: JHUAPL

    Posted December 10, 2017 9:16 PM


  • stephen December 11, 2017, 15:00

    Could it have had a close encounter with a high-gravity object which stretched it into an elongated shape? Is there a way to test for that?

  • ljk December 12, 2017, 10:27

    How to recognise an alien spaceship

    If an emissary from an alien civilisation visited the solar system, how would we detect it? Lauren Fuge investigates.


    Would we spot an alien probe at all?

    In Horner’s opinion, it is enormously unlikely that we would spot any interstellar object, regardless of origin: “We’re only just reaching the technological level to have a good chance of catching these things.”

    For interstellar objects to be spotted by automated surveys like Pan-STARRS, they need to come close enough to the Sun and Earth and need to be in convenient places in the sky. Horner believes that if `Oumuamua had come along just a fortnight earlier or later, we probably would have missed it, as it would have been too far from Earth or too close to the Sun in the sky.

    “We could be missing most objects of this sort of size,” British space scientist Duncan Steel agrees. “If there are many such objects that are smaller still – as is to be expected – then the vast majority will not be detected by present surveys.”

    Future technology will expand our abilities to spot and study interstellar objects. According to Jewitt, in 2022 Pan-STARRS will “be eclipsed by the much more powerful Large Synoptic Survey Telescope (LSST), which should pick [interstellar objects] up by the bucket-load.”

    Astronomers estimated at least one interstellar asteroid similar to `Oumuamua passes through our Solar System every year.

    According to Hainaut, every one of these objects will be a challenge to study. “No object is ever exactly like any other that we have observed before,” he says. “Each object is an opportunity to learn something more.”

    Detecting and carefully studying these objects will allow us to build up a database of their properties. If an artificial visitor does arrive, we’ll have a better chance of recognising its true nature. And then the real fun will begin.

    • DJ Kaplan December 22, 2017, 18:23

      “The brightness of a spaceship, on the other hand, would be likely to be more stable.”
      If a spacecraft is creating artificial gravity (as we will need to if we want to get off this mudball), wouldn’t that necessarily creating non-stabile brightness?

  • ljk December 12, 2017, 11:23

    Breakthrough Listen is Going to Scan ‘Oumuamua, You Know, Just to be Sure it’s Just an Asteroid and Not a Spaceship


    To quote:

    Listen’s observation campaign will begin on Wednesday, December 13th, at 3:00 pm EST (12:00 PST), This 100-meter telescope is the world’s premiere single-dish radio telescope and is capable of operating at millimeter and submillimeter wavelengths. It is also the mainstay of the NSF-funded Green Bank Observatory, located in West Virginia.

    The first phase of observations will last a total of 10 hours, ranging from the 1 to 12 GHz bands, and will broken down into four “epochs” (based on the object’s rotational period). At present, ‘Oumuamua is about 2 astronomical units (AUs) – or 299,200,000 km; 185,900,000 mi – away from Earth, putting it at twice the distance between the Earth and the Sun. This places it well beyond the orbit of Mars, and over halfway between Mars and Jupiter.

    At this distance, the Green Bank Telescope will take less than a minute to detect an omni-directional transmitter with the power of a cellphone. In other words, if there is a alien signal coming from this object, Breakthrough Listen is sure to sniff it out in no time! As Andrew Siemion, Director of Berkeley SETI Research Center and a member of Breakthrough Listen, explained in a BI press statement:

    “‘Oumuamua’s presence within our solar system affords Breakthrough Listen an opportunity to reach unprecedented sensitivities to possible artificial transmitters and demonstrate our ability to track nearby, fast-moving objects. Whether this object turns out to be artificial or natural, it’s a great target for Listen.”

    Even if there are no signals to be heard, and no other evidence of extra-terrestrial intelligence is detected, the observations themselves are a opportunity for scientists and the field of radio astronomy in general. The project will observe ‘Oumuamua in portions of the radio spectrum that it has not yet been observed at, and is expected to yield information about the possibility of water ice or the presence of a “coma” (i.e. gaseous envelop) around the object.

    During the previous survey, data gathered using the VLT’s FOcal Reducer and low dispersion Spectrograph (FORS) indicated that ‘Oumuamua was likely a dense and rocky asteroid with a high metal content and little in the way of water ice. Updated information provided by the Greenbank Telescope could therefore confirm or cast doubt on this, thus reopening the possibility that it is actually a comet.

    Regardless of what it finds, this survey is likely to be a feather in the cap of Breakthrough Listen, which already demonstrated it’s worth in terms of non-SETI astronomy this past summer. At that time, and using the Green Bank Radio Telescope, the Listen science team at UC Berkeley observed 15 Fast Radio Bursts (FRBs) for the fist time coming from a dwarf galaxy three billion light-years from Earth.

  • ljk December 13, 2017, 11:07

    Today is the day…


    Doesn’t hurt to have the chair of the Harvard Astronomy Department involved, either. Especially when he says things like this:

    Loeb is an alumnus of Hebrew University in Jerusalem, a school that was founded by one of his heroes, Albert Einstein. Like the Nobel Prize-winning physicist, Loeb shares a sense of unbridled excitement about the possibilities of our universe. “Perhaps the aliens have a mother ship that travels fast and releases baby spacecrafts that freely fall into planetary system on a reconnaissance mission,” he told us. “In such a case we might be able to intercept a communication signal between the different spacecrafts.”

    The potential evidence of intelligent life beyond Earth is racking up at a steady clip since the various Breakthrough initiatives have begun employing the Green Bank Telescope. In August, scientists detected 15 brief but powerful radio pulses emanating from a mysterious and repeating source far across the universe.

    Loeb sees this week’s listening session as perhaps the beginning of something bigger. “If this object is natural in origin, there should be many more like it in the solar system,” he explained. “Therefore we should find many more … and even if most of them are natural, perhaps one of them will be found to be of artificial origin, some space device or junk from an alien civilization, the exceptional ‘needle in the haystack’ that we all hope to find one day.”

  • ljk December 13, 2017, 16:50

    Speculation by Jason Wright if the object is an alien vessel with a broken propulsion system but still functioning:



    Will anyone be transmitting TO ‘Oumuamua, if I may dare to ask such a question?

  • ljk December 14, 2017, 16:42

    14 December 2017




    ** Synopsis: No evidence of artificial signals emanating from the object so far detected by the Green Bank Telescope, but monitoring and analysis continue. Initial data are available for public inspection in the Breakthrough Listen archive. **

  • ljk December 18, 2017, 15:08

    So according to this headline from this British “newspaper”, Stephen Hawking probed in *inside* of the “mysterious spaceship” that is vaulting through our Sol system:


    And we wonder why the general public is as misinformed and confused as they are when it comes to space science and aliens.

  • ljk December 20, 2017, 10:54

    ‘Oumuamua Update: Red, Tumbling, and Silent

    By: Kelly Beatty | December 19, 2017

    Astronomers’ recent observations of our first-known interstellar visitor reveal that it is very strange indeed.


    It is so cute to watch professional astronomers try to distance themselves from the idea of doing SETI on ‘Oumuamua while secretly following the project and hoping for a signal.

    Maybe some day we will grow up enough as a species to not treat the idea of alien life with a combination of bemusement, dread, and rejection, but then again I will probably see the media use an actually different artwork representing ‘Oumuamua before that happens!

  • ljk January 10, 2018, 14:11

    The Atlantic’s take on the SETI effort for ‘Oumuamua, including a link to the very recently released results paper:


    To quote:

    Enriquez said Breakthrough Listen currently has no plans for follow-up observations, but the team will continue to examine the results of the observations. Now that they’ve looked for continuous radio signals in the data, they’ll look next for pulsating signals.

    When I asked whether they’re ready to call it—move along, nothing SETI to see here—Enriquez said such certainty isn’t quite possible, thanks to the nature of SETI experiments in general. Astronomers are limited not by the extent of their search, but by the capacity of current technology. The GBT and other radio telescopes are not able to study ‘Oumuamua in every frequency.

    “We were not able to observe at other frequencies, so we don’t know if, for instance, that it might have been a signal that is lower than the frequency that we observed or higher than the frequency that we observed,” Enriquez said. “And unfortunately, that’s kind of the end of the experiment.”

  • ljk April 10, 2018, 9:28

    Outback radio telescope listens in on interstellar visitor

    April 10, 2018

    A telescope in outback Western Australia has been used to listen to a mysterious cigar-shaped object that entered our Solar System late last year.

    The unusual object—known as ‘Oumuamua—came from another solar system, prompting speculation it could be an alien spacecraft.

    “So astronomers went back through observations from the Murchison Widefield Array (MWA) telescope to check for radio transmissions coming from the object between the frequencies of 72 and 102MHz —similar to the frequency range in which FM radio is broadcast.

    While they did not find any signs of intelligent life, the research helped expand the search for extra-terrestrial intelligence (SETI) from distant stars to objects closer to home.

    Full article here:


    To quote:

    Professor Tingay said the research team was able to look back through all of the MWA’s observations from November, December and early January, when ‘Oumuamua was between 95 million and 590 million kilometres from Earth.

    “We found nothing, but as the first object of its class to be discovered, `Oumuamua has given us an interesting opportunity to expand the search for extra-terrestrial intelligence from traditional targets such as stars and galaxies to objects that are much closer to Earth.

    “This also allows for searches for transmitters that are many orders of magnitude less powerful than those that would be detectable from a planet orbiting even the most nearby stars.”

    ‘Oumuamua was first discovered by the Pan-STARRS project at the University of Hawaii in October.

    Its name loosely means “a messenger that reaches out from the distant past” in Hawaiian, and is the first known interstellar object to pass through our Solar System.

    Paper online here:

    “A Serendipitous MWA Search for Narrow-band and Broad-band Low Frequency Radio Transmissions from 1I/2017 U1 `Oumuamua’, published in The Astrophysical Journal on April XXth, 2018.