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An Interstellar Visitor?

An object called A/2017 U1, whether it is an asteroid or a comet, is drawing attention because it seems to be an interstellar wanderer. Discovered on October 19 by the University of Hawaii’s Pan-STARRS 1 telescope on Haleakala, the object was quickly submitted to the Minor Planet Center by Rob Weryk (University of Hawaii Institute for Astronomy, IFA). Weryk was subsequently able to identify the object in Pan-STARRS imagery from the previous night.

Image: This animation shows the path of A/2017 U1, which is an asteroid — or perhaps a comet — as it passed through our inner solar system in September and October 2017. From analysis of its motion, scientists calculate that it probably originated from outside our Solar System. Credit: NASA/JPL-Caltech.

Thus a nightly search for near-Earth objects may have uncovered an object whose origins lie much further away. A/2017 U1 is about 400 meters in diameter and on a highly unusual trajectory, one that fits neither an asteroid or comet from our own Solar System. Davide Farnocchia (JPL) is a scientist at NASA’s Center for Near-Earth Object Studies (CNEOS):

“This is the most extreme orbit I have ever seen,” said Farnocchia. “It is going extremely fast and on such a trajectory that we can say with confidence that this object is on its way out of the Solar System and not coming back.”

Thus we seem to be looking at an object unattached to any star. That such objects exist is hardly a surprise, as we already know there is a robust population of planets that have been ejected from their own stellar systems and wander alone through interstellar space. But if confirmed as such a wandering object, A/2017 U1 would be the first ever observed coming through our own Solar System.

“We have long suspected that these objects should exist, because during the process of planet formation a lot of material should be ejected from planetary systems. What’s most surprising is that we’ve never seen interstellar objects pass through before,” said Karen Meech, an astronomer at the IfA specializing in small bodies and their connection to Solar System formation.

Coming from the direction of the constellation Lyra and moving at 25.5 kilometers per second, A/2017 U1 evidently entered our Solar System from above the ecliptic, crossing the ecliptic plane inside the orbit of Mercury and reaching perihelion on September 9. As the illustration above makes clear, its trajectory was deflected by the Sun’s gravity and it passed ‘under’ the Earth’s orbit on October 14 at a distance of some 24 million kilometers. It is now back above the plane of the planets, moving at 44 kilometers per second, heading toward Pegasus.

Image: The Pan-STARRS1 Observatory on Halealakala, Maui, opens at sunset to begin a night of mapping the sky. Credit: Photo by Rob Ratkowski.

We’ll have to see what naming conventions come into play if this object is indeed confirmed as an interstellar traveler, putting the onus on the International Astronomical Union to come up with something interesting. You may remember that asteroid 31/439 wound up getting named ‘Rama’ in Arthur C. Clarke’s fine tale Rendezvous with Rama (1973), though we’re unlikely to find that A/2017 U1 is as intriguing as Clarke’s mysterious starship bound for the Magellanics.

Meanwhile, we’re reminded of yet another reason why wide-field surveys of the sky make sense. While we engage in the great task of planetary protection, we also make discoveries like this one, following up with the kind of detailed observations now underway. Compiling the necessary data will help us pin down the origin of this intriguing visitor.


Comments on this entry are closed.

  • ljk October 27, 2017, 9:03

    This is a link to the official press release:


    And meanwhile we wait for the Rendezvous with Rama…


    • Jim Noord November 22, 2017, 11:09

      Am I stating the obvious or wasn’t this exactly like what we do with under-powered unmanned probes getting a gravitational slingshot/course correction from our star via close flyby to the sun and checking for signs of intelligent life in the “Goldilocks zone” (or mining potential) and then onto the next star? If quantum communications were inboard, a largely inert object could potentially be used to camouflage an protect relatively fragile sensing and communication components. This could be a forward probe preceding a larger presence if suitable condition were discovered here. Bottom line, we need to get ourselves into space and not with Saturn 5 with bolt on boosters adn a cement capsule crew module.

      If our government spent what a typical election cycle collectively cost both parties, we’d have been in space decades ago.

  • Alex Tolley October 27, 2017, 9:55

    We’ll have to see what naming conventions come into play if this object is indeed confirmed as an interstellar traveler


  • Michael Fidler October 27, 2017, 10:23

    First they say it’s a comet then they say it’s an asteroid, that does not make much sense??? This object is coming in from deep space and should be emitting large amounts of light gases. It should of been visible long before reaching the inner solar system. Take a look at the comets the have extremely long orbits:

    • Michael Fidler October 27, 2017, 21:54

      10 to 1 if they can not find it, then it’s slowing down and we may be seeing some interesting developments. We should also be keeping a look out for any other object coming in with similar speeds and directions. Where is Flash Gordon when we need him?

    • Jim Noord November 22, 2017, 11:26

      Not if it’s artificial? And how many cylindrical presumably metallic asteroids? that would be a tough one to form from natural processes. Good question would be what is the mass and what do the stenographic analysis show? If extra solar, remote isotopic analysis interferometer should indicate any difference in isotropic concentrations of all elements present than our solar system. That is the first test. (that is how they discovered ice on the moon for instance). In the 1980’s STAR WARS program used this tech for black body detection of ICBMs. specifically in distinguishing real from dummy warheads. Used the moon as a calibration tool (at least that is the rumor). In the process detected He3 as well as lots of Water.

      Something isn’t adding up here. Shape is the real problem, Cylindrical objects would have trouble forming in nature like that. what it is made of tells a tale. That is the starting point and ending point here, not conjecture. The thing definitely got a gravitational assist and eject from our solar system. Question is where’d it come from? Again isotropic analysis should narrow that down. Stellar isotropic signatures would indicate where and what direction this came from if it is from relatively recent origin. Time to start looking or chase the thing with our non existent military space program vehicles and ask it! HAH

  • Harry R Ray October 27, 2017, 10:34

    Paul Gilster: In response to your quote “…we’re unlikely to find that A/2017 U1 is as intreguing as Clarke’s mysterious starship bound for the Megellanics.” You are probably right, but a couple of co-incedences pop up that might suggest otherwise. ONE: Perihelions closer than Mercury for comets originating in the Oort cloud are common because trajectories are radial in nature with the Sun as one of the focal points. However, this is NOT the case for an interstellar object which would have NO REFERENCE POINTS WHATSOEVER The Sun would NOT be able to pull in an object traveling at 25.5 KPS either. I estimate that only one in ten thousand such objects would have a perihelion that close, and the great majority would actually have near STRAIGHT-LINE trajectories passing through the plain of the solar system. THEN: Add the “near misses”(i.e.)the ones that do not even CROSS the plain of the solar system, and the odds go up to one in a MILLION!!! Therefore, the odds should have been OVERWHELMING that the first extra-solar asteroid detected would NOT have this kind of trajectory. However, there are TWO ways out of this conundrum. One is that this object is simply an Oort cloud asteroid. Astronomers predicted eight billion(out of the hundreds of trillions of TOTAL objects in the Oort cloud)such objects exist, but this way out can only be based on further observations resulting in a CORRECTED orbit. The other is it is simply a result of objects like this NOT BEING DETECTED AT ALL unless they DO pass close to the Sun. The problem I see with this way out, is that MILLIONS of extra-solar objects of `400 METERS IN SIZE should have had close encounters with our solar system since the inception of PANSTARRS, and some should have been found by astronomers looking through the PANSTARRS archives for Planet 9. My question to you is, could you check with Mike Brown, or someone on his team to see if my assumptions are correct? RSVP ASAP! Thanks. P.S. Two other “co-incedences” also pop up. ONE: The OUTWARD trajectory of this object is IDEAL for a “far encounter” type of ALL FOUR of the inner planets of the solar system. The odds are only 1 in 360 that such a trajectory would occur naturally. TWO: If this asteroid originated around Boyajian’s Star, and had been hollowed out and fitted with a thruster powerful enough to fly it out of the star’s gravitational influence, and head it toward our sun hundreds of thousands of years ago while Boyajian’s Star was in the constellation Lyra, instead of nearby Cygnus, that would be the SMOKING GUN! The odds of this object originating from this area of the sky are only about 100 to one, just where the most promising SETI target is. If you could find out what Boyajian’s Star’s proper motion is to see if it WAS in Lyra hundreds of thousands of years ago, I would appreciate that, too.

    • Michael Fidler October 27, 2017, 21:47

      Well all I can say, that’s pretty far out. ; -}

    • hiro October 28, 2017, 23:02

      Probably coming from either Wolf 359 or Lalande 21185 if this object is indeed coming from outside this star system. The only problem is moving too close to Sol, interstellar objects’ trajectories usually don’t come anywhere near the main star of the system, this is exceptionally rare, maybe too rare…..

    • hiro October 29, 2017, 0:33

      My bad, it’s more like Struve 2398.

      • Harry R Ray October 29, 2017, 13:34

        Rumor has it that the object is EXTREMELY RED. Tholins or red paint?

        • hiro November 1, 2017, 16:37

          “Angry Asteroid”.

          • Harry R Ray November 3, 2017, 9:50

            Actually, its BLUSHING!!! Caught in the act with NO CLOTHES ON! It’s SOOOOOOOOO shy!!! lol.

    • Harry R Ray November 1, 2017, 9:43

      A couple of VERY IMPORTANT CORRECTIONS! ONE: The ORIGINAL 400 meter diameter was based on a comet-like albedo of ~.02. A more REALISTIC(though yet UNPROVEN)asteroid-like albedo of ~.10 would put the diameter of ~150 meters. But, since we are dealing with overall LUMINOSITY as the driving function of detectibility, this does not have a GREAT impact on the number of objects like this EXPECTED to be detected. What does,though, is; for some reason I cannot comprehend, the GREAT MAJORITY of ubjects like this will approach PERPENDICULAR to the plane of the planets in our solar system, making one in ten thousand the true odds of such an object getting so close to the Sun. Greg Laughlin predicts that such close passages to stars for such objects occur only several QUADRILLION years per object. I would like him to compute the likelihood of such an object passing 15 million miles to a planet in another star system hosting intelligent life, invoking the Drake Equation. My guess, is that if this is due to ONLY NATURAL CAUSES, there may be only ONE SUCH NATURALLY CAUSED EVENT in the lifetime of the ENTIRE UNIVERSE!!! Finally, it would take a WHOPPING 16 MILLION years for an object travelling at that speed to reach us from Boyajian’s Star, as opposed to the MERE hundreds of thousands, which I ORIGINALLY proposed.

      • Harry R Ray November 10, 2017, 10:39

        The RATE of passages of interstellar comets/asteroids through the PLANE of our solar system has now been FIXED[“Implications for planetary system formation from interstellar object 1I/2017 U1(Oumuamua).” by David E. Trilling, Tyler Robinson, Alissa Roegge, Colin Orion Chandler, Nathan Smith, Mark Loeffler, Chad Trujillo, Samuel Navarro-Meza, Lori M. Glaspie.]at one every ~5 years. Therefore, if a SERIES of these objects were to appear over a VERY SHORT PERIOD of several weeks to a couple of months, the chances are that ALL objects IN THAT SERIES would NOT be of NATURAL origin!

      • Harry R Ray November 12, 2017, 15:00

        UPDATE: 1I/2017 Uomuamua appears to be three times as LONG as it is WIDE and rotating every 3 t0 5 hours with the halfway distance of the LENGTH AND WIDTH as its center of gravity. SPECULATION ALERT: If this object did just happen to be hollowed out, what would be the artificial gravity RANGE at the two TIPS? Anyone?

        • Harry R Ray November 13, 2017, 10:41

          1.3 million years ago, 1I/Oumuamua came within 0.16 parsecs of the nearby star, TYC4742-1027-1. “The origin of interstellar asteroidal objects like 1I/2017 U1.” by Simon Portegies Zwart, Inti Pelupessy, Jeroen Bedorf, Maxwell Cai, Santiago Torres.

        • Harry R Ray November 16, 2017, 10:53

          ANOTHER paper claims that the axis ratio MAY be ~6 to 1(~230 meters by ~35 meters)INSTEAD of ~3 to 1! If this is the case, Oumuamua is STARTING to look like an extremely scaled DOWN version of Rama!!! “Interstellar Interloper 1I/2017 U1: Observations from the NOT and WIYN Telescopes.” by David Jewitt, Jane Luu, Jayadefv Rajigopal, Ralfko Tulla, Susan Ridgeway, Wilson Liu, Thomas Augusteijn.

  • Al Jackson October 27, 2017, 11:02

    I did comet work at one time in the past. I remember , among the comet researchers , how puzzling it was that after 2 centuries of good comet observation and computed orbits that not a single one with ‘excess’ energy has been seen coming into the solar system. All those , in the catalog, with hyperbolic orbits relative to the sun had been thrown out by Jupiter. This is a first.

    • ljk October 27, 2017, 16:50

      As I recall, until we started monitoring the Sun with satellites like SOHO, we actually missed a lot of comets that barreled into our star, and all of which so far as we know came from our Sol system.

      So if we missed those comets, many of which even produced tails, would it not have been even more difficult to find extrasolar comets barreling into our system and out? Note that it took an automated observing system just to find this one, and even it did not detect its special properties right away.

      There is undoubtedly a lot that likely goes on in our Sol system which we do not see because only a fraction of our effort and funding goes to such observing – and most of it remains on Earth. Had this comet appeared just a few decades ago we probably would have missed it, and no doubt we likely have missed many extrasolar objects.

    • Harry R Ray October 30, 2017, 9:46

      Please read:” On the non-detection of extra-solar comets”, which is now up on the exoplanet.eu website.

  • LuigiG October 27, 2017, 15:49

    Random thought: assuming the object is indeed of extrasolar origin and fantasizing about being given (much, much) more notice… would it not make sense to have an interplanetary probe ready to ‘launch and latch’ onto objects like this one, especially considering how (relatively) close to Earth its trajectory is?
    I mean, given the fact that aren’t any actual interstellar probes launching anytime soon, having bits of other planetary systems delivered to your doorsteps seems must-seize opportunity for exploration and study, no?

    • DJ Kaplan October 27, 2017, 16:27

      Luigi, if you are implying that the object can be an ersatz space vehicle, I’m pretty sure that it’s not going faster than anything else we can manufacture and launch.

      That said, of course examining the object’s makeup up close would be another first: landing on an “extraterrestrial” body.

      • LuigiG October 28, 2017, 3:43

        Hi DJ, no, definitely the latter. A vehicle seems exceedingly unlikely to me, although I guess that hypothesis would be hard to disprove with the data we have.
        But say the body comes from another star’s ‘exoKuiper belt’, being able to look at its morphology, composition, isotope ratios etc. should be highly interesting …to me, even a ‘simple’ photo of good resolution would be amazing!

    • Brett Bellmore October 28, 2017, 11:36

      It doesn’t really gain you anything, because you need just as much delta-V to match speeds with it, as if it weren’t there to begin with. It isn’t as though you can just harpoon it with a stretchy line as it goes by. (Even carbon nanotubes aren’t that stretchy!)

      What it would be very useful for, is slow interstellar colonization. You’d match speeds with it and have all that handy mass that you hadn’t had to accelerate.

  • hiro October 27, 2017, 15:57

    Lol, this is a good plot for future SF novel Pushing Ice 2.0: this piece of ice was meant to hit the Earth but those ancient ET mathematicians smoked weed when they did the calculations hence they didn’t correct the long term perturbation of the planet’s orbit.

    Anyway, how did this object come to this star system? The only way is a fictional planet X (mini gas giant) above the plane affected the trajectory of this object, hmm….

  • Ioannis Kokkinidis October 27, 2017, 17:21

    I am pretty sure that the IAU will give it a catalog name with a designation like IO-2017-1 or something boring like that, where IO meaning Interstellar Object. Space probe on standby is a great idea, proposed in conjunction with Spaceguard, the protection from rogue asteroids. Consider though that it takes something like 4 years minimum to build a space probe and that as far as I remember the USAF had a Delta II in 30 or 60 day readiness during the Cold War. Assuming we had a probe, which would need to be modernized on a regular basis raising the cost, see DMSP-19 where storing it for year and modernizing it proved more expensive than originally building it, 30 days may not be enough. We are lucky we even found the object, but we will not be able to do better than ground observations for a long time

    • Harry R Ray October 29, 2017, 13:25

      If it does turn out to be an asteroid, they will HAVE to give it a REAL NAME instead of JUST a designation, and all bets are on Rama! The only thing that puzzles me is why “Rama”(a MAJOR Hindu deity)has not been used ERLIER.

  • Martin October 27, 2017, 19:08

    I don’t think I believe it. Assuming random orientations of the sun and objects trajectories my back-of-theExcel-spreadsheet calculations suggest you would need on the order of ten to the sixteenth such objects (per star) in order for us to detect one passing by in the time we’ve been (sort of) looking. Of course I was just using the equation for collisions in a gas, which ignores irritating thing like gravity. Hey astrophysicists what would this imply about the number density of such objects (assuming we weren’t really really really lucky).

  • J. Jason Wentworth October 28, 2017, 5:12

    Now would be the perfect time to receive data from all active solar-orbiting (and planet-orbiting) spacecraft in the vicinity of A/2017 U1’s trajectory, to observe it directly (using any spacecraft instruments that have that capability) *and* to observe its interactions with the solar wind and the solar magnetic field, plus any gases or ions that it is emitting due to its irradiation by the Sun’s heat and light. Also:

    Any old solar-orbiting spacecraft that may be near its path, and which could be commanded on (Giotto and Pioneers 6, 7, and 8 are believed to be “awaken-able,” and ISEE-3/ICE definitely is, too [it was communicated with and commanded by the Ames “McMoon’s” team ISEE-3 Reboot Project recently]), could collect fields & particles data on A/2017 U1 as it passes them in their solar orbits.

  • Adam Crowl October 28, 2017, 5:20

    Hi Paul,
    Fascinating sighting. I have to admit as soon as I heard to zanged past Earth at about ~0.16 AU, I thought it was scoping us out, hiding its true nature as an ‘inert’ object. If another object comes winging in from more or less the same direction then the suspicion will be confirmed. The spectrum is (boringly) consistent with space-exposed matter, probably a tholin-like smear on the surface.

    • Alex Tolley October 28, 2017, 15:52

      If another object comes winging in from more or less the same direction then the suspicion will be confirmed

      [Raman] objects 1 & 2 may have already passed by undetected.

    • hiro October 28, 2017, 16:58

      “Hitting below the belt” is very hard to avoid. This is all about the probability of an interstellar object moving straight into our system and coming very close to the sun vs probability of a larger body inside the system (~50-5000 AU above the orbital plane) changing the trajectory of an interstellar object. Almost everything else is more or less crackpot.

      • Harry R Ray October 29, 2017, 13:39

        According to Jason Wright, the MAXIMUM velocity that can be reached is 20 Km/s. Since A/2017 u1 is traveling at 25.5 Km/s. it isn’t even CLOSE! Oh by the way, isn’t it IRONIC that U1 is pronounced “YOU WON”!

        • Michael October 30, 2017, 14:30

          I am wondering if it is a rock thrown at a high inclination by Jupiter and it is now returning although the velocity is higher than normal.

    • Harry R Ray October 29, 2017, 13:30

      You need THREE(oh, by the way, the Ramans do EVERYTHING in threes)and the time period BETWEEN 1(A/2017 u1)and 2 MUST be EXACTLY THE SAME(i.e. within SECONDS)as the time period between 2 and 3. Only THAT would satisfy the Sagan Rule(extrordinary claims require extrordinary PROOF)!

  • Adam Crowl October 28, 2017, 5:56

    Hi again,
    There is this very interesting estimate on the rate at which PANSTARRS would detect ~1 km cometary ISOs (InterStellar Objects), which assumes comet-like activity and detectability, but also mentions inactive asteroid-like objects, which would have smaller detection ranges.
    An Observational Upper Limit on the Interstellar Number Density of Asteroids and Comets
    …the working assumption was the current number detected was zero. Now that can be increased by 1. Seems PANSTARRS might spot many more, if this first catch is ‘typical’.

    • Jeff Wright October 31, 2017, 13:56

      Just a question…

      That’s quite a turn that thing makes after the flyby of our Sun–more along the plane of most of our Solar System.

      What will this pass near?

      Please say “Ceres.”

      Maybe Dawn could–oh, I don’t know–get in its way?

  • Andrei October 28, 2017, 9:46

    @Michael Fidler: They thought comet first, C/2017 U1 but large telescopes show no coma so preliminary was changed to A/2017 U1.
    (C for comet, A for Asteroid)
    It might still be icy object, only not had time to melt and release gas. And more likely came from comet region, Kupier or Oort.
    Passage of sun was like a comet also, so is ok call it ‘comet like’. =)

    @Ioannis Kokkinidis:
    For a probe to fly by, you rather need something simple and sturdy.
    Voiyager tech got old as they did fly, but still did good work.
    So no need to be from latest year model. =)

    Lets choose proven ~10 year old New Horizons. It can work automatic it already is to some tasks so keep computer and programs.
    Add a battery and solar panels, simplify to standard components – design lighter parts again.

    Build 20 together with fairing and coupler for Falcon, New Glenn, Delta IV, Vulcan, Long March, Angara and Ariadne.
    NASA and ESA will take months to launch anything, but SpaceX and Blue origin might launch in days if that fairing and coupler is stored on site. Largest rockets needed to catch A/2017 U1
    Sign a contract with the commercial launchers that any ready fly rocket can be repurposed for launch of special probe – and ordinary cargo wait for next launch.

    Larger rockets in Angara series, Vulcan, Delta and New Glenn could reach A/2017 U1 for fast flyby, over in minutes and small science return.
    If sent on similar path formation flying might be possible and give more data. But it will only reach A/2017 U1 in distant part of solar system, weak light and solar panel will not work well so ‘New horizon special’ go into sleep mode and only activate at rendezvous – therefore battery needed.

    • J. Jason Wentworth October 29, 2017, 9:11

      Andrei, I too have been advocating your idea for some time, of having “target(s) of opportunity probes” waiting in storage for such occasions, and we even have a well-proven model for such probes:

      The simple and inexpensive–yet scientifically fruitful and extremely long-lived (three of them are believed to still be “awaken-able,” even after half a century in space, see: http://en.wikipedia.org/wiki/Pioneer_6,_7,_8,_and_9 )–Pioneer 6, 7, 8, and 9 solar probes embodied the design philosophy of Charles F. Hall, the Pioneer program manager at NASA’s Ames Research Center. His design formula called for using spin stabilization, discrete standard electronic components (*no* microchips [integrated circuits]) which were well “burned in” during flight qualification testing, no onboard computer (just a simple command register capable of storing a few commands for later execution in sequence), and a small, focused selection of instruments (just 8 or so), and:

      Along with the instruments, a simple “push broom imager” (a no-moving-parts, “image line-retina” camera which can take sharp, un-blurred pictures from a spinning spacecraft [the JunoCam aboard the spin-stabilized Juno Jupiter orbiter is a push broom imager], using its rotation to provide the scanning) could also be carried. Such imagers can (and have, aboard several spacecraft) take pictures in visible light and in other wavelengths of light, by using the appropriate filters. A movable planar (flat) mirror, placed “above” the imager’s lens (similar to the arrangement used on the Giotto Halley’s Comet probe), would enable a spin-stabilized “target of opportunity” probe to continually image its target without having to frequently re-orient its spin axis, even during a close, fast-pass flyby. Also:

      Each of the Pioneer 6 – 9 spacecraft has a collinear, medium-gain vertical antenna (which has no moving parts, such as a reflector); it produces a rather thick, “pancake-shaped” beam (antenna pattern), which always covers the Earth. In the case of a “target of opportunity” probe that might be launched above (north of) or below (south of) the ecliptic to reach its target body, the probe’s spin axis could be re-oriented (made to precess temporarily in the pitch and/or yaw directions, that is) using just a single, boom-mounted cold gas (nitrogen) thruster (just as Pioneers 6 – 9 did). This would ensure that the antenna’s beam would cover the Earth, while also putting–and keeping–the target body in the “scan swath” of the probe’s instruments and imager. It might also be possible to use a magnetic torque coil (“worked against” the Sun’s magnetic field) at the tip of a boom, instead of a cold gas thruster. As well:

      Such probes need not be cylindrical as Pioneers 6 – 9 were. Indeed, since their required spin axis orientations couldn’t be predicted (because their target objects might be located at any point on the Celestial Sphere, as viewed from Earth [or even from the Sun]), a probe shape approximating that of a sphere–with solar cells affixed more-or-less equally all over its exterior, to ensure an “even” electrical power output regardless of the spacecraft’s orientation with respect to the Sun–would be preferable. A probe having a regular polyhedral shape (a tetrahedron, cube, octahedron, dodecahedron, icosahedron, or a “mixed-facet polyhedron” [such as the ‘squares-and-triangles’ one used for the early LES–Lincoln Experimental Satellite–spacecraft, see: http://www.thesun.co.uk/news/2244633/abandoned-us-satellite-starts-transmitting-after-50-years/ ]) has a more-or-less constant electrical power level no matter which way it’s oriented, or whether or not it’s spinning, as the many solar cell-powered artificial satellites that have/had these shapes have demonstrated for well over half a century.

  • Jean Schneider October 28, 2017, 13:42

    J. Jason Wentworth wrote “Now would be the perfect time to receive data from all active solar-orbiting (and planet-orbiting) spacecraft in the vicinity of A/2017 U1’s trajectory…”
    Unfortunately A/2017 U1 trajectory makes an angle 60° with the ecliptic
    where all interplanetary spacecrafts are located. So, no chance…
    (with the exception perhaps of Voyager 1 if I am correct).
    BUT, since we are on Centauri Dreams, perhaps in some decades
    a Breakthrough Starshot precursor will be sent to the object at a speed sufficient to approach it.

    • J. Jason Wentworth October 29, 2017, 7:18

      I’m aware of the highly-inclined angle at which A/2017 U1’s trajectory intersects the ecliptic. But at or near the points where its path has–or will–pass through the ecliptic, it’s possible that active (or “hibernating”) solar-orbiting spacecraft may be in positions where relatively close-up observations of the interstellar interloper are possible. (As Pioneer 7, Pioneer 12 [the Pioneer Venus Orbiter], and ISEE-3/ICE showed when they collected useful plasma & UV imagery and fields & particles data on Halley’s Comet during its 1986 apparition, “relatively close-up” can be millions of miles away.)

  • DCM October 29, 2017, 16:00

    Next one, we should simply land instruments and energy sources, program it to awaken at 50 year intervals and send back location and other data. Cheaper than the interstellar ships we’ve sent out.

    • J. Jason Wentworth October 30, 2017, 4:26

      Using such an object as heat and radiation shielding has been proposed for ultra-close solar flybys (by setting up instruments and even small, crew-occupied laboratories below the surfaces of “Sun-grazing” asteroids), going back several decades. Such an arrangement–using a probe that could cover itself with regolith–could also enable an “interstellar rock-riding” probe to protect itself from erosion and galactic cosmic rays.

  • Frank Smith October 30, 2017, 6:35

    Isn’t this a good evidence for possible interstellar panspermia ? I though one of the arguments against pansermia was the odds of transfer of life from other stars was too low because of low probability material from other stars would make it to our solar system.

    If this one made it, then it’s likely others did.

  • kzb October 30, 2017, 8:30

    Adam Crowl, that is an interesting paper. As well as having one observation instead of zero, we also have the fact that it is an asteroid, not a comet. That alone seems to increase the estimated volume density of such objects significantly according to the paper.

  • Mauldred October 30, 2017, 8:36

    The Arachnids have sent another meteor, but this time we’re ready!

  • Harry R Ray October 30, 2017, 9:50

    PLEASE: EVERYONE go to the http://www.oklo.org website and read the LATEST POSTING!!!

  • CharlyUY October 31, 2017, 8:55

    In fact, astronomers cannot affirm is a comet because no cometary activity was detected, so they decided it should be an asteroid, why only these two possibilities? haven’t we already sent in our short technologically advanced history several space probes into deep space? think about Voyager 1&2 reaching a distant solar system and captured by the host star in an hyperbolic orbit in 1 million years or so i.e., with so many exoplanets discovered, is not so crazy to consider an ancient advanced civilization could have also sent space probes million years ago into deep space, the fact the object have the perihelion so close to our sun for a such fast and distant object, could leave the possibility it could have even been intended, I believe this object should have been studied with all the biggest instruments available even ALMA and Arecibo in order to try to determine some kind of electromagnetic activity and its composition. Just a though, just another possibility no so crazy with more than 1500 exoplanets discovered in the past 20 years.
    Even if its a simple extrasolar icy rock, tracking back its origin could lead us to find brown dwarf stars in the proximity of our solar system yet not discovered.


    • Harry R Ray November 1, 2017, 9:54

      Unfortunately, Arecibo is OFF-LINE due to the damage done to it by Hurricane Maria. The BEST radio observations would be made via interferometry(i.e., Jansky VLA, VLBI, LOFAR, etc.). Oh, and by the way, Breakthrough Listen should ALSO be observing with ATA and Green Bank!!!

      • Harry R Ray November 5, 2017, 17:10

        Updates from Jon Richards regarding observations of A/2017/U1 with ATA. [2017 10-30 01:58:04] Calibrating to observe A/2017 U1, the mysterious object that has entered the solar system. 1 GHz to 2ghz tonight. [2017 10-30 03:29:46] Correction 1GHz to 3GHz tonight. [2017 11-1 01:35:35] Calibrating to observe A/2017 U1, the mysterious object that has entered the solar system. 1GHz to 2GHz tonight, again. GOOD FOR YOU ATA! NOW, COME ON BREAKTHROUGH LISTEN-Green Bank!

  • ljk November 1, 2017, 9:37


    i4is announces Project Lyra: A mission to A/2017 U1, the interstellar asteroid!

    October 30, 2017

    i4is is happy to announce a new project: Project Lyra. Lyra is the star constellation from which the interstellar asteroid A/2017 U1 came from. According to current information, the object is smaller than 400m in diameter and is currently travelling at 44km/s with respect to the sun, much faster than any human-made object to date.

    What can be more exciting than chasing this object with a spacecraft and making observations from a close distance? What secrets are hidden on this visitor from our galaxy? The velocity of the object makes it challenging to reach but this challenge might lead to new, innovative mission concepts.

    After the formation of an internal team, we are now actively seeking collaborators for this project to study mission concepts for exploring the visitor from interstellar space!

  • Michael November 1, 2017, 14:59

    I am not sure planet x could have done it as the inclination is not expected to be that high or could it have.

    • hiro November 1, 2017, 16:35

      If we send 500 trillion “starchips” from this system to the Centauri System, how many of them will come close a distance around 0.25 AU from the main star itself? Passing “close” to a native planet is another problem but let’s assume this rock is natural 100%.

      The real problem is much more difficult since the closest star from that direction is farther than 10 ly away. If this rock is native then the dynamic of this system is more interesting than we normally expect.

  • ljk November 3, 2017, 14:34

    Our close call with an “alien probe”

    Aliens are always the last resort. But once, we thought we might have found an alien probe.

    By John Wenz | Published: Friday, October 27, 2017


    To quote:

    Duncan Steel, an astronomer focused on small solar system bodies, proposed “very tentatively” that it could be an alien probe, saying that in the absence of other explanations, it represented a “candidate for consideration.”

    Robert Freitas and Frank Valdes looked for objects behaving just like this in the 1980s as part of the Search for Extraterrestrial Artifacts, which applied scientific rigor to a science-fiction idea: that a spaceship could be hiding in groups of asteroids near Earth and in the main belt.

    “We reasoned that unless the probes were intended to hide from detection it would be possible to actually look,” Valdes, a scientist at the National Optical Astronomy Observatory, says.

    He adds that the best way to find an alien probe would be to conduct an asteroid-like hunt for them. “This is the same process used for finding asteroids, including potential impacting asteroids,” Valdes says. “The main difference is that these would not whiz by but remain in a stable nearby orbit.”

    Sound familiar?

    Based on its orbit, the object christened 1991 VG was expected to re-encounter Earth earlier this year. And indeed it did — but in that 26-year interim, our understanding of asteroids and meteors improved, as did the sample population of small asteroids like 1991 VG. It turns out, most 10- to 20-meter asteroids tumble like that without falling apart.

    “What [Steel] was suggesting was that we knew how many objects in the 10- to 20-meter size range were out there and we didn’t,” Scotti says.

    Rocket bodies are hollow, and as such, can be pushed around by radiation from the Sun. Their orbits would likely move and shift over time. But 1991 VG was exactly where Scotti and his collaborators predicted on its return in May 2017.

    And as it tumbled through, the intervening years had taught us that this wasn’t an alien probe or a human spaceship: it was just another rock in our neighborhood dropping by for a visit.

    • hiro November 5, 2017, 16:24

      The idea of spaceship hiding inside an asteroid is outdated; a cluster of smart nano-machines (smart matter) inside the core of an asteroid transforming dumb matter into “smarter matter”, the asteroid still looks ordinary from the outside but it’s just a shell only, of course this belongs in the domain of SF for now.

      Anyway, do you think we have capabilities (in the future) send “spacechips” to Proxima Centauri and use it gravitational field to change the trajectories of those probes (assuming they survive the heat) in a way such that those probes will pass close to planet(s) of the main system?

      • ljk November 6, 2017, 10:01

        If we can get a swarm of StarChips to another star system, then I think using any planets there as gravitational assists will be a piece of cake in comparison to the actual journey there.

  • Kolyo November 6, 2017, 10:31

    Taking into account that this visit is probably very very rare it will be an opportunity to visit an object from other stellar system we must not miss! Maybe we will not have such an opportunity in centuries or thousands of years. Maybe these randevous are more often but the calculations shows that they are not. We have the chance, if we organize a pettition to NASA to send a mission to A/2017 U1. There are two possibilities for such a mission. First is more feasible and second will give more precious data. First is to send in the next several months a probe to intersect the orbit of this interstellar object and to make a short flyby near the surface sending precious data, images and spectroscopic measurements. Second more difficult type of mission is to send a probe to chase the object and finally to lend on it. It will need Jupiter gravity assistance to enter into the desired trajectory and than to speed up with aboout 10-11 km/s with ion propulsion system to reach the object, it is achievable only with our current technology, but the cost, probably will be in order of 5-10 billions and we have to show that such a visit is of greatest importance to humanity at the moment than any other mission. I will probably contact planetary society, and ask are they planining to organize such a campaign to force NASA to do such a mission, at least a flyby mission which will be much easier.

    • ljk November 7, 2017, 10:18

      How about other spacefaring nations which may be able to cut through the red tape sooner? Or private industry? With the fact that Elon Musk may put humans on Mars sooner than NASA, I think we need to look at other organizations if we want to get a probe to that interstellar visitor sooner rather than never.

      • Kolyo November 7, 2017, 14:29

        SpaceX is probably the best chance the lunch can be done in affordable manner but the probe building is a quite complex task which can be done only from a space agency that has a solid experience in building and operating such spacecrafts. For now I believe NASA has the best chances to do this, probably with the help of ESA and other partners as well. There only should be a political consensus that this mission is important and I don’t see at the moment such consensus. This event was presented in a very limited number of media and the coverage was really poor. Even if we know as scientists that this event maybe a groundbreaking in interstellar research it will be very difficult to convince general public or even the space agencies lobbies. Unfortunately we are running on limited time to do this, because of the very high velocity of this object. I still believe however it will be a productive endeavor to chase it with all possible resources. Unfortunately if we don’t act quickly in a matter of 2-3 years the object will be unavailable with the current technology.

        • ljk November 7, 2017, 15:03

          With all the insanity, tragedy, and just plain stupidity going on in our society right now – combined with the media’s endless focus on it and a growing anti-science and anti-education attitude – how can something like an interstellar visitor that isn’t even an alien vessel compete?

          I want to say that scientists need to step up and speak out, and I don’t just mean Neil DeGrasse Tyson, but I am not finding myself bowled over by anyone in that profession when it comes to waking up the public and politicians. Even the March on Science doesn’t seem to have made much of an impression other than making supporters feel good temporarily.

          Sorry I had to throw politics and sociology into this mix, but space missions – especially ones involving pure science like this one – do not happen without them.

          Maybe we need some scientists hinting that A/2017 U1 is “behaving” in an “unusual” manner and leave that with the media so they can do their usual rampant speculation and pique the public interest. And change the name to something less dry and academic.

  • ljk November 7, 2017, 15:52

    A/2017 U1 gets another name…


    Sorry Rama fans.

    To quote:

    In a bulletin from the International Astronomical Union Minor Planet Center, Gareth Williams said if the object came from our own solar system, the IAU wouldn’t ordinarily give it a name. But in this case, he wrote, “Due to the unique nature of this object, there is pressure to assign a name.”

    Additionally, the IAU had no designation scheme for an interstellar object. Here’s how they solved both problems:

    A solution has been proposed that solves the problem. A new series of small-body designations for interstellar objects will be introduced: the I numbers. This new sequence will be similar in form to the comet numbering system and assignment of the numbers will be handled by the Minor Planet Center.

    Provisional designations for interstellar objects will be handled using the C/ or A/ prefix (as appropriate), with the designation using the comet system.

    Accordingly, the object A/2017 U1 receives the permanent designation 1I and the name ʻOumuamua. The name, which was chosen by the Pan-STARRS team, is of Hawaiian origin and reflects the way this object is like a scout or messenger sent from the distant past to reach out to us (‘ou means reach out for, and mua, with the second mua placing emphasis, means first, in advance of).

    Correct forms for referring to this object are therefore: 1I; 1I/2017 U1; 1I/ʻOumuamua; and 1I/2017 U1 (ʻOumuamua).

    This first interstellar object is being handled as a special case. A small committee of the WGSBN will be created to codify the circumstances under which an object will qualify for an I-number and the rules that will apply to the names, bearing in mind the precedent set by this case. A formal report will follow their deliberations.

  • Jean Schneider November 8, 2017, 10:03

    1I/2017 U1 now at
    with all scientific papers and updated regularly

  • Michael Fidler November 9, 2017, 23:24

    On a Possible Giant Impact Origin for the Colorado Plateau.

    “It is proposed and substantiated that an extraterrestrial object of the approximate size and mass of Planet Mars, impacting the Earth in an oblique angle along an approximately NE-SW route (with respect to the current orientation of the North America continent) around 750 million years ago (750 Ma), is likely to be the direct cause of a chain of events which led to the rifting of the Rodinia supercontinent and the severing of the foundation of the Colorado Plateau from its surrounding craton.
    It is further argued that the impactor most likely originated as a rouge exoplanet produced during one of the past crossings of our Solar System through the Galactic spiral arms in its orbital motion around the center of the Milky Way Galaxy. Recent work has shown that the sites of galactic spiral arms are locations of density-wave collisionless shocks. The perturbations from such shock are known lead to the formation of massive stars, which evolve quickly and die as supernovae. The blastwaves from supernova explosions, in addition to the collisionless shocks at the spiral arms, can perturb the orbits of the streaming disk matter, occasionally producing rogue exoplanets
    that can reach the inner confines of our Solar System. The similarity between the period of spiral-arm crossings of our Solar System to the period of major extinction events in the Phanerozoic Eon of the Earth’s history, as well as to the period of the supercontinent cycle (the so-called Wilson Cycle), indicates that the global environment of the Milky Way Galaxy may have played a major role in initiating Earth’s past tectonic activities.


  • Martin Seligman December 5, 2017, 23:53

    Isn’t anyone bombarding it with the whole spectrum of wavelengths on the chance it will respond?

  • vannevar bushveld December 12, 2017, 7:36

    many interesting comments about the visitor. the lap around the sun is surprising. on 10.17 at approximately 9:30 pm EST i saw a pair of shooting stars in rhode island. could they have originated from A/2017 U1? the shape of the object and its durability is notable.