‘Oddball’ cigar-shaped interstellar asteroid visits our solar system

First known interstellar visitor is an ‘oddball’, with a very odd and highly unusual aspect ratio.

From the ASSOCIATION OF UNIVERSITIES FOR RESEARCH IN ASTRONOMY (AURA)

In October astronomers were surprised by a visitor that came racing into our Solar System from interstellar space. Now, researchers using the Gemini Observatory have determined that the first known object to graze our Solar System from beyond is similar to, but definitely not, your average asteroid or comet. “This thing is an oddball,” said Karen Meech of the University of Hawaii’s Institute for Astronomy who leads an international team studying this interstellar interloper.

Originally denoted A2017 U1, the body now goes by the Hawaiian name ‘Oumuamua, in part because of its discovery by Meech’s team using the Pan-STARRS1 survey telescope on Haleakala in Hawai’i. When discovered in mid-October ‘Oumuamua was only about 85 times the Earth-Moon distance away and its discovery was announced in early November.

Since its discovery ‘Oumuamua has faded from view. The object’s rapidly increasing distance from the Earth and Sun now makes it too faint to be studied by even the largest telescopes.

“Needless to say, we dropped everything so we could quickly point the Gemini telescopes at this object immediately after its discovery,” said Gemini Director Laura Ferrarese who coordinated the Gemini South observations for Meech’s group.

“What we found was a rapidly rotating object, at least the size of a football field, that changed in brightness quite dramatically,” according to Meech. “This change in brightness hints that ‘Oumuamua could be more than 10 times longer than it is wide – something which has never been seen in our own Solar System,” according to Meech.

‘Oumuamua shares similarities with small objects in the outer Solar System, especially the distant worlds of the Kuiper Belt – a region of rocky, frigid worlds far beyond Neptune. “While study of ‘Oumuamua’s colors shows that this body shares characteristics with both Kuiper Belt objects and organic-rich comets and trojan asteroids,” says Meech, “its orbital path says it comes from far beyond.”

The research led by Meech is published in the November 20th online issue of the journal Nature.

‘Oumuamua was visible from Chile and Hawai’i so both Gemini North and South telescopes were on high alert and ready to track the visitor from outer space. “We observed from both sites for three nights, before it sped away and faded from view,” said Ferrarese. Two additional teams obtained data from Gemini North and their results are currently pending publication.

According to our current understanding of planetary system formation, our Solar System ejected comets and asteroids due to interactions with the larger outer planets. It is presumed that other planetary systems do the same and that these visitors might be more common than previously thought. “We estimate that there is always one of these objects of similar size as ‘Oumuamua between the Earth and the Sun at any given time, so up to about 10 per year,” says Robert Jedicke also on Meech’s team.

“These observations allow us to reach into another planetary system to learn about one of its rocky bodies, and compare this object with the asteroids we know throughout our own Solar System”, says Faith Vilas, the solar and planetary research program director at the National Science Foundation who helped support this research.

Surveys like Pan-STARRS and the future Large Synoptic Survey Telescope (LSST, currently under construction near the Gemini South telescope in Chile) will undoubtedly increase the detections of these interstellar wanderers.

“The discoveries of rare surprises like ‘Oumuamua from outside our Solar System will be greatly accelerated by the power and grasp of the LSST,” said Richard Green of the US National Science Foundation (NSF). “LSST is going to produce a torrent of data and revolutionize this sort of time domain astronomy when it begins operations early in the next decade,” adds Green. LSST is funded by a partnership with the NSF, the Department of Energy, and the LSST Corporation.

‘Oumuamua loosely means “a messenger that reaches out from the distant past,” fitting the nature of the object’s interstellar origin. In Hawaiian ‘ou means “to reach out for,” while mua means “first” and is repeated for emphasis.

###

The paper: A brief visit from a red and extremely elongated interstellar asteroid

https://www.nature.com/articles/nature25020

Abstract:

None of the approximately 750,000 known asteroids and comets is thought to have originated outside our Solar System, but formation models suggest that orbital migration of the giant planets ejected a large fraction of the original planetesimals into interstellar space1. The predicted interstellar number density2 of icy interstellar objects of 2.4 × 10−4 au−3 suggested that these should have been detected by surveys, yet hitherto none had been seen. Many decades of asteroid and comet characterization have yielded formation models that explain the mass distribution, chemical abundances and planetary configuration of today’s Solar System, but until now there has been no way to tell if our Solar System is typical. Here we report observations and subsequent analysis of 1I/2017 U1 (‘Oumuamua) that demonstrate the extrasolar trajectory of ‘Oumuamua. Our observations reveal the object to be asteroidal, with no hint of cometary activity despite an approach within 0.25 au of the Sun. Spectroscopic measurements show that the object’s surface is consistent with comets or organic-rich asteroid surfaces found in our own Solar System. Light-curve observations indicate that the object has an extreme oblong shape, with a 10:1 axis ratio and a mean radius of 102±4 m, assuming an albedo of 0.04. Very few objects in our Solar System have such an extreme light curve. The presence of ‘Oumuamua suggests that previous estimates of the density of interstellar objects were pessimistically low. Imminent upgrades to contemporary asteroid survey instruments and improved data processing techniques are likely to produce more interstellar objects in the upcoming years.

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121 thoughts on “‘Oddball’ cigar-shaped interstellar asteroid visits our solar system

    • TheLastDemocrat
      November 21, 2017 at 12:20 pm

      Yes…it’s just an artist’s impression. It is much too far away to get an image.

      As I understand it (as an amateur astronomer only) the shape is deduced from the extreme change in brightness as it rotates every 7 hours or so. However, it could equally be a circular object with one side very bright and the other very dark. Quite unusual perhaps…but some solar system moons do have bright and dark sides.

      A bit like climate (non)science…you jump to the most dramatic idea…gets lots of interest which helps greatly with funding. Or am I being unkind?

  1. It’s rotating to provide artificial gravity to the explorers inside …

    Can Hubble be used to take a closer look at things like this?

  2. Paraphrasing somewhat…”That’s no asteroid, it’s a SPACESHIP!”

    But yeah, probably being drawn closer to Earth by those human CO2 emissions, so definitely our fault. /sarc

    • If it is 10 times longer than it is wide, it could be the “Sentinel”, another of Arthur C Clarke’s creations. The sentinal’s proportions were 9 x 4 x 1, that is 3 squared by 2 squared by 1 squared.
      If, as the report says, it by-passed us and is heading away, we are obviously not worth bothering about.

  3. Artistic license with the picture.
    If this happens once in our lifetimes it is not an uncommon event so how many of these things are out there.

  4. I thought I could see a faint, spherical atmosphere surrounding the middle 20% of it; undoubtedly, it should be tested for water and see if life has ever existed on it! Or not . . .

  5. If it was an alien spaceship attracted by our radio signals they were about to make contact and then overheard Al Gore talking about climate change, decided Earth had no intelligent life and went on their way.

  6. How do we not know that it originated from our own solar system 4 billion yeas ago, and is a new class of asteroid and/or comet that is now double orbiting another nearby solar system with our own? Too bad we couldn’t land a small nuclear powered radio telescope/transmitter that could communicate with Earth for centuries to come, and would give us a front row seat to interstellar space and where it is going. Fascinating!

    • Well…

      I’d say we’d be better off creating a nuclear powerd drive and sending it where we want. It would end up going much faster, and somewhere interesting. Most of space is nothing at all, in fact statistically space is completely empty (and any planets and inhabitants you may see from time to time are probably figments of your imagination).

      Even a solar sail would get to a faster speed, I suspect.

      • You might like to retink that.
        Have you seen how fast it was travelling before it got the slingshot and how fast it is now?
        Coming in at 15Miles/Sec (54,000Mph) sped up to 27Miles/Sec (97,200Mph) with the slingshot affect.

      • Acceleration beats velocity hands down. When you are talking traveling 10 or 100 light years (and less gets you very few places) speed is not a factor, only acceleration.

        You can get to a significant fraction of light speed even with a solar sail if large enough, I think. That was from sci fi, but an author whose science i trust.

      • And as a comparison, we are moving around the sun at 30 km a second, and probably 360 km a second away from the ‘center’ of the universe. Perspective is useful (but can be dangerous as the Total Perspective Vortex proved).

  7. Well Well, something else accepted science knew nothing about.

    I wonder what else there is they know f*ck all about.

  8. So let me get this ABSOLUTELY straight…once and for all….
    ‘astronomers’ are ‘unsure’ of how many ‘planets’ we have in our solar system BUT they have have somehow spotted and tracked an object the size of an oil tanker entering our solar system from ‘interstellar space’?
    Is that right?

    • Luckily they had their eyes peeled or they would have missed this asteroid. Closer to earth ‘cigar shaped UFO’ are more common.

    • –So let me get this ABSOLUTELY straight…once and for all….
      ‘astronomers’ are ‘unsure’ of how many ‘planets’ we have in our solar system BUT they have have somehow spotted and tracked an object the size of an oil tanker entering our solar system from ‘interstellar space’?
      Is that right?–

      We have have an under funded government program that searches for space rocks that could hit
      Earth [and possibly kill millions of people]. And the “Pan-STARRS1 survey telescope” is one of major telescopes which do this:
      https://cneos.jpl.nasa.gov/
      https://cneos.jpl.nasa.gov/stats/site_all.html
      Look at graph on second link, the light purple is Pan-STARRS1 and it’s finding about 1/2 of the ones being found [that’s what I mean by one of “major telescopes”
      So Pan-STARRS1 is designed to look at a wide sky and find dim objects somewhat close to earth [the space rocks that may come back and hit earth]. So this interstellar rock came fairly close to Earth and Pan-STARRS1 found it and tracked it. Then got on the phone to let the really big telescope top look at it. The really big telescopes are normally looking at distant galaxy or say extasolar planets or whatever. Or they don’t look for space rocks- they not designed to look for them- but if given coordinates, then they can point at them…

    • This object came within 0.2 AU of the sun, where the escape velocity is 42 km/sec. At that point, the asteroid was going 87.7 km/sec. So, yeah, it’s absolutely certain that this came from elsewhere.

      The disturbing thing is that it came out of nowhere, from a direction we wouldn’t necessarily be looking (its inclination to the ecliptic was 123 degrees), it was huge, and it was going way faster then any asteroid in our solar system. Had it hit us, we wouldn’t be writing these comments.

      This has me more than a little shaken.

      • The Sun does rotate around the galactic core, so shouldn’t we be looking in the direction that the sun is heading? I’m assuming this thing is headed in the opposite direction that we are going. Sagittarius is rotating in the opposite direction from Orion, so we very well could see more of these.

        Of course we live in a pretty awesome solar system. Yay us. We rotate around the Sun so at least half the year we would be either shielded by the Sun or moving away from these types of objects. The two outer Giants are also more likely to be hit than Earth, just based on size, so that’s a bonus.

    • What is really great about Wikipedia is that it has the plot summaries of all of the SiFi novels you read 50 years ago, and can no longer remember.

  9. “The discoveries of rare surprises like ‘Oumuamua from outside our Solar System …”

    “None of the approximately 750,000 known asteroids and comets is thought to have originated outside our Solar System, but formation models suggest that orbital migration of the giant planets ejected a large fraction of the original planetesimals into interstellar space”

    So, it appears to me that it’s total BS to speak of knowing this thing came from another star/planet system, since there’s no possible way to know exactly where each of the hypothetical “large fraction of the original planetesimals” were hypothetically ejected “into interstellar space” . . billions of years ago. I read this whole this as a dorky advertisement for continued funding . .

    “Now, researchers using the Gemini Observatory have determined that the first known object to graze our Solar System from beyond …”

    “We estimate that there is always one of these objects of similar size as ‘Oumuamua between the Earth and the Sun at any given time, so up to about 10 per year”

    Oh, what a coincidence that “we” estimate they are rather common, and that “we” figure this thing is one of them . . as the “models” (AKA fantasies) projected ; )

    “The predicted interstellar number density2 of icy interstellar objects of 2.4 × 10−4 au−3 suggested that these should have been detected by surveys, yet hitherto none had been seen. Many decades of asteroid and comet characterization have yielded formation models that explain the mass distribution, chemical abundances and planetary configuration of today’s Solar System, but until now there has been no way to tell if our Solar System is typical.”

    Still is no way, even if this shard is assumed to come from “beyond”, if it’s the only one that’s been observed, OBVIOUSLY.

    I’d fire the top people behind this BS, to set an example for the kids whose minds they are helping turn into mush with such crap logic.

    • JohnKnight
      November 21, 2017 at 1:51 pm

      I agree with the finding bit you mention.

      However I think the other planetary system origin idea results from the hyperbolic orbit it has…all things in our solar system have roughly circular or slightly elliptical orbits (our planets) or extremely ellipitical or parabolic orbits (comets). A hyperbolic orbit suggests it has interacted with a star other than the Sun at some stage in it’s long distant past. The hyperbolic orbit alone makes this object extremely unusual and interesting.

      • The object could have interacted [another] distant object in your solar system and have other kind of interaction within our solar system, but it seems to me it most likely to came from another star system. The lack of this object not being comet make me think it’s been in intergalactic space for quite a while..

      • Alastair,

        “A hyperbolic orbit suggests it has interacted with a star other than the Sun at some stage in it’s long distant past”

        Yeah, “suggests”, and I was reacting to the “first known object to graze our Solar System from beyond” yimmer yammer in the news piece . ,. but if many objects were ejected from the system through interaction with other objects, then an object could be “returned” via interaction with one or more of it’s fellow . . ejectoids ; ) or distant orbitoids ; ) or alien ejectoids ; ) . . and there’s also the remote possibility that we’ve effectively “lapped” it (or vice versa) in our “orbiting” around the galaxy since it got flung out there . .

        Thanks for the check.

      • A hyperbola isn’t a closed geometric form? This thing (probably) hasn’t been through these parts before and isn’t coming back — ever —unless it interacts with something that alters its trajectory?

    • “None of the approximately 750,000 known asteroids and comets is thought to have originated outside our Solar System”

      is thought, ie, clear the obfuscation and they have no flipping idea but want to try sound informed

    • and yes JohnKnight, this article is full of bollocks dressed up as some sort of knowledge.

      Ugh astronomy is full of complete bunk

  10. I propose that we name the oddball cigar-shaped asteroid “William Jefferson Clinton”, in “honor” of our 42nd President.

    • TA November 21, 2017 at 2:42 pm :

      I suspect that it’s probably because they are drawn into the inner solar system by the Sun’s gravity…it just happens that we live in that neighbourhood also! It also wasn’t really that close…inside the orbit of Mercury (at 0.25 AU) so much closer to Mercury and Venus than us.

    • Unless we know how many asteroids there are in interstellar space, it’s impossible to say what the odds are.

      • We would also need to know their velocity vectors. But–if we knew what and where they were and how they were moving, prediction of their motion would be deterministic and not a matter of odds at all. Probability is a misapplied concept in this case.

  11. the shape is hardly surprising, surely asteroids come in all shapes and forms.

    Just cos we ain’t seen one yet, which is also hardly surprising.

    • Mark – Helsinki
      November 21, 2017 at 3:19 pm

      Yes, that’s right. There’s lots of dumbell shaped things out there too…mostly comets so far but maybe asteroids too. They could have unusual and highly variable reflectivity upon rotation. This could even be a “dead” comet which got rid of most of its volatiles when near to another star before being flung our way.

      We need to keep in mind that the actual shape is highly speculative depending on the uniformity of its albeido…which we don’t know. See also my comment at the top of post @12:45

      So many questions, so few answers. Isn’t the universe wonderful!

    • I think that the idea is that if it had been floating around our solar system for 5 billion years, it would have had some collisions that would have made it less long and skinny.

      • Jeff in Calgary
        November 21, 2017 at 4:06 pm

        I agree but, to me at least, it’s a bit hard to imagine just how it could have got that cigar shape. So I like the idea of a more or less circular/elliptical/dumbell body with extreme albeido variations better!

        Yes, I know it’s not nearly as exciting as a cigar!

  12. It raises another point about life on other planets.

    You have to be in a quiet part of the galaxy where there are not asteroids coming in at huge speeds, where supernova are not going off all the time and where your own solar system does not have lots of asteroids and comets at 20 km to 50 km across, coming in every 100 million years.

    It is only takes the speed of one interstellar asteroid, or the speed of one 20 km across comet or one close supernova and the life on your planet is wiped out.

    Earth has not been hit by one of these in at least 3.8 billion years.

      • 10 kms.

        There were two or three 5 km asteroid strikes about 33.5 million years ago.

        Vredefort (2.0 billion years ago) and Sudbury (1.8 billion years ago) were also caused by 10-12 km asteroids. So those are the biggest along with Chicxulub.

  13. As it hits earth’s atmosphere, it will get extremely hot. It will then hopefully “lance the boil” to drain the pustule that is in Washington D C.

  14. Well this thread sure has rarified science/m^2.

    In a modest attempt to interrupt this scintillating discussion of space stools and Lewinsky probes, here … I just finished watching this interesting talk by electrical engineer Donald Scott …

    A TRANSISTOR ANALOGY OF THE SUN’S SURFACE

    (I can already hear Leif’s footsteps coming down the hall. And I don’t think he’s pleased.)

    • Good. A little long, but cogent. This model makes even more sense with the insight from Laszlo Kortvelyessy, that the sun is a thermionic emitter of electrons. When electrons and positive ions (protons) are in thermal equilibrium at the photosphere, the electron speed is 42 times that of the proton speed. A Boltzmann distribution of speed means that there will be electrons that attain escape velocity, both against the gravitational field and the electric field of the sun—and depart the sun. This leaves the sun with an ever-accumulating positive charge. So, Ralph Juergens’ model is correct, but for an open circuit, not a closed circuit. Kortvelyessy has further interesting things to say about the electrical physics of the sun (http://www.electric-sun.info/main.html).

  15. There are several possibilities about this.

    1- It;s a Farseeum scout ship. They came, they saw, they said ‘no way, Jose,’ and left.

    2 – It could be a scout for the Vogon constructor fleet. They’re always behind schedule, anyway.

    3 – It was the Mommy of that chunk of rock that blasted its way through Siberia about 18 months or so ago and shattered windows, damaged buildings, set off car alarms, and buried itself in the frozen ground. That one had a cousin, the one that lit the sky over Finland a week or so ago. Mom’s just looking for her lost children.

    4 – It could be the ‘moon’ that was supposed to hit Venus, increase its revolution speed to 22.5 hours/day by whacking it, and clear away the sulfur clouds.

    5 – It’s one of the moons orbiting the planet Zyra, which imperiled all of Earth in ‘When Worlds Collide’, when the rogue star Bellus came wandering through our solar system.

    • If I wanted to probe an inhabited system without being caught at it, I might well build my probe to look like a natural rock. Of course even if the probe didn’t give itself away by accelerating while under observation, it probably would emit too much heat, thus giving itself away if we’re looking closely enough. Are we?

  16. ‘When discovered in mid-October ‘Oumuamua was only about 85 times the Earth-Moon distance away’

    “its orbital path says it comes from far beyond.”

    They know where it is going; they don’t know where it came from. Color me skeptical. Actually, color me cynical. Declaring it extra solar system when they know interaction with planets can produce the noted orbit is junk science.

    • It’s not junk science – the asteroid came in from above the solar system more or less straight toward the sun and never went anywhere near the gas giant planets. It’s leaving in a similarly high inclination trajectory. They know this, by back-projecting the orbit (they also have some ‘pre-discovery’ images made accidently by other large survey telescopes so have a good set of fixes on it) via standard Newtonian mechanics.

      Thus the approach orbit and the departure orbit are pretty much free from any interaction with a planet that could influence the eccentricity and turn it hyperbolic. There have been solar system objects disturbed by the gas giants that have been given hyperbolic escape trajectory out of the solar system, but this isn’t one of them.

      Nor could a past encounter with say, Jupiter have put it on a very high inclination orbit so it was just returning to this solar system – it’s orbit was hyperbolic, it had too much velocity wrt to our solar system to be a returning solar system asteroid.

      • Andy, exactly right.

        The observed orbital track of this object precludes any possibility that this object was attached to our Sun/solar system in any way prior to this encounter. In fact, a recent paper on the kinematics notes that it cannot have been gravitationally bound to any of the dozen closest star systems to us, the Sun included.

        While there is mathematical speculation as to where it might have come from, none of that can be proven for certain at this point due to lack of evidence. Thus, we don’t really know where it initially formed, nor the complete path it took to get from [wherever that was] to us here. However we can know for sure that it didn’t pass any major objects (e.g. Jupiter or Neptune) on the way in from the dark, and that it’s for sure (beyond reasonable doubt, anyway) not “one of ours” thanks to the object’s current vector & observed track.

        https://arxiv.org/pdf/1710.11364

    • Or it was kicked out from the solar system millennia ago, and finally circled back.

      It’s origin is unknown. Meaning it is unknown.

      • Gamecock, with respect, the answer to your statement is, “No, it simply was not; mathematically, it cannot have been, regardless of the passage of millennia, or even ‘bill-ennia’.” You earlier said “they know interaction with planets can produce the noted orbit…” This is the opposite of the truth, & the source of my answer: there is NO known interaction nor series of interactions w/our system, nor with those of the nearest stars, which can produce the observed orbital ephemeris, as the paper I linked demonstrates.

        If you are still not convinced, that’s okay, just understand that scientifically your position — an assertion which runs contrary to the available evidence, rather than with it — is fairly unpersuasive at this point. That would likely change were evidence to be presented that such interactions WERE possible, but none has been forthcoming to this point; if you have some to share, that would no doubt be welcome information in many scientific circles.

        Fwiw, I agree that we don’t know where ‘Oumuamua came from, nor exactly what it is, nor where/how it formed; it is in large part unknown, & will remain that way for a long time at least. However it is the observational evidence we currently DO have which demonstrates pretty doggoned conclusively that it was not formed anywhere near our system… unless you’re counting “The Milky Way Galaxy” as “near,” which I suppose is reasonable from a certain point of view/scale.

  17. The hyperbolic orbit is necessary and sufficient to identify this object as a one-time visitor to our system, but it is NOT unique. Any orbit with an eccentricity ε greater than 1.0 is a hyperbolic orbit, and is one that will take the object away from the sun forever – if it survives perihelion and does not by chance encounter any planets closely enough to have that hyperbolic orbit perturbed.
    Wiki lists over 300 comets with orbital ε greater than unity. Others with listed orbital ε equal to unity may be hyperbolic, parabolic, or elliptical with VERY long periods and semi-major axes. The uncertainty in the determination of the orbital elements is large enough that a definite classification can not be made.
    https://en.wikipedia.org/wiki/List_of_hyperbolic_comets
    This body is not unique in being a stranger to our solar system. What is different about this body is that it appears to be non-cometary – the material is not volatile.

    • Good comment, tadchem,

      Not to dispute, but rather to add to said comment, I would point out that of those comets listed in your provided link only 2 have an eccentricity above 1.01: C/2008 J4 McNaught (1.028), and C/1997 P2 Spacewatch (1.0281). Most have eccentricities below 1.001, & although they are escape trajectories, they could very plausibly have been made so via gravitational &/or collisional interaction w/local objects (the Sun, major planets, other Oort Cloud objects, etc.). In other words, though their current paths are hyperbolic & certainly will escape the solar system unless somehow interfered with, it’s entirely plausible that most of them (if not all) actually did form in concert with the Sun & its system prior to their one & only observed fly-by.

      By contrast, the eccentricity of A/2017 U1 ‘Oumuamua is 1.192, far greater than any of the known hyperbolic comets. Unlike the orbits of those comets, this orbit could not plausibly have been pulled/pushed into that shape on its initial approach by potential interactions involving the other objects of our solar system… or indeed, as the paper I linked above alleges, with those of any of the dozen closest star systems to our sun. Thus, while a few of the hyperbolic comets listed might “likely” or “plausibly” have been interstellar visitors on their way into the solar system (& ALL of them are on interstellar paths on the way out), ‘Oumuamua’s distinction is that it is the first such object we have observed which virtually “must” be interstellar in origin, unbound & unrelated to our solar system or its formation when it arrived.

      As such, even the science-minded & well-educated (let alone the general media, lol!) may be forgiven for calling it “the first observed interstellar object” without requiring too terribly much in the way of skepticism or correction; in this case, they probably (“probably,” I say) aren’t far wrong. Regardless, its orbit is certainly the first we have observed with such a blatantly interstellar ballistic trajectory, and as you pointed out tadchem, is also the first which appears so clearly non-cometary despite its orbital eccentricity.

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