[HN Gopher] Astronomers race to study interstellar interloper
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Astronomers race to study interstellar interloper
Author : bikenaga
Score : 87 points
Date : 2025-07-11 15:43 UTC (7 hours ago)
(HTM) web link (www.science.org)
(TXT) w3m dump (www.science.org)
| TheBlight wrote:
| Vera Rubin isn't even giving us data dumps yet. It's going to be
| like a veritable firehose of interstellar object detections.
| Should be a wild time for the field.
| k__ wrote:
| I hope this will end better than in Outer Wilds.
| OneDeuxTriSeiGo wrote:
| LMAO. That was the exact immediate reaction I had as well. The
| outer wilds brain rot is truly inescapable.
| rtkwe wrote:
| On a similar vein there's Project Lyra which is a theoretical
| fly-by mission of `Oumuamua or 2I/Borisov. The proposed
| trajectories to catch up are pretty crazy with my favorite being
| the 2030 launch for a 2052 fly-by that uses Jupiter and a close
| Sol 10 solar radii!) gravity assist to rocket out of the solar
| system [0].
|
| It will be interesting to see if we've just been missing these
| extra solar objects. I have doubts we'll actually do a project
| Lyra style fly-by though. Funding is going the opposite direction
| and all.
|
| [0] http://orbitsimulator.com/BA/lyra.gif and
| https://i4is.org/project-lyra-a-solar-oberth-at-10-solar-rad...
| jerf wrote:
| I'd expect this is just the lamppost effect and we'll start
| seeing lots of these. It means there's no great need to chase
| any particular one of them, we can almost certainly wait until
| we're ready, then pick one that is convenient at the time.
|
| It also means that "Oumuamua is an alien craft!" will almost
| certainly join in the ignoble legacy of "thinking the first
| instance of a new thing must be ALIENS" once we've detected
| hundreds of these (or more, depending on how sensitive we can
| get). You'd really think we'd be over this by now, but
| apparently not.
| __MatrixMan__ wrote:
| If we ever stop being excited about the possibility that
| poorly understood phenomena are evidence of undiscovered
| intelligent life the we'll have lost a part of our humanity.
| pfdietz wrote:
| That's just bullshit. The idea that undiscovered
| intelligent life is a plausible explanation for such things
| is just the triumph of numerically illiterate wishful
| thinking over rational thought.
| __MatrixMan__ wrote:
| I'm not saying that it's a conclusion that we should jump
| to. Just that it's silly to expect people not to consider
| it first. It's more related to why we're looking up in
| the first place than any of its alternatives.
| pfdietz wrote:
| It's so ridiculous that the only reason to expend a
| single keystroke on it is to demolish it.
|
| Consider what the implication would be if these are ET
| spacecraft. The galaxy would be absolute _soaked_ in ETI.
| The Fermi argument would then bite maximally: why did we
| even evolve, if the galaxy has been so saturated? Why
| wasn 't every single planet and asteroid used for
| colonies and resources ages ago?
|
| It's important to realize that science fictional tropes
| of galaxies with everyone zooming around in spaceships
| having adventures are not consistent with what we
| observe.
| __MatrixMan__ wrote:
| What does the low probability have to do with it?
|
| If you had asked Galileo's contemporaries about the
| probability that he'd find moons orbiting Jupiter, they'd
| have put it at zero, and they turned out to be wrong.
|
| Einstein's work was also in flagrant disregard of the
| established scientific sensibilities of the time.
|
| I can't speak for everybody, but the excitement that I
| get when I look through a telescope, or a microscope, or
| commune with any machine that can see something that I
| can't... it comes from the possibility that I'll see
| something impossible, something that invalidates the
| theories which previously governed what I'm likely to
| see. It's why we keep building better telescopes and
| bigger particle colliders--because we want to prove
| ourselves wrong.
|
| It's fine to be a rationalist with an appreciation for
| existing theory, but it's not irrationality when others
| attempt to invalidate what you're protecting--thats where
| progress comes from. We wouldn't know as much as we do
| without the people who look for things that shouldn't be
| there on the basis of viewpoints outside of accepted
| theory.
| MarkusQ wrote:
| I remember the first time I heard of that pattern of
| thinking. My initial reaction was "OMG, it must be aliens!"
|
| Then I thought "now wait a minute...hold on..."
| rtkwe wrote:
| It's not so much a matter of being ready, it's a matter of
| what planets are where that we can get a boost out of to get
| those speeds. Even with a fleet of working starships and
| assembling something in orbit getting up the to speed of
| these extra solar objects practically requires some intense
| maneuvers near conveniently positioned and timed planets.
| dbingham wrote:
| Please correct me if I'm wrong, but my understand of the
| alien craft theory specifically for Oumuamua wasn't just
| because the object itself was new, but that it changed
| acceleration [1] without apparent off gassing in a way that
| isn't explained by our current understanding of orbital
| physics for a natural object.
|
| It's not just "New object, must be aliens!" It's "This thing
| doesn't fit our understanding of orbital motion for natural
| objects, aliens is actually a rational, if still unlikely,
| possible explanation."
|
| [1] https://en.wikipedia.org/wiki/1I/%CA%BBOumuamua#Non-
| gravitat...
| ryanblakeley wrote:
| There were a number of anomalous characteristics including
| its shape, acceleration, rotation, origin, and
| reflectivity.
| ceejayoz wrote:
| How do we know they're anomalous characteristics if it's
| literally the first one we've ever spotted? What is the
| _normal_ shape of an interstellar comet core?
| cubefox wrote:
| For example, being flat like a pancake is obviously
| highly unusual and very different from anything we have
| seen from stellar comets.
| ceejayoz wrote:
| Stellar comets haven't been ejected from another solar
| system. We have vanishingly few examples of those, and
| we've not directly observed any up close.
|
| "Flat as a pancake" is one of _several theoretical
| possibilities_ from its light curve, not a known fact
| about the object.
|
| "Highly unusual" in space tends to mean "there are a
| bunch, but we haven't seen them until now". In 1992,
| exoplanets were "highly unusual". Now they're everywhere.
| cubefox wrote:
| The highly unusual properties are such that they are
| genuinely hard to explain for astronomers. See my
| neighbouring comment.
| TheBlight wrote:
| The same as the ones from this system. Borisov had the
| same characteristics.
| ceejayoz wrote:
| > The same as the ones from this system.
|
| Why would we assume non-interstellar comets are always
| the same as interstellar comets? Conditions obviously are
| a little different when something is ejected from a
| system and then spends millions of years in interstellar
| space.
|
| > Borisov had the same characteristics.
|
| We have a sample size of three thus far. Making
| conclusions right now is like saying all extrasolar
| planets are large gas giants because the first three
| were.
| jerf wrote:
| The history of science is that _every freaking time_ we
| look somewhere new, we find something new. It happens over,
| and over, and _over_ , and _over again_. We have a really
| bad track record of predicting things in advance in new
| domains. The exceptions are leaping to your mind precisely
| because you 've heard about them because they're the
| _exceptions_.
|
| Also, to date, zero of those things have been "aliens".
|
| So rushing to declare the first instance of what was
| completely obviously a new class of objects as "aliens"
| because it didn't behave like what we expected is not
| rational, because we should _expect_ that new things don 't
| behave like we expect. The odds that the first one of these
| we detect is also the one from aliens is just not a good
| bet.
|
| I'd bet a tidy sum of money that in 25 years it'll simply
| be common knowledge that these class of objects sometimes
| have those characteristics because of some characteristic
| special to them. Probably something to do with having a lot
| of things that turn to gasses and exert accelerations on
| the object because they were never blown off by the solar
| wind or something because of them being in deep space for
| millions of years. Might be most of them, might be a small-
| but-respectable fraction, but I bet in hindsight this is
| recorded in the history books right next to "pulsars are
| alien beacons!" and with the exact same tone of lightly
| sneering contempt we hold for that now. To which I can only
| say to the future, let the record show we did not all think
| it was aliens.
| mellosouls wrote:
| Yes (a change in acceleration was reported), but even in
| the link you yourself provide the hypotheses are framed
| within standard physics, not alien technology.
|
| The latter got more than its fair share of press because
| Harvard's Avi Loeb proposed it as potential evidence of ET.
|
| He later claimed more evidence from potential spaceship
| bits he reckons he found from an ancient meteor, and seems
| to specialize in these sorts of claims. [1]
|
| Like you say, not irrational but perhaps over-hyped by
| people who ought to know better...
|
| [1]https://www.independent.co.uk/news/world/americas/avi-
| loeb-i...
| cubefox wrote:
| > It also means that
|
| No, it doesn't mean that. What makes 'Oumuamua special is
| _not_ the fact that we didn 't see interstellar objects
| before. It's rather the fact that 'Oumuamua has highly
| unusual and hard to explain properties. Avi Loeb:
|
| > 'Oumuamua exhibited a non-gravitational acceleration of
| 4.92 +- 0.16 x 10^-6 m/s2 that decreased proportionally to
| 1/r2, where r represents the heliocentric distance,
| corresponding to a formal ~30 s detection of non-
| gravitational acceleration (Micheli et al., 2018). The
| inverse-square relationship typically indicates radiation
| pressure or outgassing forces. However, despite extensive
| observations by the Spitzer Space Telescope, no carbon-based
| molecules, dust, or thermal emission indicative of cometary
| outgassing were detected (Trilling et al., 2018). Such a
| paradox -- acceleration without observable mass loss --
| violates fundamental assumptions about how small bodies
| behave in the solar system.
|
| > The object's extreme geometry presented another
| unprecedented observation. 'Oumuamua's brightness varied by a
| factor of 10 during its 8-hour rotation period, indicating an
| extreme geometry with an aspect ratio exceeding 10:1 (Drahus
| et al., 2018; Meech et al., 2017). Such extreme elongation is
| unprecedented among known Solar System objects, leading to
| competing interpretations of either a cigar-shaped or
| pancake-like geometry (Belton et al., 2018; Luu et al., 2020;
| Mashchenko, 2019; Moro-Martin, 2019a,b; Zhang & Lin, 2020).
|
| > More significantly, 'Oumuamua entered the Solar System with
| a velocity remarkably close to the Local Standard of Rest
| (LSR). The object's velocity before encountering the Solar
| System was within approximately 6 km/s of the local median
| stellar velocity and just 11 km/s from the LSR, with
| negligible radial and vertical Galactic motion (Mamajek,
| 2017). Fewer than 1 in 500 stars share such kinematics,
| making 'Oumuamua's near-stationary approach highly improbable
| for a naturally ejected object from a nearby star system
| (Loeb, 2022). Natural ejection mechanisms from planetary
| systems typically impart the host star's peculiar velocity to
| expelled bodies, yet 'Oumuamua appeared to originate from the
| most kinematically common frame of reference in our Galactic
| neighborhood (Loeb, 2022; Mamajek, 2017).
|
| > The object's rotational dynamics added another layer of
| complexity. 'Oumuamua displayed non-principal axis rotation,
| exhibiting a tumbling motion rather than spinning around a
| single axis. Such a rotational state is unusual for an object
| that has been traveling through interstellar space for
| potentially billions of years, as collisions and internal
| friction should have damped its motion to simple rotation
| (Belton et al., 2018; Fraser et al., 2018).
|
| > Finally, the object's slightly red color differed from both
| typical comets and asteroids. Its spectral properties showed
| no absorption features that would indicate specific mineral
| compositions, making it difficult to determine its definite
| surface composition (Jewitt et al., 2017; Ye et al., 2017).
| This spectral ambiguity prevented researchers from
| determining surface composition through standard techniques,
| leaving the object's fundamental nature -- rocky, icy, or
| something else entirely -- unresolved.
|
| https://avi-loeb.medium.com/scientific-paradigm-
| resistance-e...
| ceejayoz wrote:
| Avi Loeb got trucks mixed up with aliens, then proudly
| announced he'd found a chunk of alien metal in the ocean
| based on that mistake.
|
| https://news.climate.columbia.edu/2024/04/09/was-it-an-
| alien...
|
| > The signals consisted of so-called Rayleigh waves, high-
| frequency motions that travel on or just under the surface,
| and die out quickly as they radiate from their source.
| These can be generated by earthquakes, but also by human
| activities, including explosions, electrical signals and
| vehicles. The sources of these ones seemed to be moving,
| not stationary. Moreover, they appeared in a definite
| pattern: several per hour, almost invariably between 5am
| and 11pm local time.
|
| > The team checked a Google Earth map showing the
| seismometer and its environs. It was just off the main road
| to the harbor, near the Manus Navy Health Center. The
| center seemed to be a locus of activity, with the signals
| moving back and forth from it, southwest to north--the same
| orientation as the road. Ekstrom's conclusion: the
| seismicity was coming from trucks bumping along the
| irregular surface of the road, mostly in daytime, stopping
| at the health center to deliver or pick up people or
| supplies, then going back where they came from. That
| included the purported tremor from the meteor explosion.
|
| https://www.independent.co.uk/news/world/americas/avi-
| loeb-i...
|
| "Fewer than 1 in 500 stars share such kinematics" means
| 200+ million in our little galaxy alone.
| api wrote:
| Rendezvous with one of these would be a good use for a NERVA-
| type nuclear engine (upper stage, not used in the atmosphere).
|
| Also seems like the thing to do, given that we are finding more
| than one of these now, is to build such a thing and have it on
| standby and look for one that's inbound so we can launch at the
| best window to reach it.
| rtkwe wrote:
| Even with a NERVA engine it's a LOT of work to get to the 26
| kmps of an object like `Oumuamua so you're still at the mercy
| of planets being in roughly the right locations to provide
| some gravity assists. I think it would widen the workable
| solutions but something like the 10 SR assist could work with
| things we've actually built already.
| m4rtink wrote:
| Solar Oberth manuever FTW! :D
|
| The High Frontier board game from Phil Eklund even has it as a
| valid option on its orbital map of the Solar system. :)
| pfdietz wrote:
| This object has quite the hyperbolic excess. There's no doubt
| it's not a solar system object.
| csours wrote:
| With Vera Rubin's Large Synoptic Survey Telescope coming online,
| we'll likely see many more of these. It seems like it would be
| very difficult to physically intercept any large percentage; what
| is the next best alternative to physical interception? Lasers?
| Masers? Comet trail sampling? Pre-staged
| interceptors?(Interstellar Interloper Interceptor? I'd be
| interested in entertaining the possibility)
| ahazred8ta wrote:
| "We are Engineers at the Vera Rubin Observatory, Ask Us
| Anything!"
| https://old.reddit.com/r/space/comments/1lwgfre/we_are_engin...
| Eduard wrote:
| https://archive.is/F3Vad
| layer8 wrote:
| The Wikipedia article [0] has a nice animation [1] of the
| trajectory through the inner solar system, sourced from this [2]
| 3D interactive viewer (press "Plot Object" and then drag the
| slider below "Change Time Speed").
|
| [0] https://en.wikipedia.org/wiki/3I/ATLAS
|
| [1]
| https://en.wikipedia.org/wiki/3I/ATLAS#/media/File%3A3I_ATLA...
|
| [2] https://neofixer.arizona.edu/css-orbit-view
| ddahlen wrote:
| I'm one of those astronomers! I'm working on my PhD in orbital
| dynamics.
|
| A lot of people are requesting discretionary time on telescopes
| trying to get observations in. The orbit will put us on the other
| side of the sun when 3I is nearest the sun in october, we can see
| it now and after it comes back out from behind the sun.
|
| Unfortunately, right now the it is in a very crowded star field
| (IE, its close to the galactic plane, lots of stars in the
| background).
|
| If you are interested in orbital dynamics, I have an open source
| rust/python package for accurate orbital calculations of
| asteroids/comets:
|
| https://github.com/dahlend/kete
| milleramp wrote:
| Is there a rule of thumb speed where an object is considered
| not from this solar system?
| bloak wrote:
| https://en.wikipedia.org/wiki/Escape_velocity#Calculation
|
| (assuming it hasn't interacted significantly with any other
| object in the solar system besides the sun)
| ddahlen wrote:
| Eccentricity!
|
| You can approximate the orbits of basically everything in the
| solar system using 2-body mechanics (IE, ignore the planets).
| If you do this you get orbits which are elliptical
| (eccentricity <1), parabolic (eccentricity = 1), or
| hyperbolic (eccentricity>1).
|
| If the object has an eccentricity above 1, its not bound to
| the solar system.
|
| Many long period comets have eccentricity hovering near 1,
| often these long period comets will be on their first pass
| (sometimes only pass) through the solar system. These comets
| though usually dont get much above eccentricity of 1. The 3
| interstellars we have spotted have had like 1.2 or bigger.
| This one is above eccentricity 6! Its moving fast.
|
| Edit: I have heard that when the first interstellar was found
| it actually broke a lot of peoples code, as it was common to
| hard code limits to allowed eccentricities (or simply not
| support ecc>1 at all).
| WD-42 wrote:
| This thing actually crashed our observatory software
| because we were trying to calculate position at too far of
| time horizons where because of the eccentricity the
| algorithms would not converge... that sucked but has been
| fixed. Ready for the next one!
| icehawk wrote:
| > often these long period comets will be on their first
| pass (sometimes only pass) through the solar system.
|
| Only pass because of the eccentricity, or for some other
| reason?
| ddahlen wrote:
| Oort cloud comets are so distant that they are only
| weakly gravitationally bound to the solar system. When
| they come in and we see them, they have enough energy to
| go back out to the extreme distances. Minor nudges from
| the big planets are enough to cause them to become
| ejected from the solar system (ecc>1). This can lead to
| the whole "one and done" thing.
| antognini wrote:
| How does Kete differ from REBOUND?
| (https://rebound.readthedocs.io/en/latest/)
| ddahlen wrote:
| Different goals, kete is meant to be aimed more toward
| observers and telescope data processing, all asteroids and
| comets at once on a laptop. Short term analysis (<100 years)
| and speed are the priority.
| metalman wrote:
| you lucky so and so
|
| many things are labeled historic, though some very very tiny
| number will actualy retain the power to inspire as this event
| will we have all dreamed of going into space to discover
| whatever is there, but as it turns out these interstelar
| objects are bringing us the only real physical evidence that we
| will ever get a good look at
| spenczar5 wrote:
| Cool to see! I spent a few years working on asteroid orbital
| dynamics too. What integrator are you using? Do you cover the
| weird stuff like Yarkovsky effects? That gets important for NEO
| impact risk, which is what I worked on.
|
| Matt Holman's ASSIST (https://github.com/matthewholman/assist)
| struck me as a breath of fresh air, coming from openorb and its
| kin.
| ddahlen wrote:
| I wrote a custom implementation of the Radau integrator, its
| been heavily modified. I have a lot of additional physics, it
| supports the non-gravitational models that JPL Horizons
| defaults to, so diurnal yarkovsky at least. I've been using
| it to study dust and small object dynamics, as they get
| pushed around by the sun a lot.
|
| It does an OK job for impactors, but the integrator is tuned
| heavily for performance, and the tolerance defaults are not
| great for impactors.
|
| I match jpl horizons for apophis to a few km, they have a lot
| more intense earth gravitational model then I care to
| implement, and by default I only include the 5 heaviest main
| belt asteroids, they have many more. That was the sweet spot
| for accuracy vs speed for me, overall accuracy goal is less
| than a few km over a decade.
|
| The goal is to be able to handle the huge influx of new
| asteroids that the catalog will have due to LSST and
| eventually NEO Surveyor (which I worked on for 3 years). Most
| systems I know have been throwing hardware at the problem, I
| tried to make fast and efficient enough software that we can
| use it on a laptop for 5-10 million asteroids.
| spenczar5 wrote:
| That is very impressive - getting the nongravs is a lot of
| work.
|
| Anything published on your integrator and its
| modifications?
|
| One nice feature of ASSIST (from what I remember, its been
| a while) was that I could add in more perturbers and crank
| up the gravitational harmonics if I wanted to. It sounds
| like you support that too at least for perturbers?
| ddahlen wrote:
| Final edits of a paper at the moment, aim to submit next
| week. Perturbers are easy to add, though a little poorly
| documented at the moment. Additional physics right now
| are J2 of jupiter/sun/earth, and GR corrections for the
| sun and jupiter.
|
| Biggest speed gain is that I have a custom SPICE reader
| that is multi-core friendly (I re-implemented a lot of
| the SPICE standard in rust), and it is used as the source
| for planet positions. Being able to skip planet
| integration leads to massive speedups.
| xoxxala wrote:
| Sixty Symbols has a nice overview video on 3I/ATLAS:
|
| https://www.youtube.com/watch?v=VRHZUH0RcQ4
| skc wrote:
| My mind is boggled at the speed with which an object that size is
| travelling.
|
| Amazing.
| GMoromisato wrote:
| The designation 3I means the third interstellar object
| discovered. 1I (Oumuamua) was discovered in 2017, and the new
| Vera Rubin telescope is likely to discover a lot more in the
| future.
|
| We're just at the beginning of finding this new population of
| objects, and I think it's very exciting. It's like when Ceres was
| first discovered (in 1801) and suddenly people found a whole
| population of asteroids between Mars and Jupiter. We're in a
| similar time now with interstellar objects.
|
| How many interstellar objects pass through the Solar System each
| year? How many will we find in the next 10 years? We're about to
| find out.
| rbanffy wrote:
| I often wonder what would it take to have a rocket capable of
| launching a pre-packaged probe to intercept such objects. What
| would it look like? An SLS with a cubesat on top?
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