We didn't find it until 40 days after perihelion? It had already passed Earth's orbit and was quite a bit of the way out to Mars's orbital. Ugh. Can we never let this happen again? Solar wind density is directly proportional to 1/r² (r=distance from the sun), but the speed is not a function of distance. Both are subject to significant variations related to processes on the sun's surface and in the solar corona. So you could absolutely model future anomalous acceleration in addition to what we've seen already, but the question is always how well we can resolve it, as the density will continue to drop off pretty quickly, and thus the magnitude of any pushing grows less. Maybe we have some earth-orbiting black ops imaging tech pointed up instead of down that can help us out? Edit: There is one possible alternative explanation, but it doesn't make much sense: 'Oumuamua could be strongly magnetized, and would interact with the solar wind's magnetic field. But I dunno, if you look at 'Oumuamua's trajectory: you'll see that the path we've gathered data for is only ~20 degrees outside of the ecliptic plane, so the solar wind magnetic field orientation might still be somewhat chaotic (reference, I will explain if prompted), which doesn't favor imparting a net force, i.e. some anomalous acceleration. But wait! This entire paragraph's worth of speculation is totally invalidated by the fact that Oumuamua is tumbling, a chaotic motion (see the intermediate axis theorem), which is guaranteed to lead to no net accrued time of some embedded magnetic field oriented in a particular direction. Still edit: It could be possible that the object is engineered to cleverly extract energy out of electromagnetic fields like those present in a star's "solar wind". We should send something after it. The project might take 30 years for launch and rendezvous, and then several months to send back data, but it can be done. We should look and see if we can catch it pinging somewhere else. Maybe bring a compact neutrino sensor (LOL, physics joke), 'cuz if I were an advanced species, I'd encode messages in neutrinos. It'd prevent filthy casual civilizations from detecting my interplanetary sexts (encoding information electromagnetically was so pre-post-re-evolution, circa only 2 Gyears post-Big Bang for my world, ya know?).
I don't think it is, but f it is first contact. we're just sitting here watching and pointing at it as it's flying past pointing and going "ooooooh".... Here's hoping we're better prepared for second contact. We're constantly discovering new things we can't explain or understand about space, the universe in general, even our own solar system. To me it feels like true hubris to assume it's evidence of anything other than our lack of knowledge about the universe and how it works. We've just discovered something else we can't explain. WHoop de doo - add it to the list. We didn't find it until 40 days after perihelion? It had already passed Earth's orbit and was quite a bit of the way out to Mars's orbital. Ugh. Can we never let this happen again?
It's maddening that no one in the space exploration community is openly talking about this. Here, I can do it pseudonymously :D. Edit: of course, the majority skeptic of me doubts that it's ET tech, but how much of a disappointment would it really be to send something after it that only did science on a piece of rock from another solar system. Major achievement unlocked.
According to this article, the strongly magnetized object hypothesis is unlikely to be the only source of anomalous acceleration. To quote: (Changed some of the typography to make it more readable.) I'm somewhat interested in the odds of an interstellar object not having a neutral magnetic field. Intuitively, lack of net charge or magnetization should be the norm but I'm far out of my depth here. Also: consider yourself prompted.If ‘Oumuamua had a strong magnetic field, then interaction with solar wind could affect its motion. Assuming a dipole field, a plasma-fluid model and typical solar wind speed and proton number density, we find the resulting acceleration for an object of the nominal size of ‘Oumuamua to be only 2 × 10^(-11) m/s², too small by a factor of about 10^5, even if we adopt the high magnetization and density of asteroid (9969) Braille.
What if we chose a dipole moment for 'Oumuamua consistent with a superconducting medium, just to be conservative? That'd take some physics in and of itself just to get a best guess and some error bars. Like I said though, it still might not matter, because if we're seeing a quasi-chaotic rotation, there's no preferred orientation over an 8-ish hour period. But I guess it's possible that for big events (like coronal mass ejections), the shock front arrival in the solar wind could do some pretty big pushing or pulling via magnetic coupling. I would wanna see the 'Oumuamua position/acceleration data, and then I would look at the solar wind data and make some cheap little analytical model of expected forces. I'd keep Oumuamua's rotation phase angle as a free parameter. The solar wind data source I usually use is FURLOUGHED, by the way :(. Right, so, about the thing you actually prompted me about. The superimposed blue and red squiggles circumscribing the solar disk are the interplanetary magnetic field (IMF) orientation, which is very clearly a function of solar cycle. In the first panel, six years of data from Ulysses (a polar orbiting sun-observing satellite) is shown. The first six years were generally near solar minimum, unlike the second panel, whereas during the second 6 year orbit, the sun was generally near solar maximum. So if 'Oumuamua was ~20 degrees off of the solar equatorial plane (which is itself only +/-5 degrees from the ecliptic plane), it could maybe see a heavily-preferred magnetic field. People model this stuff hardcore, btw, and my bad if I've linked that before. But maybe big events could more clearly influence 'Oumuamua, either from a huge moment via comically large superconductivity, or a thin disk interacting with the solar wind ram pressure, or both. Again, depends on observational fidelity. Edit: regarding the Ulysses data, I just read the written paragraph on the site and I didn't give much more than was already there, so specific questions are welcome. As an example, if Mars were to have something hit it, and a chunk was to break off, it would be a magnetized chunk, albeit extremely weak compared to a superconducting moment (duh, srry, pedantry). The Martian mantle cooled below the Curie temperature like a billion years ago and the local orientation of the global magnetic field was frozen in. I dunno about asteroids, that study makes it sound like they can have pretty big magnetic moments. Comets are probably never magnetized whatsoever, or at least the one we've visited had no measurable moment. Maybe we should consider the possibility that it's neutral. So just consider everything, good advice, am_Unition, thx!
Maybe! Same story on the experimental side. It depends on our ability to precisely measure a difference in the brightness profile vs. our ability to precisely measure position. And fit either to decent models. Yeah, most probably. That's a really weird range of parameter space to characterize though. Like what if two of Jupiter's moons eventually slammed together, you could actually end up strongly magnetizing a piece of ejecta if it was cooled below the Curie temperature somewhere near its perijove, if it had juuuuuust the right initial conditions. I hadn't really thought about that before, but now I'm convinced that the magnetic properties of meteors are typically 99%+ compromised by the time they make meteorite status because of the intense heating during atmospheric entry. But dude, that potentially means that the magnetic flux from meteors with large magnetic moments is somehow put into energizing the plasma sheath surrounding the thing during its "shooting star" phase. The worst part is that I don't think anyone will pay you to study such a phenomenon. :(I guess it would magnify the effect but make a measurable change to the tumbling motion?
Wouldn't ejecta from such impact become at least largely demagnetised by a combination of shock and temperature?
I'm not sure (and can't seem to find conclusive papers/sources) if what we measured on Earth is mostly the original, unchanged field.
1) From an astronomical standpoint, it ain't a big thing. We're talkin' about an object around the rough size of a football stadium. 2) If I had something shaped like a giant cigar and I were trying to not get noticed, I'll bet my AI would go "quick, act like an asteroid" as soon as I had a reasonable read on my observed race's intelligence. "Tumbling" is such a nasty word. It's got a periodicity of 8 hours. Sucker's "tumbling" about 1/10th as fast as your average revolving restaurant. 3) We should totally send something after it. That's the sort of speedboat space exploration your average Red Stater can get behind.
My mom goes, "The size of a city block?! And we almost didn't SEE IT???". Yeah, that's microscopically small to astronomers, and it was never closer than 100 million kilometers. And hey, remember that passive listening device scheme re: U.S. diplomats in Cuba and that seal thing we got from Russia (which still still cracks me up, btw)? What if this was the astronomical equivalent, and instead of a microwave source, it did something clever with the blackbody radiation spectra that we know all stars produce? Maybe it'd have to target only main sequence stars or something. Why not tumble the whole time? It'd be a clever way to ensure that every point in 'Oumuamua's visual field faces some preferred plane of R̶a̶m̶a̶ 'Oumuamua (you are getting very sleepy). But 8 hours on astronomical timescales gets the same reaction from astronomers as the football stadium size. Tumbling refers to the type of motion, though, not the rate. Maybe it would have to stop tumbling to effectively phone home though, that's an interesting thought. Sucks 'cuz the plane in which 'Oumuamua's hyperbolic path lies is far enough from the ecliptic plane (~20 degrees) that gravity assists aren't so much on the table. So it's way harder to find a trajectory that gets us there quickly, if one exists at all. Falcon Heavy with the lightest spacecraft possible, please. So we're already in the several hundred million$ price range. Woof :(1) From an astronomical standpoint, it ain't a big thing. We're talkin' about an object around the rough size of a football stadium.
2) If I had something shaped like a giant cigar and I were trying to not get noticed, I'll bet my AI would go "quick, act like an asteroid" as soon as I had a reasonable read on my observed race's intelligence. "Tumbling" is such a nasty word. It's got a periodicity of 8 hours. Sucker's "tumbling" about 1/10th as fast as your average revolving restaurant.
3) We should totally send something after it. That's the sort of speedboat space exploration your average Red Stater can get behind.