Except, that dichotomy is a simplified fiction. The reality is that there are objects in the middle, sometimes called "iceteroids" which we've discovered over the years. These could be the cores of comets which have lost most of their ices or these could be objects with more complicated histories, such as asteroids which have accreted surface layers of ices through various processes.
So this is a mystery but it's not some enormous mystery it's a small mystery. The idea that an asteroid could have acquired a small amount of ices on its surface isn't exactly world shattering news but because we don't know the history of the object we don't know the process by which it ended up with its observed properties.
Here in the Sol system, we have a pretty strange arrangement of planets , with big ones all in the outer system and smaller ones in the inner system. So looking at just our system is not very indicative of 'typical' system evolution, in terms of iceteroids. Once we figure out where Oumuamua came from, that'll give us some idea of the compositions and evolutions of other systems (data point of 1 is better than 0), like the frost line. Oumuamua should be viewed as awesome and exciting, but as the tip of the ... iceberg ... when it comes to the real questions of stellar evolution and all the awesome stuff happening there.
The obvious followup here is that we need way, way more closeup observations of small bodies in our own Solar System, we probably also need to develop better techniques for observing interstellar interlopers, and we need to improve our studies of extrasolar planetary systems. Fortunately the first part is already covered, between the Hayabusa 2, Osiris-REX, Lucy, Psyche, and New Horizons missions we should collect a lot more information on such bodies. However, it's probably going to be a long time before we have answers even to simple questions like the formation histories of most small bodies in stellar systems and what the "average" stellar system looks like.
Hopefully (knock on wood) JWST gets up there soon and a LOT more questions can be answered.
One issue we have is that there is this 'gap' in planet formation modeling. We can figure out small bodies and large bodies, but things that are ~1m to ~1km in size don't work in the models; they should all just fly apart. Somehow planets do form, but getting there is a pickle, theoretically. Asteroids are likely THE key to understanding that gap, and that should help out with a LOT of system formation dynamics.
Also, I'm still bullish on finding a LOT of platinum/gold on asteroids, because space mining. Like, eat your heart out Bruce Willis.
I also wish more media ran articles like this. It's fun to let your imagination run wild, apply a bit of math and visualization, and also learn lots in the process. And there's no division. Even if somebody says something completely wrong, people can have fun correcting and adjusting their views like a collaborative project instead of some competition to 'prove' your subjective interpretation right, as so many other topics devolve into.
I mean, we just discovered ten new moons of Jupiter this year: http://earthsky.org/space/10-new-moons-discovered-jupiter-1-...
Just imagine how tragic it would be, if an ancient artifact of an alien civilization drifts by earth and we don't manage to have at least a look at it.
I hope one day we'll get a solar system wide observation network. Like the current arrays of radio dish observatories, but on a solar system scale.
'Oumuamua is red and headed toward Pegasus (the winged horse) after a very long journey starting longtime in spacetime ago. It is wildly tumbling off-kilter and potentially creating a magnetic field that would be useful for interplanetary spacetravel.
They're probably pointing us to somewhere else from somewhere else.
If this is any indication of the state of another civilization's advanced physics, and it missed us by a wide margin, they're probably laughing at our energy and water markets; and indicating that we should be focused on asteroid impact avoidance (and then we will really laugh about rockets and red electromagnetic kinetic energy machines and asteroid mining).
[We watch it fly by, heads all turning]
Maybe it would've been better to have put alone starman in the passenger seat or two starpeoples total?
Given the skull shape of October 2015 TB145  (due to return in November 2018),
maybe 'Oumuamua  is a pathology of Mars and an acknowledgement of our spacefaring intentions? Red, subsurface water, disrupted magnetic field.
In regards to a red, unshielded, earth vehicle floating in solar orbit with a suited anthropomorphic creature whose head is too big for the windshield:
"What happened here?"
Of course reaching it and landing on it, especially at these speeds, are two completely different things.
1: [’Oumuamua] was being slightly accelerated by an unseen force, which they argued could only be attributed to comet “outgassing” acting like a thruster.
2: Now in a new study that is currently under peer review, Roman Rafikov, an astrophysicist at the University of Cambridge, argues that the same forces that appeared to have accelerated ’Oumuamua — the same forces that should have also produced a tail — would have also affected its spin. In particular, the acceleration would have torqued ’Oumuamua to such a degree that it would have spun apart, breaking up into smaller pieces. If ’Oumuamua were a comet, he argues, it would not have survived.
For all anyone knows the intrinsic brightness was variable.
(This is probably not very likely without some supporting spectroscopic anomalies. But still.)
As for thrusters - that's the same problem as the comet and outgassing hypothesis. No known mechanism can explain the acceleration.
And if you were alien race and wanted to look at a planetary system without attracting attention, something that looks like a tumbling rock with a plausibly improbable trajectory would be ideal.
It could just be a coincidence that the first large proven extra-solar object slingshotted around the Sun in a way that happened to pass close by the Earth.
But considering the size of the Solar System and the convenient phasing of the Earth's orbit, what are the odds? It's certainly very curious.
Someone just f'ed up the config files?
Sorry couldn't resist and hey, it's also Friday today.
I wonder if it was aliens and they made it just slightly interesting without making it look completely obvious. Then they'd monitor and see how we would react. Would we be able to detect. Would we go chase it? Beam microwaves at it. Do we have the capability to fire projectiles at it.
To make its being engineered seem implausible, surely.
As for the unexpected attraction, as one of the moon astronauts displayed, objects of different mass are attracted (fall) equally quickly by gravity in a vacuum.
Easy enough to test -- we'll eventually see another object following the same trajectory, give or take, but that's decelerating.
(Cue the dramatic music.)
One favourite daydream of mine is to think about how the Rama aliens' second and third probes would be received. I read Rama around the same time as Eon by Greg Bear, so I've always had an affinity for spin-gravity habitats filled with unknown stuff :)
With The Expanse TV series showing us how good hard scifi can be exciting and wonderful, I'm hoping we one day get an Eon or Rama series. Rama especially would work well in a hard scifi miniseries format.
(That's actually a great thought: that many shows thought impossible a couple of decades ago will now be made. Let's just hope they're made with love and devotion like The Expanse!)
That's the only way to explain how awful some of his last books were.
Having said that, I liked Richter 10. Too bad the co-author died before they could write another one.
It's fun to speculate, but I'm sure the reality of the situation is far more boring.
The thought makes me have goose-bumps. Did some alient race just take a close look at us? Was there a voyager-style plaque on it? I guess we'll never know now.
Occam tells us that in reality it is most likely just some space debris from some ancient rock-smashing incident, but the fact that this thing continues to defy classification allows us some space to imagine!
1 - https://duckduckgo.com/?q=voyager+gravity+slingshot+diagram&...
Look at it from a sampling bias perspective. The object at its brightest was very dim (19th magnitude) and moving fast. The ability for rapid, repeating full sky surveys is recent (PanSTARRS had been online for around a decade). The limiting magnitude of PanSTARRS is 24th. So if such other such objects exist, of course we are going to find the closest ones first since they are the brightest.
That is incorrect. All motion is not relative, only intertial motion is relative. Spinning implies acceleration on a body which is measurably different from any reference frame compared to a body that is not accelerating
Imagine you're off somewhere space. You're holding a ball in each hand.
1. You're motionless with reference to the Earth. You let go of the balls. They stay put.
2. You're moving away from the earth with a constant velocity. You let go of the balls. They continue to move at the same velocity as you do: This is indistinguishable from case 1.
3. You're accelerating away from the Earth (using rocket boots). You let go of the balls. They do not continue to accelerate with you.
4. You're motionless with respect to Earth, except that you're spinning. Think of the fastest you've ever spun. You'll be really dizzy when you stop. You let go of the balls. They fly off into space, because in order to stay spinning, they need acceleration toward the center of the spin plane. By letting them go, you stop that acceleration, and their trajectory changes (or really, their trajectory change stops).
Velocity is all relative, but acceleration is not. Spinning is acceleration.
Here's another example:
You occupy a cosmos consisting only of you and an apple. You accelerate away from the apple for a moment, then stop accelerating. You now have a constant velocity away from the apple, but it's meaningless to say which of you is actually moving. You each perceive the other as moving away at constant velocity.
Now imagine you start spinning. You feel like you're spinning, and visually, you perceive the apple orbiting you at a bizarrely fast rate. From the apple's perspective, you are spinning. These two perceptions are not symmetric.
Is the point here that I’m spinning with reference to my direction of motion?
This is how plausible simulated gravity works too. A ship spins. It doesn’t require a reference to know whether it’s spinning.
Dirk Schulze had taken that as a subject into his sci-fiction book - Alien Encounter.
Now for a space ship, I agree. Though even then you might benefit from that extra matter in the same way.
Asteroid are per definition not interstellar though (until Oumuamua?).
I'd love to see a scenario where we'd build robot terraforming fleets that'd land on an uninhabited planet, make it habitable, complete with spaceports, cities, factories, crops (all permanently tended for robots), build a couple extra fleets and launch to their next most promising targets.
And then, for some reason, humans lose interest in all that and someone else wakes up to find a universe full of 60's futuristic utopian planets nobody ever lived in.
Reminds me of the paperclips game . Would be horrid to find those people wake up and find the universe transformed into nothing but paperclips. 
A tumbling probe that doubles as a cosmic pointer to home. Cool.
Maybe somebody should check if that "slightly acceleration" bring it closer or farther to Earth.
Maybe we have been photographed. I hope it's not that somebody shoot us and failed.
100%, because it happened