
The first known object to enter our solar system from deep space - thrusong
http://www.cbc.ca/news/technology/astronomers-interstellar-visitor-1.4410477
======
Cal___
I think it's a shame that this story hasn't gotten more attention.

True, it doesn't tell us as much about the nature of the universe as the
discovery of the Higgs boson, and it doesn't represent a major advance in
engineering like gravitational wave detection. But it is the only chance we
have ever had to directly view a largeish piece of another solar system, just
millions of miles away. The next time probably won't come until we send a
probe to Proxima Centauri.

To me, the thought of an asteroid being hurled out of the solar system that
created it, then traveling through the cold void for millions or possibly
billions of years, and then whipping around the sun (a mere 0.25 AU distant)
is just the most incredible thing. The whole world should be having parties in
its honor, to wish it well as it leaves us behind. (Instead of just fighting
each other over nothing, as we usually do.)

This is an amazing time to be alive.

~~~
nkurz
_But it is the only chance we have ever had to directly view a largeish piece
of another solar system, just millions of miles away. The next time probably
won 't come until we send a probe to Proxima Centauri._

While this is the only one we've seen so far, the current belief is that
similar objects might actually quite common. A parallel newspaper article in
the Guardian [1] cites a paper out of UCLA [2], and works through the math:

    
    
      The other group of astronomers, led by David Jewitt,
      University of California Los Angeles, estimated how 
      many other interstellar visitors like it there might
      be in our solar system.
    
      Surprisingly, they calculate that another 10,000 could
      be closer to the Sun than the eighth planet, Neptune,
      which lies 30 times further from the Sun than the Earth.
      Yet these are currently undetected.
    
      Each of these interstellar interlopers would be just
      passing through. They are travelling too fast to be
      captured by the gravity of the Sun. Yet it still takes
      them about a decade to cross our solar system and
      disappear back into interstellar space.
    
      If this estimate is correct, then roughly 1,000 enter
      and another 1,000 leave every year – which means that
      roughly three arrive and three leave every day.
    

So now that we now to look for them, it may be possible that we'll be able to
find others, at least before the probe reports back from Proxima Centauri.

[1] [https://www.theguardian.com/science/across-the-
universe/2017...](https://www.theguardian.com/science/across-the-
universe/2017/nov/20/interstellar-object-confirmed-to-be-from-another-solar-
system)

[2]
[http://www2.ess.ucla.edu/~jewitt/papers/2017/JLR17.pdf](http://www2.ess.ucla.edu/~jewitt/papers/2017/JLR17.pdf)

~~~
pqh
Would it still be travelling too fast to be captured if it hit the sun
directly?

~~~
macintux
Is something technically captured by a gravity well if it just happens to hit
the object at the center? I assume not.

~~~
isoprophlex
At the very least, I'd say that... after collision, assuming complete
coalescence into the object, they will share identical orbital parameters

------
Tossrock
I recommend anyone interested read the paper which is available as a preprint
from Nature (for the moment): goo.gl/cSsHoj (link shortened due to having an
embedded access token).

Some tantalizing points from the paper:

\- They constrained the aspect ratio in two dimensions to be 10:1:C, but the
third dimension is unconstrained. Depending on which axis the object is
rotating around, C could either be 1, or 20. Either of these would be an
essentially unique object within the solar system. This is a really weird
shape.

\- If the object is rotating around its short axis, it must have internal
tensile strength (ie, it's a solid object, not just a pile of dust/gravel
accreted by gravity). Lower bound on the required tensile strength is 3 Pascal
(very little).

\- There is essentially no dust/ice on the object - less than 1 kg within
2.5". So it's not a comet, and would have to be asteroidal. This conflicts
with our current understanding of what objects would be in interstellar space.
Current models have almost all objects ejected from our system being icy
comets. This object would be analogous to a Manx comet, ie a rocky asteroid in
a highly elliptical long period orbit.

\- The shape of the observed light curve deviates from the best-fit triaxial
ellipsoid in a way that suggests large flat or concave sections. It would take
unrealistically large albedo variations to produce the same deviation without
flat/concave sections.

And of course, of all the planets in the solar system, it made its closest
approach to Earth, an astronomical "near miss" at just 0.16 AU :)

~~~
tehwalrus
\- strange aspect ratio

\- tensile strength (it should be cartwheeling, there is a physics theorem
which means everything tends to this configuration)

\- large flat or concave sections.

\- others are reporting it's mostly metallic.

I'll say it: did anyone consider an alien spaceship? The paper seems to deduce
"asteroidal" by ruling out other things, rather than by a positive measurement
of rock spectra, unless I've misread it.

~~~
ldenneau
Co-author here. We obtained spectroscopic measurements of 'Oumuamua, and its
surface closely matches D-type asteroids and comet nuclei, which are dark,
reddish and organic-rich.

~~~
pbhjpbhj
Of course an asteroid, hollowed out somewhat, makes for a good spaceship.
Especially if you're trying to be covert.

Perhaps someone has discovered warp drives (is gravitational wave detection
the first step) and the Federation have sent a ship to observe us.

~~~
wallace_f
If you wanted to disguise a probe, it seems the ideal form would be a black
body, not to disguise it as an asteroid, I would guess. Unless they're playing
mind games.

Anyways, given all the EM radiation we're tossing out into the void, some
species' probe out there is going to pick up our existence sooner or later.

And at ~395 earth-moon distances it's difficult to imagine how effective a
400-meter object, disguised as an asteroid, would be at seeing much detail on
earth.

But it is tantalizing and fun to imagine--the appearance of a gravity boost...
Flat surfaces... Near to earth... Lack of any ice or outgasing, a solid
object, many characteristics not seen in other known-asteroids, rotating on
its long axis... :)

~~~
ceejayoz
> And at ~395 earth-moon distances it's difficult to imagine how effective a
> 400-meter object, disguised as an asteroid, would be at seeing much detail
> on earth.

Ah, but it's a carrier for the small, stealthy probes!

~~~
sandworm101
And waterbears.

------
madlag
What a pity they did not call it Rama ;-)

[https://en.wikipedia.org/wiki/Rendezvous_with_Rama](https://en.wikipedia.org/wiki/Rendezvous_with_Rama)

~~~
Grangar
Would be interesting if it changed course.

~~~
Jyaif
"interesting" is an understatement. We'd instantly have a new space/weapon
race.

~~~
Unbeliever69
The premise of Saturn Run

------
nichtich
If there're a lot of these objects entering and leaving solar system every
year, and suppose some day in the near future we can keep track of them all,
can we use them for us to send out larger probes? We see a rock coming near
us, and send out a probe to its path. And before the collision the probe
create a buffer object at the rear end so that it wouldn't be totally
destroyed. After that the probe can free ride for a while at a high speed and
re-ignite when it decides to go a separate path.

~~~
Cyphase
Not sure about a buffer object, but a tether on a reel might work.

You harpoon the object, then let it pull the probe, giving lots of slack
according to the engineering tolerances of the harpoon in the object (don't
want it to come loose), the tether (don't want it to snap), the reel (don't
want it to spin apart or get stuck or any one of a number of things), and the
probe (don't want it damaged under extreme acceleration).

With enough tether and a low-enough-friction reel with magnetic bearings
(think of the ungodly RPMs), you can accelerate the probe at almost any speed
you'd like, within reason, although it would be best to accelerate as quickly
as possible without risking. And remember that you only need to get the whole
harpoon/tether/reel (HTR, or HiTchhikeR; you saw it here first) mechanism in
range of the object as it passes by, so it can be bulkier than you would put
on a probe moving under its own power. Or you could start off as usual, maybe
with a gravity assist, which would allow for a less sophisticated HTR.

Then if you want to be clever, you can turn all those RPMs into stored energy.
But that might not be worth the trouble.

~~~
wallace_f
Might be possible, but the tensile strength required may be beyond our
material science capabilities.

A harpoon impacting an object going 26km/s would experience something like
12,000gs even if you gave it a 1km-long buffer.

So your harpoon would have to be rocket-assisted. The problem now is how long
does your need to be? The tensile strength to carry the weight of the tether
itself may make this impossible.

~~~
Cyphase
> Might be possible, but ... may be beyond our material science capabilities.

Certainly, for now and a while to come.

~~~
wallace_f
Perhaps some ultra-lightweight probe using some sophisticated ultra-strong
elastic tethers may be a way to accelerate an object at an orders of magnitude
greater speed using asteroids as counter-weights. Probably nothing strong-
enough, though.

------
PokemonNoGo
Very interesting! So all known "stuff floating around in our solarsystem" like
Hale-Bopp et al have been deemed originating from here? Or have that
conclusion just been taken for granted?

Edit:

Looked at the paper and saw this in the 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.

Very interesting that this has been the thought of affairs for objects in our
solar system. I have never contemplated it and just assumed we must have been
visited before by such objects.

~~~
marcosscriven
It’s apparently to do with the orbit - they identified this as extrasolar
purely by the fact its orbit would be extremely unlikely to have arisen from
our solar system’s protoplanetary disk.

------
Santosh83
Found to be among the most elongated deep space objects known:
[http://www.bbc.com/news/science-
environment-42053634](http://www.bbc.com/news/science-environment-42053634)

Can't help but think of the Chindi!

------
stmfreak
Elongated is not a very natural shape for rocks in space. It is going to get
real interesting if this thing starts slowing down.

~~~
kobeya
Already passed the Sun.

~~~
avian
Which means it is in fact slowing down as it climbs out of the Sun's gravity
well. It's just not the kind of slowing down that parent was hoping for.

------
rodolphoarruda
I thought "deep space" was intergalactic space, the really big void. But if
the object came from within the Milky Way itself, it came from a rather busy
place -- speaking in Universe terms.

------
z3t4
How close to earth did it pass ? A possible extinction event just flew bye and
there where nothing we could do about. Btw, that looks like a gravity
assist/slingshot ...

~~~
Tossrock
0.16 AU, according to the paper.

~~~
semi-extrinsic
For comparison, the Earth's radius is 0.00004 AU. This is like a mosquito
passing your car at a closest distance of 2 miles.

~~~
wallace_f
~395 earth-moon distances away and 1/20th the size of the object that killed
the dinosaurs

~~~
Jyaif
1/20th the size, but 4 time the speed. Assuming the density of the 2 objects
were the same, and because energy is proportional to the square of speed, it
would cary a similar amount of energy.

------
vortico
What was its speed at closest sun approach? Because the speed of objects in
our solar system are all very low compared to the speed of the nearest solar
system compared to our sun, I imagine this could also be the fastest object
ever to be obversed in our solar system.

~~~
Tepix
Its speed peaked at 87.71 km/s at perihelion.

~~~
planteen
It looks like there was a sungrazer comet an order of magnitude faster than
that at 600 km/s (2.16e6/3600), so this was not the fastest solar system
object ever.

[https://futurism.com/the-sun-just-killed-the-fastest-
moving-...](https://futurism.com/the-sun-just-killed-the-fastest-moving-
object-in-the-solar-system/)

------
AKifer
Forget about going to Mars, making a probe riding these things will be much
more interesting.

~~~
flukus
I just recently read (well, listened to) Pushing Ice
([https://en.wikipedia.org/wiki/Pushing_Ice](https://en.wikipedia.org/wiki/Pushing_Ice))
which is along these lines. Fantastic story for anyone that likes hard sci fi,
it starts off with a moon of saturn suddenly breaking out of orbit and the
crew being sent on an intercept mission.

------
Mikho
The first thought looking at the picture -- it could be interstellar probe
created by some alien race. Rotation and metal body -- something to think
about. This reminds me "The Dark Forest Theory" described in the fantastic
trilogy "The Three-Body Problem" by Cixin Liu [1] -- Chinese Isaac Asimov.
Really great read in case you didn't read it yet.

[1] [https://www.amazon.com/Three-Body-Problem-Cixin-
Liu/dp/07653...](https://www.amazon.com/Three-Body-Problem-Cixin-
Liu/dp/0765382032/)

------
sanatgersappa
is it looking for whales?

------
lawlessone
Could we ever use a net to stick a probe to one and get a free trip out of the
solar system?

~~~
colemannugent
I think that because it is moving so fast the net would have to be accelerated
significantly so that it wouldn't just tear through the net.

Plus there's the issue of actually getting into position in time to setup all
the maneuvers required to match the speed.

------
woodandsteel
It was a test. If we had blown it out of the sky, then the aliens would know
we are armed and dangerous, and they better stay away.

But we didn't do that, and that means, well, let's just say things are going
to get rather interesting.

------
erikb
I don't get the excitement. I thought it's common that stones of different
sizes enter our solar system take a loop and exit again. That's exactly what
this tourist plans on doing, or not? What's different?

~~~
Santosh83
Yes but this is the first _observed_ instance of a stone that seems to come
from outside the solar system and outside the Oort Cloud even, so basically
from interstellar space. And its shape and albedo or unusual too, seemingly.

------
entitywang
If all those sci-fi movies have thought me anything, that's a spacecraft
masquerading as a rock. You can't fool all of us aliens!!!

------
mrfusion
Did anyone check if it is rotating and at the right rpm to produce planetary
gravity inside?

------
i_feel_great
It could very well be vampires[0]. So please leave it alone.

[0][https://en.wikipedia.org/wiki/The_Space_Vampires](https://en.wikipedia.org/wiki/The_Space_Vampires)

------
ForFreedom
Now, what if it turns out to be an alien ship?

------
gdubs
Wish Carl Sagan were still alive.

------
jasonmaydie
i'm surprised there aren't more things entering our solar system from deep
space considering how large the universe is

------
org3432
Famous last words?

------
known
I don't think we earthlings are constantly watching every corner of our solar
system.

------
_Codemonkeyism
"This artist's concept shows [...]"

F __you artists concept. Drawing fantasy pictures in news messages is not ok.

\+ I'm no grammar guy, nor a native speaker, but "artists's" is wrong, isn't
it?

~~~
nothrabannosir
Artist’s is fine (“artist his”), artists’s would be artists’. Depends on how
many people worked on the art piece :)

~~~
pgalu
For the record, the expansion "... his" is considered "folk etymology": a
reanalysis from the Early Modern English period in the language's history.
Notice for example how it doesn't make sense for feminine words: "Mary's
house".

In fact, the possessive "'s" is a leftover from Old English, where the
inflectional suffix "es" marked the genitive case.

~~~
nothrabannosir
Yeah it's a mnemonic device, nonetheless quite useful to explain the rule.

