
Could 'Oumuamua be an icy fractal aggregate ejected from a protoplanetary disk? - Santosh83
https://www.syfy.com/syfywire/no-oumuamua-is-not-an-alien-spaceship-it-might-be-even-weirder
======
gus_massa
At least this makes sense. Perhaps calling it a fractal is an unnecessary
spin, but if it is linbaity enough to cover the spaceship theory I'm in.

More than a fractal, it is better to imagine it as a pile of recently fallen
snow is a day with the correct climate (cold?), so the snow accumulates but it
doesn't compact too much. So the density is much smaller than the density of
ice that has been in a glaciar for years under a lot of pressure. Since the
gravity is too low, it will no compact too much.

The main difference is that it's not a pile of real snowflakes, ut a pile of
dust "snowflakes". Otherwise, the ice in the real snowflakes would have been
partially evaporated by the sun and it will be classified as a comet.

Anyway, it would be interesting to read more technical details about the
plausibility of this. Can the dust pile survive the micrometeorites? Does the
color profile match a dust pile object. I really don't like the starship
hypothesis paper, but at least it contains a good analysis of many of the
(secondary) objections.

~~~
sandworm101
And can that loose pile of dust survive even a slight rotation. If it is long
and thin, the dust near the tips should separate.

~~~
gmueckl
There are mechanisms by which tiny particles may bond over time without
becoming more dense. The only prerequisite is that individual atoms or
molecules can move on the surface of the particles. This is true for a wide
range of conditions, but usually is extremely slow.

------
komali2
> It seems far more likely that objects like 'Oumuamua are relatively rare,
> and that means it likely came from someplace close by (if it came from
> farther away, the odds are even lower we'd ever see one).

Ok, it's on my list of things to do this year to actually learn how statistics
work, but my naive reaction to this supposition, which I read is "the fact
that we have encountered Oumuamua means that it's likely it didn't come from
far away, because if it did, it's less likely we would have encountered it,"
is: We _did_ encounter it. Just this one, ever. How can we draw any
statistical information from that? Either we encountered it, or didn't, how
does that have any bearing on the statistical probability of seeing it?

~~~
azeirah
I don't know much about statistics, but I can add that the time period
matters. If we only started observing space yesterday, and saw it, it would be
weird to say "it's rare", but we've been observing space for, I don't know, up
to 400 years? (counting since invention of telescope, 1608)

~~~
nkrisc
I don't think an object like this could have been spotted until relatively
recently.

------
crispyambulance
No one can say for certain what Oumuamua actually is-- other than it is "a
surprise".

What it really is, IMHO, is a call to action for better instrumentation so
that the next time one of these things pays us "a visit", we're in a position
to find out more about it.

~~~
ianai
AFAIK we don’t have many satellites around the other planets. I think we need
many more. Each planet could have at least one telescope, comms satellite, etc

~~~
planteen
Mars and Jupiter have orbiters and Saturn had one until recently (Cassini).
But what good do those do? They are planetary science missions, largely
useless for observing very distant objects.

I think what you are proposing is having a bunch of large space telescopes
around planets. But this might not help very much. All the planets are in the
plane of the ecliptic. Interstellar objects are not going to be aligned with
the plane of the ecliptic.

~~~
ianai
For stuff like this. For stuff we can’t even fathom yet. The world didn’t need
the amazing diversity of organisms that it has, but then we can’t imagine a
world without it. The “swarm” offers a lot more than just numbers, but it also
offers numbers. Arguing against each planet having observatory abilities and
comms is not that far from dismissing all progress on the basis that “well
were already pretty well off.”

~~~
planteen
You have to weigh it against the very finite budget of space programs. NASA
does this as their decadal surveys. There is no shortage of ideas and serious
concepts.

The difficulty of putting Hubble or JWST sized telescopes in orbit of other
plants is immense. They need constant maintenance as well and will take years
to reach their intended targets.

B612/Sentinel has been "in the works" for at least 8 years, but still doesn't
have consistent funding. This would be in a Venutian orbit to looks for near
Earth objects.
[https://en.wikipedia.org/wiki/Sentinel_Space_Telescope](https://en.wikipedia.org/wiki/Sentinel_Space_Telescope)

IMHO, a more useful location for a space telescope rather than in orbit around
another planet would be phased 6 months off of Earth at 1 AU. This would let
us continuously observe the "sun side" of space.

~~~
ianai
I don’t see this as a this or that calculation. I see this as a civilization-
level infrastructure project /imperative/. We should have some basic support
infrastructure built up around our solar system. So many things would be
easier and new avenues opened.

------
doodlebugging
So, an interstellar dust bunny.

I wonder if it will find a resting place in some dark corner of the universe,
maybe behind a black hole somewhere just out of our sight clinging tenuously
to the outstretched arm of some far-off spiral galaxy and resisting every
effort to slurp it back into the vacuum.

~~~
Grimm665
Your comment made me smile.

~~~
doodlebugging
Thanks. It doesn't add much to the discussion but I thought at the time that
it might be a reasonable analogy based on the author's speculations. Of course
we may also have just missed the opportunity to save the Who's. Sadly though,
they couldn't all yell loudly enough for us to hear them over here on our
rocky speck.

~~~
rbanffy
Can we please name the space probe we'll launch to explore it "Dyson"? After
Freeman Dyson, of course.

------
ChuckMcM
Not that I get my science from SyFy but this particular hypothesis of a
ice/dust composite doesn't survive the 'thermal / tidal' test. Which is that
an object of that density would deform due to the tidal forces imparted by the
Sun as it changed direction. I've yet to see a paper that suggests its profile
changed at all before, during, or after the solar system transit.

~~~
joering2
In Oumuamua defense, it hasn't seen this much of Sun to be impressed or
inflicted by its thermal power. 25. kilometers. per. second. It went in and
out before Sun could do its damage.

However, the idea of a porous surface like a snowflake or sponge or something
doesn't add up because of exact speed it travels. Even if this is just
ice/dust composite, with that kind of speed, it would be disintegrated by
having its surface polished with cosmic energy long before it could reach
25km/s.

I hope we won't see another one. This one was so close to Earth it wasn't
funny. And traveled so quick we wouldn't have time to call all family members
to tell them we love them. Its nothing like meteor; even big one would just
drop flat on earth, raise all dust for next 30,000 years, throw us back into
stone age or close to extinction and some form of human life looking nothing
like we do today would argue 250,000 years from now what caused the first
human near-extinction. No. You're talking about razor-sharp thin and
lightweight object traveling with insane speed. Upon impact, it would either
penetrate Earth surface exploding inside the core, like any hollow bullet
does, or it would cut Earth in half like a high power laser and deform itself
on way out. Either way this wouldn't be your near extinction experience. This
would be like all of sudden Earth spliced in half and both parts going away,
while you are either being drown with oceans hundreds feet of water tall due
to lack of gravity, or crushed by weight of same ocean who happened to froze
in the upper atmosphere, caught some gravity and smashed on the top of you. I
don't want to even think about super hot lava thrown everywhere without
gravity it would be like spraying venom from a giant snake.

I have no idea how something like that would look like when Earth split in
two, and no movies of that kind of extinction has ever been done. But
something tells me it would be far from an easy death and I would rather carry
on suicide pill in my tooth like they did during WW2, rather than witness such
literal Hell on Earth.

~~~
thatcherc
This is all predicated on 25 km/s being very fast, which in this case it
really isn't. Man made objects like the ISS travel at 7 km/s, so these are
relatively achievable speeds, even for humanity.

We can look at meteor impacts, too. The first source I found on the topic said
meteors commonly impact with 11- 72 km/s. [1] This happens every day with
small objects and we're fine. With bigger objects you'll get extinction events
and features like the Chicxulub crater, but no way you'd see anything
"penetrate Earth surface ... like any hollow bullet does, or ... cut Earth in
half like a high power laser."

The speed of light is 300,000 km/s, more than 10,000 times faster than
Oumuamua. An object at 0.1c or even 0.01c would be very threatening, but those
are still orders of magnitude faster than Oumuamua.

In short - 25 km/s isn't that fast, don't worry about it. There are plenty of
asteroids that could hit us faster than that that we also don't always see!

[1] - [https://www.amsmeteors.org/meteor-showers/meteor-
faq/](https://www.amsmeteors.org/meteor-showers/meteor-faq/)

~~~
joering2
We still don't know what Oumuamua is made off of. I think we can agree anyone
would rather be hurt by a baseball flying 10km/hour, than being hurt by a
knife that travels 1km/h.

~~~
dragonwriter
> We still don't know what Oumuamua is made off of.

The fact that it is tumbling and not coming on like a dart along it's long
axis means it pretty much doesn't matter what it's made of, aside from it's
total mass, it's not going to do some kind of radical penetration or anything
else that unusual of it were to hit the Earth.

(Even if it was a stabilized penetrator dart of some kind, AFAIK, that doesn't
really change much about surface impact unless you make radically implausible
assumptions of composition, but I think it might effect the probability of it
making a ground impact rather than an airburst.)

------
mel919
The whole situation of us encountering Oumuamua and being unable to gather
much information about it reminds me of one of the Lem's short stories about
Pilot Pirx in which he encounters an unique alien object and is also
struggling with recording data about it.

Here's a quote that works on imagination:

There are times when the human eye can behave like a camera lens, when a
momentarily but brilliantly cast image can be not merely recalled but
meticulously reconstructed as vividly as if viewed in the present. Minutes
later, I could still visualize the surface of that colossus in the flare’s
afterglow, its kilometers-long sides not smooth but pocked, almost lunar in
texture; the way the light had spilled over its corrugated rills, bumps, and
craterlike cavities—scars of its interminable wandering, dark and dead as it
had entered the nebulae, from which it had emerged centuries later, dust-eaten
and ravaged by the myriad bombardments of cosmic erosion. I can’t explain my
certainty, but I was sure that it sheltered no living soul, that it was a
billion-year-old carcass, no more alive than the civilization that gave birth
to it.

This story (Pirx's Tale) is available on Google Books:
[https://books.google.com/books?id=n16z06cm1P0C&lpg=PT11&dq=%...](https://books.google.com/books?id=n16z06cm1P0C&lpg=PT11&dq=%22Sci-
fi%3F%20Sure%2C%20I%20like%20it%2C%20but%20only%20the%20trashy%20stuff.%22&pg=PT11#v=onepage&q=%22Sci-
fi?%20Sure,%20I%20like%20it,%20but%20only%20the%20trashy%20stuff.%22&f=false)

------
GlenTheMachine
I'm curious about whether an object with a density this low could survive the
gravity gradient it experienced during the solar flyby.

~~~
ars
Unless it's very large why would there by much of a gravity gradient?

It never came all that close to the sun, so the gradient on different parts of
it wouldn't be that extreme.

~~~
GlenTheMachine
There wouldn't be a large gradient. But a big ball o' fluff presumably has
essentially no internal cohesion; it's sort of like a liquid in that way. So
even very small gradient forces could be enough to disperse it.

~~~
ars
So lets run the numbers:

At Perihelion it was 38198320 km from the sun = an acceleration of
0.090962666582226 m/s^2

It's 1km long so on the other end the acceleration is 0.090962661819574 m/s^2

Subtract: .000000004762652 m/s^2 which is such a small amount I'm not sure how
to put it into context.

Multiply by 1 metric ton = 1/5 weight-force of a single snowflake on earth.

Which means each metric ton of material needs to handle just that much force
trying to separate it.

i.e. it won't be ripped apart in the slightest. Over centuries it might
elongate a bit (and it's already elongated).

~~~
GlenTheMachine
Interesting. Thanks for the analysis.

So, continuing this general line of thought: what's the largest tidal force it
would have experienced? Differential solar pressure? Would it have encountered
anything on its journey that should have dispersed it?

~~~
ars
> what's the largest tidal force it would have experienced?

I have no idea of its past obviously, but near us this would be it, at closest
approach to the sun the tidal force is greatest.

> Differential solar pressure?

Solar pressure is very low, it just applies that force for a very long time.
It would act to compress it (flatten it), slightly.

But I don't know what orientation it had when approaching the sun. It could
have been tumbling and randomized any force.

> Would it have encountered anything on its journey that should have dispersed
> it?

Vaporization from heating is the only thing energetic enough that I can think
of.

But maybe other people can think of other things.

------
excalibur
I don't know that this theory is any "weirder" than an alien spacecraft, but
it's certainly more plausible.

~~~
arxpoetica
Plausible or less deniable?

------
jl2718
Meteorites form in distinctive nickel-iron crystal patterns (Widmanstatten). I
wonder if they would form ‘snowflake’ patterns in conditions of large negative
temperature and pressure gradient following a supernova shockwave.

------
booleandilemma
It frustrates me to no end that there was a possibility (however small) that
we could have witnessed an alien artifact passing by our planet and _we missed
it_.

------
27182818284
The idea it is a fractal structure is not weirder than the idea it is possibly
an alien probe sent over the course of hundreds of thousands of years to pass
by our Goldilocks-zoned planet for observation.

Does anyone know more about the initiatives by Yuri Milner with respect to
this? I heard something like he is helping fund satellites that could
specifically be better at looking at 'Oumuamua than our current means?

~~~
magduf
We can't look at 'Oumuamua any more, with any kind of spacecraft. It's headed
out of the solar system. There's absolutely no way we could possibly put
together a mission and build a craft and launch it and have it catch up with
'Oumuamua at this point. If we had something ready to launch _now_ , it might
be possible to catch up with it, but it would be years before we could have a
mission ready to go, and we don't have the propulsion technology necessary to
catch up with it after that much time.

This should have been a big wake-up call to have pre-made probe craft ready to
launch to investigate anything odd that entered the solar system. But
expecting humanity to be that fore-sighted is pure folly.

~~~
jandrese
Oumuamua is traveling at 26kps. For comparison the Voyager probes are
traveling at around 17kps.

Even if we had a probe ready today it's already too far and moving too fast to
overtake. Even if we had a probe ready when we first detected the object it
would have been difficult to intercept with today's technology. It would have
to be something like a Falcon Heavy already in orbit and ready to burn at a
moment's notice with a tiny probe at the top for gathering the data.

~~~
jacobush
So it follows we should have that, at all times. :-)

~~~
captncraig
That payload is... a lot of teslas worth of cargo. It would need to be built
in orbit. A project that size would definitely make a lot of jobs and require
a major rebuilding of our space problem. So many downsides.

------
kirykl
Weird still is "Oumuamua's velocity (being) within 5 km/s of the median
Galactic velocity of the stars in the solar neighborhood"
([https://arxiv.org/abs/1710.11364](https://arxiv.org/abs/1710.11364))

That means the system it originated from if a natural object would need to be
coincidentally that close to our median local

------
Mizza
What are the hypothetical requirements of a craft/probe which could be sent to
chase after this object? Could we build something very small but extremely
fast perform a fly-by? It kills me to think we've been visited by a mystery
I'll never get the answer to in my lifetime.

~~~
sp332
Yeah, it's slow enough that we could catch up to it. One of the biggest
mysteries about it is why it was moving so slowly. Voyager left the solar
system at 17,000 m/s. ‘Oumuamua accelerated to a top speed over 87,000 m/s as
it was moving toward the sun, but it's slowing down now, and will eventually
slow to 26,000 m/s. It will pass the orbit or Uranus early next year.

~~~
jandrese
Note that the Voyager probes are only moving that fast because they got
orbital assists. It would take a very big rocket already in orbit to attempt
an intercept.

~~~
sp332
Oh it would be crazy expensive. But we have the tech. (Wait, do we have tech
for in-orbit refueling? Anyway we're developing that for Mars missions already
so we'll have it soon.)

~~~
lucb1e
We resupply the international space station, so even if we couldn't carry
great loads of fuel up at a time, orbital refueling is clearly within the
realm of the possible.

More interesting would be if we could beam up energy to refuel, but for that
we'd probably need yet-to-be-invented drives which use loads of energy per
amount of matter to accelerate it further. Kind of like a particle collider
but for propulsion.

------
billbrown
The main proponent of the Oumuamua is an extra-solar object is Harvard
astronomer Avi Loeb and there's a great interview with him where he discusses
his reasons for his conclusions in a very accessible manner:

[https://after-on.com/episodes-31-60/040](https://after-
on.com/episodes-31-60/040)

------
pjungwir
Isn't extra acceleration what dark energy is supposed to explain? (Maybe
"explain" is the wrong word. :-) I haven't seen anyone say this (probably for
some good reason), but maybe 'Oumuamua's acceleration is from the same source?
I'm curious what more knowledgeable people have to say about that.

~~~
saagarjha
The "acceleration" dark energy is supposed to explain is with regards to the
expansion of the universe, which would have very little effect on anything on
scales this small.

------
Jeff_Brown
The argument "it's too slow to be a spaceship" makes a lot of unstated
economic assumptions. Yes, a bigger sail would be faster. But if you wanted to
send a lot of ships to various places, and you were the kind of civilization
that makes very long-term investments, smaller probes could be optimal.

------
dwighttk
I feel like the headline writer tried to spice it up a bit and went too far.
Seems _much_ less weird than alien artifact to me.

I mean I'd click on an "Another Oumauamua Theory" headline, but I guess that's
not what kids are clicking on these days.

------
slg
I am just a layman, but it sounds like an object of this structure would be
relatively fragile. Would it be able to survive the type of event that would
be needed to launch it into interstellar space at the speed it is traveling?

~~~
jandrese
If the object is a loose collection of dust it might very well be the result
of something that _didn 't_ survive whatever event created it.

~~~
LeifCarrotson
What a tragedy that would be to catch it, find that it was created by some
extrasolar intelligence, but it's been destroyed.

------
rayvd
Makes me think of Rendezvous at Rama[1].

[1]
[https://en.wikipedia.org/wiki/Rendezvous_with_Rama](https://en.wikipedia.org/wiki/Rendezvous_with_Rama)

~~~
mud_dauber
I came here for exactly this comment. Props.

------
Quequau
OK this is great.

I never gave a moment's credence to the idea that it was an alien spaceship
but I really enjoyed reading the thoughtful and well reasoned arguments for
and against the idea. For me the space of thought that these arguments created
was an interesting experience that gave me an interesting perspective.

So saying "hey no, it's not spaceship... it's weirder than that" (and then
arguing that point) is fantastic.

~~~
bgroins
Coming from a planet that launches a lot of alien spaceships, is it that
implausible that it could be (or could have been) an alien spaceship?

~~~
xeonoex
This. I don't understand why articles like this are so quick to dismiss the
chance that it was an alien probe or ship. I feel like it's just to get clicks
and make the hypothesis they present seem more plausible.

I totally agree that there is a good chance that it wasn't alien, and we want
to identify what it could be if it wasn't, but why dismiss it? Most scientist
already believe we are not alone, even though it is unlikely we are close to
any other intelligent life. The chance that it was alien should be explored as
well, and I know their are scientist who believe it is alien.

------
buboard
But ... i thought amazon is going to produce the new series of the Expanse. Or
is SYFY going to fork the story with a 'deuteromolecule' ?

------
eof
I don't find the author's reasoning in the related article[1] that its not a
solar sail very convincing. I am not an astrophysicist, but, the author
plainly admits that the measurements are within expected bounds of a solar
sail.

Instead, the argument is surrounding the psychology of the hypothetical
creators of said solar sail, or plausible ways we missed some data. Since we
are just speculating at this point, who am I to say?

But to answer some specific criticisms:

\- Perhaps the brightness/darkness cycles were the sail turning on and off as
a mechanism to control velocity

\- Perhaps the 25km/s speed being a crawl for interstellar travel was because
it was meant to slow down while passing through our solar system. Either so we
might notice it, or so it can collect data while here a bit better.

I am having a hard time understanding how rare an event this space-foam-
fractal theory is predicting, but if it's extremely rare a solar sail seems a
completely reasonable hypothesis still.

1\. [https://www.syfy.com/syfywire/is-oumuamua-an-interstellar-
sp...](https://www.syfy.com/syfywire/is-oumuamua-an-interstellar-spaceship-im-
still-going-with-no)

~~~
lubujackson
It's the "I don't want to say aliens because no one will listen to you if you
say aliens" conundrum, which does a disservice to the science by pooh-poohing
any intelligence-spawned possibilities while wildly speculating on naturally-
caused possibilities.

The reality is this is an extremely alien object, no matter if it was formed
by intelligent beings or spun off from a star. Maybe this is a solar sail or
maybe it is a giant snowflake.

And, contrary to the author's hand-waving, there is nothing that says an
enormous, impossibly thin solar sail can't be formed by randomly bashing an
infinity of rocks together over a near-infinity of time - after all, LIFE
ITSELF comes from just such an action, so pretty much anything is in play if
that is the standard!

~~~
daeken
> after all, LIFE ITSELF comes from just such an action, so pretty much
> anything is in play if that is the standard!

That's how _an instance of life_ came about. A very simple, most likely
extremely short-lived, not at all efficient form of life. The advancement to
Eukaryotes took ~2 billion years from there, and multicellular life took about
another billion years. These happened not by random bashing, but selection
pressures.

While a solar sail could happen completely randomly, 'life itself' isn't
really a good comparison, since that's not really how it happened. At least
not any form of life that is really recognizable as life.

~~~
rickycook
everything is randomly bashing things together; every human is randomly
bashing things together. we are similar, but have billions and billions of
tiny differences that make up the specific things about us.

everything has selection pressures too: just like life forms exist and thrive
in different environments, dust behaves differently at different temperatures
and gravities.

life as an event, and specific things that happen thereafter are no less
“random” than specific chunks of rock/dust in specific configurations

~~~
kochikame
> life as an event, and specific things that happen thereafter are no less
> “random” than specific chunks of rock/dust in specific configurations

No. Incremental changes over millions of generations in response to
environmental pressures are not "random".

This sliver of dusty ice may have formed in a one-in-a-million random chance,
but there's no process that selects for this.

------
dontbenebby
One of the embedded assumptions I seem to see in discussions about this object
is that objects like it (from outside the solar system) are rare.

Is this truly the case, or is it just hard to monitor the paths of the
multitude of objects passing by earth?

~~~
tericho
It is rare because other systems that form these objects are VERY far away
(trillions of KMs). Imagine trying to slide a hockey puck from one end of a
hockey rink to the other, but have it pass through a small (~1M) circle at the
far end from you. If you took 1000 attempts even randomly, you'd probably hit
the circle by accident at some point. Now someone else is also shooting at the
circle, but they are 50,000KM away. Suffice to say no matter how many attempts
that person takes, it will be significantly more rare to see their puck cross
through the circle than yours.

------
arxpoetica
> It seems far more likely that objects like 'Oumuamua are relatively rare,
> and that means it likely came from someplace close by (if it came from
> farther away, the odds are even lower we'd ever see one).

Rare enough to be a space ship?

~~~
SahAssar
Given that we don't know if interstellar spaceships exist I'd say calling them
"rare" is a misnomer.

------
dkonofalski
So... in the time in the US where both sides are yelling at each other about
being special snowflakes, we have the largest snowflake ever observed just
floating by. What a weird coincidence and what a time to be alive!

------
jypepin
Ok, I know nothing about space, but looking at this video, it makes me realise
something.

Would have it been possible for thie Oumuamua to directly crash into the sun
and just... end our solar system? Just like that?

~~~
Cthulhu_
I guess it would be possible that it crashed into the sun, if it had the right
trajectory, but it wouldn't have had any effect; the thing is 50 - 130 meters,
while the sun is nearly 900.000 KILOmeters in diameter. It would likely have
burned up before even reaching the surface of the sun. Even if it was idk, a
huge nuclear weapon that detonated before melting, it wouldn't matter because
the sun already is a huge fusion nuke. It does coronal mass ejections
regularly that, according to a pop sci article I just read, already has more
energy than 20 million nuclear weapons - anything that would end the sun would
have to be several orders of magnitude stronger.

------
coolspot
> Assuming a size for 'Oumuamua of 50 – 130 meters, what they get is a very
> low density: About 0.00005 grams per cc.

Do we have example of naturally ocurring space object with such low density?

Half-close? Quarter-close?

~~~
Symmetry
Even an aerogel is .0.2g/cc. That sounds implausible to me but so does the
solar sail hypothesis. And really we don't have much information about what an
interstellar object would be like.

~~~
gus_massa
I agree that the proposed density is too low. Anyway, the aerogels are deigned
to support their own weight on Earths, wind currents and some moron poking
them. The magical aerogel of this object may have lower requirements.

------
darklighter
This is ridiculous. It’s intergalactic debris, it could be anything.

I would prefer to see a list of things it could be vs. the hubristic response
of leading scientists.

It’s a great example of something unknown.

~~~
zapzupnz
> I would prefer to see a list of things it could be vs. the hubristic
> response of leading scientists

But isn't it through what leading scientists deem it could be that we get such
a list that you want?

Otherwise, it could be:

\- an icy fractal aggregate

\- a rock

\- a teapot

\- a bunny rabbit

\- a full-scale replica of the Titanic visible only to bees

\- a fortnight's holiday in Benidorm

------
DoctorOetker
what I don't understand is this: if the kinetic energy is higher than the
potential energy, what is the probability that it would pass the sun so
closely? for bound objects this is not so surprising.

either these objects are way more frequent than we think and the reason it
passed the sun so closely was simply that these would be the first to be
observed, or it almost seems aimed to pass the sun closely?

~~~
yesenadam
We do think they're very 'frequent':

"Astronomers estimate that several interstellar objects of extrasolar origin
(like ‘Oumuamua) pass inside the orbit of Earth each year, and that 10,000 are
passing inside the orbit of Neptune on any given day."

[https://en.wikipedia.org/wiki/%CA%BBOumuamua#Other_interstel...](https://en.wikipedia.org/wiki/%CA%BBOumuamua#Other_interstellar_objects)

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jimijazz
Is it technically correct to call 'Oumuamua an UFO? I mean, it is unidentified
so it should apply, right?

~~~
rbanffy
Considering its trajectory is more or less ballistic, the F would stand for
"Falling".

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sandymcmurray
Disk Not Ejected Properly Eject "Oumuamua" before disconnecting or turning it
off.

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airstrike
Fans of The Expanse have known what it is all along...

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apotatopot
It's not fat, it's fluffy.

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fizixer
paper:

> [Oumuamua as a fractal] is a hypothesis worth investigating ...

tabloid journalists:

> NO, 'OUMUAMUA IS NOT AN ALIEN SPACESHIP ...

I guess the use of 'Bad Astronomy' tag is apt.

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Pristina
It's probably an alien probe disguised as a random rock. It's already
transmitted the existence of Earth and its coordinate back to the homeworld.
Soon a supernuke will be sent at 0.99C to nip humanity in the bud.

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gammateam
None of this rules out the idea that it is a vessel and or from a civilization

Its not mutually exclusive

Its just clever and now we have hypothesis about how it was done

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siavosh
Off topic, on the writing style: the personal casual style that sprinkles
things with "I have to say, I love this." seems to have become incredibly
common now in news sources. What's led to this? I always feel like it detracts
from the story, and adds nothing unless they've AB tested it and it helps ad
revenue?

~~~
Brendinooo
This is a blog, right? Blogs have always been more informal.

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gammateam
This was an amazing deduction.

I dont understand the key component of the article about the radiation from
the sun giving it a boost. These scientists were able to make all these
deductions about its shape and why from this, but what? How does radiation
propel in any circumstance? Are we saying molecules change composition?
Electrons moving to another state? What

~~~
LyndsySimon
> How does radiation propel in any circumstance?

It depends on the type of radiation, but two mechanisms jump to mind for me:

The first is direct action of photons, as in a Crookes radiometer. The idea is
that the black and white sides of the vanes respond to different types of EM
radiation differently. How it _actually_ works is somewhat beyond me (and
apparently contentious), but it does work:
[https://en.wikipedia.org/wiki/Crookes_radiometer](https://en.wikipedia.org/wiki/Crookes_radiometer)

The second is is through boiling. If the side of the object facing the sun
were composed of a material that boiled when exposed to sunlight, the boiling
off of that material would provide thrust against the object in the same way a
rocket provides thrust (by expelling gas).

Note that I am not a physicist, and am not proposing that either of these are
the reason for the object's anomalous trajectory - just throwing out two ideas
through which radiation could propel an object.

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LifeLiverTransp
Seriously- its a snow-flake, as in something snow bally like Halley's Comet -
that would emit vapours under light pressure? What is this, if you disprove
your own thesis in the prelude of your article? Scientific slapstick?

~~~
jandrese
Sounds like it might be a giant rock-dust flake. Maybe the whole thing is held
together by vacuum welding?

~~~
jerf
If you imagine a dirty snowball, then sling it past a star so that all the ice
melts and leaves, you might be left with something vacuum welded together, but
very fluffy for its size. Perhaps the same time that it lost all its volatiles
is also what ejected it from some system, a slingshot around some other star.

~~~
jandrese
That wouldn't be terribly different from how Aerogels are made.

