I need this condensed into about 3 minutes if you can. :: A researcher there, Robert Weryk picked an object up 40 days after it made its closest
approach to the sun.
This object has turned out to be very strange indeed, and continues to fire debate to this
day.
From the moment of its discovery, the mystery of Oumuamua has only deepened.
When the object was first spotted, it was very close to earth, only about 85 times the
distance of our moon, or .22 astronomical units, and it had already passed its closest
point to us, which was only about .15 AU.
The sun, for comparison, is about 1 full AU from us, roughly 93,000,000 miles.
Needless to say, this was a very close flyby of our planet by an object in terms of the
size of the overall solar system.
But, it’s worth nothing here that objects do pass much closer.
For example, in 2004, a very small asteroid passed earth at only about 1/10th of the distance
to the moon.
There have been even closer calls, with another such object grazing the earth’s atmosphere
in 1972 where witnesses in western North America saw a huge fireball and heard double sonic
booms only to then watch the fireball leave the atmosphere and head back out into space.
It simply came in at too shallow of angle to hit us, but did enter the atmosphere.
But, as the great Chelyabinsk fireball of 2013 showed, or Arizona’s Barringer crater,
objects from space do also smack squarely into us fairly regularly.
Oumuamua, however, was never in any danger of doing that and never will be.
While it passed close, it didn’t pass dangerously so.
Originally classed as a comet, and then an asteroid when no coma or off gassing characteristic
of comets was observed, it then quickly became evident that the object was neither a normal
run of the mill comet nor an asteroid originating from our solar system based on its trajectory.
Instead, it came in at a very odd angle and speed, which was hyperbolic, meaning it almost
certainly had to be of interstellar origin.
it was likely that this object had originated in another star system entirely.
This led the International Astronomical Union to come up with an entirely new classification
to fit this object, the I in 1I/2017 U1 stands for Interstellar.
It was then given the name ‘Oumuamua, translating in Hawaiian to roughly “first distant messenger”,
though the name Rama was, as i mentioned, also floating around after Arthur C. Clarke’s
novel, Rendezvous with Rama and subsequent installments of that series.
It’s anyone’s guess which name is more fitting, since in the months after it’s
discovery, murmurs of a possible, though highly unlikely, alien origin for this object have
surfaced within some parts of the scientific community.
But before we move on, let’s first talk about the interstellar nature of the object.
Is it really from another star system?
The answer is yes.
Up until recently, there was still a chance it was not.
It was possible that something in the outer solar system might have tossed Oumuamua into
a hyperbolic orbit, and that it’s origins could have been our own Oort cloud.
This now seems discounted, and the physics of Oumuamua seem to exclude it from being
from here.
So, if interstellar, the natural question here is to ask what the origins of Oumuamua
might be.
This is, unfortunately, very murky.
While Oumuamua came from the direction of the star Vega, one of the brightest in the
night sky that does happen to have a debris disk, it doesn’t appear to be related to
it and couldn’t have originated there.
Rather Oumuamua may have originated from very, very far away, a very long time ago, with
some estimates that before encountering the solar system, the object may have circled
the Milky way multiple times over immense amounts of time.
Given that the origins of Oumuamua are probably a matter of ancient history, retracing its
steps backwards to its origins seems an impossible task, in the same grain as reconstructing
the exact movements of a game of billiards that was played a hundred years ago by only
knowing the trajectory of the last shot.
Not enough information is preserved to reconstruct the whole game.
Same story with Oumuamua.
But there are some other possibilities.
In a paper by Coryn Bailer-Jones and colleagues, link to all papers mentioned in this video
in the description below, several marginally possible origin candidates are advanced, though
the paper itself warns that none of them are particularly good and in coming years many
more candidates may come to light … though those may not be particularly good either.
The study looks at reconstructed close encounters Oumuamua recently had, at least geologically
recent.
One of these was with a red dwarf about a million years ago, and another with a Type
G5 dwarf about 3.8 million years ago.
It’s possible that within these systems Oumuamua might have been ejected by a gas
giant, though none of these systems are currently suspected of having planets, so it more likely
simply passed through them, though not as near is it passed our sun.
Perhaps a better option, given the velocities of Oumuamua, is a binary star system, though
no good candidate for a binary star system in Oumuamua’s reconstructed recent path
has yet been found.
But the dynamics of such a system might account for Oumuamua’s behaviour.
More likely is that Oumuamua has been wandering the galaxy for immense amounts of time, in
such case its origins will probably never be known.
In a paper by Q. Zhang, the idea of further trying to backtrack Oumuamua’s path is covered.
The problem of tracing the origins of any interstellar object is discussed, and while
data releases from GAIA spacecraft and other sources will make the task a little easier,
it will still be difficult if not impossible to trace any object’s path backwards more
than a few tens of millions of years.
That’s about the best we’ll be able to do for Oumuamua and future interstellar object
discoveries.
However, for objects more recently ejected from their star systems, we may have occasional
success.
For example, it’s known that the relatively nearby young star Beta Pictoris has a huge
debris disk that’s ejecting material that seems to be passing through our solar system
constantly.
That system is also known to have comets, so if one happens to get ejected and sent
our way, we should in principle be able to pin down Beta Pictoris as the origin should
that happen.
One final possibility, at least out of those that scientists have thought of so far, is
particularly interesting.
That Oumuamua may not have been ejected from a run of the mill star system, but from a
more exotic source.
In a paper by Roman Rafikov, the idea that a white dwarf could produce tidal disruptions
of rocky planets and planetoids ejecting material like Oumuamua, or even ejection during a supernova
event.
This is due in part because of the odd apparent physical traits of Oumuamua, more on that
in a minute, but ultimately this is probably a less likely scenario than an ejection from
a binary star system long ago.
Regardless of the origins of Oumuamua, as the story unfolded it became apparent that
this object wasn’t just interesting due to its potential interstellar nature, but
also its shape.
As it turns out, Oumuamua is like nothing else we’ve ever seen as far as objects in
our own solar system are concerned.
The first hint that something wasn’t quite normal with this object came in the form of
a very unique light curve that showed that Oumuamua brightened and dimmed relatively
rapidly as it moved through the solar system.
Initially this was thought to be due to Oumuamua being a very elongated object that was tumbling.
Essentially a cigar shape that reflected more light at times as it rotated about once every
8 hours.
Another possibility is that it was a very flattened object, something like a pancake.
In a paper by Karen Meech and colleagues, they detail many of the strange aspects of
this object.
Also, for those interested, I recently interviewed Dr. Meech on my second channel, Event Horizon,
link to that show in the description below and in the end screen.
Then there is the nature of the object.
Initially, Oumuamua was suspected of being a comet.
The problem is, a comet passing as close to the sun as Oumuamua did, should have outgassed
as volatile ices evaporated blowing dust off the surface and forming a coma and tail, as
in a normal solar system comet.
The researchers note that no such cometary activity was seen with Oumuamua, and if it
were a comet, there’s no reason that the volatile ices it contained wouldn’t last
billions of years as it crossed space.
Yet, the composition of Oumuamua, based on spectroscopic study, show that the surface
of the object appears very similar to objects in our own solar system, some of which incidentally
happen to be rich in organics.
But there’s a further mystery here.
If interstellar comets are common, it seems likely that in the last few hundred years
that we’ve been able to work out cometary orbits, we’ve yet to see one and we should
have.
Such objects should be relatively primitive, ejected from extra-solar Oort clouds.
That would mean that their ices should be fully intact, and encounters with stars rare.
So if one did enter the solar system and approach the sun, it should have produced a detectable,
possibly even spectacular, comet tail as objects from our own Oort cloud do, yet be on a hyperbolic
trajectory indicating an interstellar origin.
That has never been seen.
But the idea of extra-solar comets passing through the solar system is an interesting
idea in itself, because of the organics they may contain.
Comets are a candidate for having delivered the building blocks of life to earth.
There are even meteorites that are thought to be cometary in origin that contain amino
acids.
While there’s no reason to suspect this happened with earth, it’s possible that
interstellar objects may play a role in the universe in seeding exoplanets with the building
blocks for life to get started.
And it may also be possible, given the right circumstances, for these objects to seed life
itself through panspermia.
On the other hand regarding extra-solar comets, there are currently two candidates in our
solar system that may have once been interstellar comets.
But it’s unclear how old they are, or when they were captured.
So perhaps comets passing through the solar system are uncommon, but not particularly
rare.
Or, perhaps it’s just a fluke that we haven’t seen one, and in coming years, one might yet
pass through.
But if Oumuamua isn’t a comet, then the natural alternative would seem to be an asteroid,
though the line between an exhausted comet and an asteroid is rather thin.
But it doesn’t seem likely that Oumuamua would be an exhausted comet, rather that it’s
more likely that this is the closest it’s ever approached a star and outgassing should
have been clearly evident.
It wasn’t.
An asteroidal nature for Oumuamua would be a bit more surprising however, since asteroids
are thought to be significantly more rare in the universe than comets, based on what
we know about the formation of star systems.
Add in the odd shape of Oumuamua — no other like object has been seen in the solar system
to date — and we have an object that stops fitting neatly into either category.
That puts Oumuamua potentially into odder, more unconventional territory.
One possibility is that Oumuamua might be a fragment of a tidally disrupted planet,
in other words a shard of material from a destroyed world.
That would make Oumuamua a much rarer object in the universe than a comet or asteroid,
enough that it should probably be intercepted and studied, since we aren’t likely to run
across things like that every day, in fact, it could be thousands of years before such
a thing is seen again.
But, there’s one last possibility on the table, unlikely thought it is.
This is where the story of Oumuamua takes an even more bizarre turn.
As noted by Dr. Meech in her TED talk on this object, it can’t be ruled out, no matter
how remote the possibility might be, that Oumuamua may instead be of artificial alien
origin.
That’s not to say that it is, it probably isn’t, but simply that it cannot be ruled
out.
But the story of Oumuamua grew even stranger in late June of 2018.
In a paper by Marco Micheli and colleagues, they detail the discovery that Oumuamua accelerated
as it left the inner solar system.
Accelerated is perhaps too strong of a word here, it’s more like Oumuamua left the solar
system less slowly than it should have given the gravitational effects on it from the sun.
This would seemingly have a mundane answer; that Oumuamua was in fact a comet even though
it didn’t entirely look like one.
Cometary outgassings can act as a kind of natural thruster and impart a bit more speed
to an object than the effects of gravity alone can account for.
The problem is, no such outgassing was observed with Oumuamua.
It could possibly be that we somehow simply missed it when it happened, or that it was
imperceptibly slow, or that the outgassing was difficult to detect with the data we have,
such as outgassing from pure water ice, but that still should have blown off dust which
should have been detectable.
And, there’s another issue.
Given Oumuamua’s odd shape, any outgassing should have upset it’s tumbling and that
should have been detectable, though it’s also possible that the outgassing came from
a point on the object where it wouldn’t have changed anything.
But, more recent research by Rafikov shows that it’s likely that any kind of outgassing
should have changed Oumuamua’s rotational torque enough to destroy it.
This mystery has since further deepened.
In November of 2018 in a paper by David Trilling and colleagues, again link below, they detail
the results of an observation, or more precisely a non-observation, of Oumuamua using the Spitzer
space telescope.
By non-observation, I mean that they looked for the object in infrared and didn’t see
it.
That in itself is telling because they should have.
It means that Oumuamua must be very small, on the order of hundreds of meters in size.
This is odd indeed, because to have been seen at all in the earlier observations, it would
require Oumuamua to also be very highly reflective, unusually so.
As Oumuamua revealed itself to be an increasingly strange object, the notion that it may be
of alien origin has been increasingly looked at, remote though the possibility is.
SETI teams, for example, just to be sure, listened to Oumuamua for radio emissions.
None were detected.
And while it’s highly unlikely for this object to be of artificial origin, it’s
very likely a weird natural object, accumulated weirdness surrounding this object is raising
some eyebrows.
In a paper by Abraham Loeb of Harvard, he details six of these strange attributes of
this object.
He points out that Oumuamua should never have been discovered in the first place.
This is based in an earlier paper co-authored by Loeb where it was predicted that the abundance
of interstellar asteroids would be too small for it to be likely that we’d just happen
to catch such an object serendipitously as happened with Oumuamua, meaning that whatever
spawned Oumuamua must be more common than what we see with our own solar system.
Loeb also points out that Oumuamua originates from a weird frame of reference, the LSR or
local standard of rest.
He goes on to point out that this is ideal if you want to camouflage an object if you
want to hide its origins, though it’s also possible that Oumuamua has just been wandering
so long in the galaxy that it simply settled into this frame of reference.
But there’s more.
Oumuamua would have had to leave it’s star system of origin with an unusually high velocity,
meaning that whatever the circumstances of it’s ejection were, they are very likely
rare and unusual.
Also, there’s the shape, Oumuamua would have to have a length at least 5 times its
width, or possibly as much as ten.
The most we’ve seen with solar system objects is three.
And then there is the Spitzer observation, which means the object must be small, and
lastly there was the unexplained acceleration.
These attributes led Bialy and Loeb to author a paper that the acceleration could be due
to solar radiation pressure, if Oumuamua were very thin, a millimeter or less.
This begins to look consistent, and I stress that, look consistent, with a light sail of
artificial origin.
For it to be that, it would have had to have been targeted towards our solar system.
Standing for that possibility is the age of the earth.
Earth’s oxygen has been visible to the galaxy for a very long period of time, well enough
for astronomers from other star systems to have spotted Earth as an exoplanet, and concluded
that the unusual amounts of oxygen in our atmosphere was most likely the result of a
biosphere.
Perhaps at some other point they might have found further evidence through the detection
of other biosignatures of life on this world and sent a probe.
Also marginally going for it would be the acceleration, which is still unexplained,
but slow outgassing from a natural object seems far more likely there.
Standing against it are several things.
Firstly, what are the chances of just happening to spot an alien probe just as it passed through
the solar system?
Not very likely, unless they pass through constantly.
It seems more likely that rocks and ice coming in from interstellar space would be pretty
common, especially if dying stars lose their Oort clouds into space, even if bearing odd
attributes unfamiliar, so far as we know, to objects in our own solar system.
Another issue is that Oumuamua appears to be tumbling, and that doesn’t seem to be
a good fit with a light sail.
Also Oumuamua seems to be traveling counterintuitively slow for an artificial object, it presumably
took millions of years to get here, though who knows how an alien civilization might
perceive time.
Also there’s the apparent consistency in spectral studies of Oumuamua with objects
in the outer solar system, it essentially looks like a reddish object that’s been
bombarded by radiation in the interstellar medium for long periods of time.
On the other hand, it might have accumulated that dust over time.
That’s also a possibility to explain it’s high reflectivity.
If Oumuamua were a piece of water ice that had a layer of material deposited on its surface
, and that material was slowly stripped away during its encounter with the sun, that might
not have been seen, and bright fresh ice might explain the reflectivity.
At the same time, it pays to weigh all options, both natural and artificial.
I personally suspect that Oumuamua is a natural object that encountered unusual circumstances
in past encounters with stars, or within it’s home star system, at least from what we know
from our own solar system.
But, with new instrumentation coming online, more light might be shed on just how unusual
of an object Oumuamua was.
And while it’s close pass to earth is weird, and it might be consistent with an alien light
sail checking us out, it seems more likely that there are many such interstellar objects
passing through the solar system on a constant basis, and if so, many should come to light
when the Large Synoptic Survey Telescope comes online in 2019, with first science light in
2021.
If, however, the LSST does not reveal many such objects, then Oumuamua will fast become
the most interesting object we’ve ever seen, and intercepting it, which would be difficult
but is possible, will become a priority very, very quickly.
Thanks for listening!

In October 2017, astronomer Robert Weryk discovered an object, later named `Oumuamua, 40 days after it passed its closest point to the Sun. This object, classified as 1I/2017 U1, was the first known interstellar visitor, named from Hawaiian for “scout” or “messenger.” Its approach was remarkably close—just 0.15 AU from Earth—and its hyperbolic trajectory confirmed its origin beyond the solar system.

Initial classifications wavered between comet and asteroid. However, `Oumuamua exhibited neither outgassing nor a coma typical of comets, leaving its nature ambiguous. Its unique light curve suggested an elongated or pancake-like shape, rotating every 8 hours. Spectroscopic studies showed surface similarities to solar system objects rich in organics, but its interstellar path and peculiar characteristics deepened the mystery.

Theories about `Oumuamua’s origin ranged from ejection by a distant binary star system to tidal disruption near a white dwarf. Some hypothesized it could be a fragment of a destroyed planet or even a product of exotic cosmic events like a supernova. Its strange acceleration as it left the solar system, without observable outgassing, added to the enigma. Scientists speculated this could result from undetectable outgassing or another unknown mechanism.

Notably, `Oumuamua’s high reflectivity, small size, and hyperbolic trajectory were unusual. While the possibility of artificial origin—like an alien probe—was suggested by some, including Harvard’s Abraham Loeb, no definitive evidence supports this. Observations for radio signals yielded nothing, pointing instead to a natural but highly anomalous object.

The exact origins and nature of `Oumuamua remain unknown. It may have wandered the galaxy for millions or billions of years, making tracing its path back nearly impossible. This discovery highlights the potential for future detections of interstellar objects and their role in advancing our understanding of the cosmos.