The story of 1I/2017 U1 or ‘Oumuamua seems to grow stranger at every passing turn.
Not only is the object the first detected interstellar visitor to our solar system,
it’s also turning out to be very puzzling, to the point that some are suggesting that
it may be of alien origin, though that possibility is not well accepted, it’s just a possibility,
and it’s overwhelmingly likely to be of natural origin.
At the heart of this is the apparent acceleration of Oumuamua as it left the solar system.
To put that in context, Oumuamua simply didn’t slow down as much as would be expected during
it’s encounter with the sun.
It’s not as is if it’s dramatically sped up, it hasn’t.
One possibility to create such an acceleration is that the object is actually a comet, and
outgassing while it passed through the solar system simply gave it a push.
Had this been observed, it would have been case closed, it was an exocomet.
But, this outgassing was not observed, and other recent modeling suggests that Oumuamua
is not quite like a comet.
It’s also possible, however, that the outgassing was slow, or happened when we couldn’t see
it.
But if outgassing wasn’t to blame, then what was?
In a paper by Shmuel Bialy and Abraham Loeb, they detail that light pressure from the sun
could create the observed acceleration if the object had a certain geometry and low
mass.
They also point out that had the object been an outgassing comet, changes in Oumuamua’s
spin should have been observed.
There were no such changes.
They go on to detail that the object’s behaviour could be consistent with a light sail of some
type.
This does not immediately mean artificial however.
The authors detail that to account for the acceleration the object would need to be extremely
thin.
The authors looked at whether such a thin object could survive long distance travel
across interstellar space, along with the mechanical restraints it would be subject
to.
They found that such an object could survive for a substantial period of time, yet be less
than a millimeter thick.
So if the object is acting as a solar sail, it would need to be a thin sheet of material.
If that turned out to be the case, then what created it?
That would be a scientific mystery indeed.
If it’s a natural object, there would need to be some natural process that could create
something like that in a protoplanetary disk or other such conditions.
But, we know from geology on earth, all sorts of strange things can happen to rocks, for
example one form of volcanic rock, known as Pele’s hair, is just such a case.
It’s possible for nature to stretch molten lava into seemingly impossible hair like strands.
Yet it commonly happens.
What could happen out in the universe is anyone’s guess.
But there is another very remote possibility presented in the paper.
That ‘oumuamua could be artificial, and might represent an active or dead probe, or
even simply someone’s trash.
There are two things detailed that seem to support this.
Firstly, if you assume that ‘Oumuamua is just a natural object randomly passing through
the solar system, it may be that the production of such random objects in the galaxy exceeds
what we see from our own solar system for most other stars by a factor of a hundred
million times.
That seems surprising, but not impossible.
But there’s another aspect.
The way the object entered the solar system and passed within a quarter of an AU of the
sun, put it on a good intercept course with earth, which it passed by at just .15 astronomical
units.
Again, that it took a trajectory that might be a reasonable one for an alien probe wishing
to check out earth is a little odd.
But, this too could simply be random chance.
And what’s not well explained is the changes in brightness that were observed with Oumuamua.
It appeared to be tumbling, and it seems to me a light sail wouldn’t work very well
if it were doing that.
The bottom line is that this is only a remote possibility, and that oumuamua is probably
just an odd type of asteroid or comet that we haven’t seen before.
And, also worth noting is that so little is known about ‘oumuamua that more information
may come to light that takes an artificial origin instantly off the table for the object.
We just have to see.
But the fact remains, even as a natural object, ‘oumuamua is very weird and represents a
new class of natural object we’ve never seen before.
Unfortunately, it could also turn out that we may never have a definitive answer to just
what ‘oumuamua was, natural or not, as it is speeding away from us, and it doesn’t
seem likely we will realistically ever be able to intercept it, except perhaps in the
far future.
Also, as an aside, late last night I spoke briefly with Dr. Loeb and we had a conversation
about this paper.
You can hear that interview on my other channel, Event Horizon, link below, and coming soon
will be a full interview with Dr. Karen Meech, one of the scientists investigating ‘Oumuamua
at the University of Hawaii.
Do check them out.
Thanks for listening!
I am futurist and science fiction author John Michael Godier currently worried about Oumuamua
turning around and coming back..
What if something about human civilization enticed ‘Oumuamua to drop by, and then it
didn’t find it during its first pass because it isn’t always present on this world.
Could we wake up to it EMPing us back into the stone age while broadcasting only one
message over and over: “Where McRib?”
-- what a regrettable end to human civilization and on that note be sure to check out my books
at your favorite online book retailer and subscribe to my channels for regular, in depth
explorations into the interesting, weird and unknown aspects of this amazing universe in
which we live.