Just over a year ago, on October 19, 2017 astronomers saw an object from interstellar
space flying through our solar system for the first time.
It was dubbed Oumuamua -- Hawaiian for “scout” -- and almost as suddenly as it had appeared,
it was out of sight again.
Of course we at Seeker covered it and reported that based on what scientists saw they concluded
it was an asteroid.
Now though, they’re not so sure.
There are a few things we can be certain about.
We know it must have come from outside our solar system because it was traveling so dang
fast.
Oumuamua shot past us at almost 88 kilometers per second.
That sort of speed couldn’t have come from the sun’s gravity alone, so it must have
been fired at us from somewhere beyond.
We also know it’s shape, size and.
Color.
It’s likely very elongated, like a stubby cigar, and it’s tumbling through space.
We also know it’s about 400 to 800 meters long and stained dark red, possibly from it’s
interstellar journey.
Everything else about Oumuamua is basically a question mark.
We still don’t know exactly where it came from, but new research just narrowed down
new candidates as Oumuamua’s potential home.
Using data from the European Space Agency's Gaia spacecraft, astronomers identified four
dwarf stars, two that have been identified and two unnamed ones, that Oumuamua might
hail from.
Scientists aren’t convinced yet, because there’s still so much that’s unknown about
it.
But the biggest topic of debate around Oumuamua is what the heck this thing actually is.
Astronomers originally thought it was an asteroid but now they can’t agree because it’s
done some things a comet would do, and there are plenty of reasons to believe it could
be either.
Comets are icy balls of dust, and when they swing past the sun that frozen volatile material
turns into gasses that carry away the dust and give them that distinct tail as well as
a haze, or coma, around their nucleus.
Oumuamua didn’t have that, so scientists concluded it was an asteroid.
But recently, upon a closer examination, they noticed something odd.
Oumuamua had accelerated ever so slightly on its journey out of the solar system, more
than the Sun’s gravity could account for.
The only way they could explain it would be if it was jetting off material, but if it
was outgassing volatile material than that would make it more like a comet than an asteroid.
So it could be a comet.
But it’s long and tumbling, and if it were a ball of dust instead of a rocky and metallic
asteroid, some astronomers believe it’s should have torn itself apart.
It’d have to be something more solid, like, you guessed it, an asteroid.
But comets are more common and can be ejected from star systems much more easily than asteroids,
so for the first interstellar visitor to be an asteroid would be unlikely.
The debate probably won’t be settled any time soon.
Because of Oumuamua’s speed we only had a couple of weeks to observe it, and it didn’t
help that Hurricane Maria took Puerto Rico’s Arecibo Observatory out of commission.
All we can do is sit and wait for the next object like Oumuamua to come by and hope we’re
lucky enough to spot it.
In the meantime we’ll just pore over what we know and hope something definitive emerges,
or we’ll have to come up with something of an in between category to put Oumuamua
in.
I know some of you are sitting at home screaming that if it defies explanation, then it must
be extraterrestrial in origin.
Well we thought of that too.
Even though it was only observable for a couple of months, which left astronomers scrambling
for telescope time, SETI managed to scan it to see if it was emitting radio signals.
It was not.
Darn.
Trust us, no one wants to find signs of alien life more than astronomers, but as Dr. Meech,
an astronomer on the team that helped spot oumumua told us last year, "if you were gonna
say it's something extraordinary, you better have extraordinary proof.
" And as of now, we still don't have that proof.
So Oumuamua probably isn’t aliens, but that hasn’t stopped scientists from looking for
alien messages elsewhere, check out this video to learn more.
And fun fact, a new telescope set to start scanning the skies in 2021 is expected to
find as many as 10 new interstellar objects in a decade.
Don’t forget to subscribe, and I’ll catch you next time on Seeker.