[ ♪ Intro ♪ ]
After years of searching, there's one place in the solar system where we've managed
to find life.
Okay, so I'm talking about Earth.
But there are other bodies that astronomers suspect could be habitable -- at least for
special types of single-celled life forms.
Probably not, like, space hippos or anything.
Although that would be awesome.
One of those bodies is Saturn's moon Enceladus, which almost definitely has an ocean's worth
of liquid water underneath its icy surface.
Based on what we know about life, we've thought this environment could be habitable,
but we haven't known that for sure.
But now, we do.
According to research published on Tuesday in Nature Communications, Enceladus' environment
could totally be habitable for at least one real-world microbe.
We don't know the exact conditions in Enceladus' oceans, but astronomers do have some educated guesses.
Plumes of water actually shoot into space through cracks at the moon's southern pole,
and we've driven the Cassini spacecraft through some of them to figure out what compounds
were inside.
Besides regular old H2O, there were molecules like carbon dioxide, hydrogen, ammonia, and methane.
That last one's especially important, because methane is produced by all kinds of organisms
on Earth, including single-celled archaea.
So this could be an indicator that there's life on Enceladus, too.
But before scientists got ahead of themselves, they had to see if methane-producing organisms
could even survive there.
That's where this new paper came in.
In this study, a team of researchers got together three different, methane-producing species of archaea.
Then they cultivated them in an environment we think is similar to Enceladus' southern ocean.
Specifically, they looked at the composition of gases, the pressure, and the pH.
Some of the gases on Enceladus -- like ammonia -- actually prevent certain species of archaea
from growing.
So they wanted to see if any of these three could not just survive, but thrive.
And one did.
It's a little microbe known as Methanothermococcus okinawensis, which is a mouthful.
It came from a hydrothermal vent field almost a thousand meters below sea level in the East China Sea.
Of course, just because one species could thrive in the lab doesn't mean there are
definitely microbes swimming on another world.
The researchers caution that methane can also be created through chemical reactions that
don't require living organisms.
And even if there is life making methane on Enceladus, geologic processes are definitely
responsible for at least some of it, too.
Still, the fact that we've found one species that could theoretically live there suggests
there could also be others.
And that strengthens astrobiologists' hope for finding life beyond the rock we call home.
Meanwhile, on pretty much the other side of the observable universe, a star went supernova.
Well, it actually went supernova about 10 and a half billion years ago.
But since light can only travel so fast, we had to wait a while to see it.
The good news is, it was totally worth the wait.
Thanks to a study published last month in The Astrophysical Journal, we've confirmed
this supernova is officially the oldest one ever detected.
The cosmic explosion -- memorably dubbed DES16C2nm -- was first captured in 2016 by the Dark Energy Survey.
The DES is an international collaboration trying to pin down the science behind dark energy.
That's the mysterious phenomenon astronomers believe could be causing the universe's
expansion to accelerate.
To investigate it, the survey is mapping 300 million galaxies, all billions of light-years away.
It isn't specifically looking for supernovas, but when you study that many galaxies, you're
bound to find one or two.
This one just turned out to be a special bonus -- and not only because of its age.
DES16C2nm actually belongs to the rarest class of supernova, known as superluminous supernovas.
And as the name implies, they're really bright -- about 100 times brighter than your
typical supernova, and even brighter than some galaxies!
They were discovered about a decade ago, and since then, we've only managed to identify
a handful of them.
We're still trying to pin down exactly how they work, but some scientists think they're
caused by matter falling onto a newly-formed magnetar.
Magnetars are the rapidly spinning, super dense cores of massive stars that went supernova,
and they have a magnetic field 100 trillion times stronger than Earth's.
And that makes them emit a lot of energy.
As that energy interacts with matter falling onto the magnetar, it makes the supernova extra bright.
Now that they've spotted one superluminous supernova, astronomers can go back into the
DES data to see if they can find more.
And future projects, like NASA's Wide-field Infrared Survey Telescope, will also be able
to detect ones even more distant.
It'll be able to find supernovas from when the universe was less than a billion years old!
And this is important because, the more distant superluminous supernovas we can find, the
more we can understand how space evolved.
Information on these supernovas is few and far between, but as far as we can tell, they
seem to explode in more or less the same way -- at least within a specific range of wavelengths.
If this is true, we could use these supernovas as distance markers to figure out how far
it is to different galaxies, and to figure out the size and even age of the universe.
With more research, they could possibly help us answer some of the many questions surrounding
the expansion of the universe -- or even dark energy itself.
Thanks for watching this episode of SciShow Space, which we couldn't make without our
Patreon supporters.
A year ago this coming Tuesday, we launched another project that couldn't exist without
our patrons: SciShow Psych.
As a thank-you to our patrons who made that channel happen, we'll be having a birthday
livestream celebration for SciShow Psych on Tuesday, March 6 at 3pm ET.
Hank and Brit will be there, as well as some of the crew, and if you're a SciShow patron,
we hope you can join us for this hour-long livestream too!
Bring your psych questions and your party hats!
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