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