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  • [♪ INTRO]

  • When you look up on a clear night,

  • virtually all of the stars you can see are part of the Milky Way.

  • Even the farthest one you can find without a telescope is less than 20,000 light-years from you.

  • That might seem really far away, and yeah it is, but space is way bigger than our little neighborhood.

  • It's so huge that it's hard to study the billions of stars outside the Milky Way.

  • In fact, the farthest star we've isolated is in a galaxy only 55 million light-years away.

  • At least, that's what used to be true.

  • According to a paper published this week in Nature Astronomy,

  • that record was blown out of the water.

  • Now, the most distant single star we've ever seen is 14 billion light-years from us!

  • Yeah, billion. With a B.

  • In general, it's not that uncommon for astronomers to observe faraway objects.

  • For example, with telescopes, they can see the brightest supernovas

  • up to 10 billion light-years away.

  • But individual stars are normally impossible to make out even a hundred times closer than that.

  • Unless they're gravitationally lensed.

  • This is what happens when a large amount of mass, like a galaxy, or an entire cluster

  • of galaxies, bends, distorts, and magnifies the light from objects behind them.

  • It's a phenomenon that happens because objects with a lot of mass

  • actually distort the space around them.

  • On average, galaxies experiencing gravitational lensing

  • get magnified about 50 times their 'normal' brightness.

  • But this new star, which was found behind a galaxy cluster

  • around six billion light-years away from here, got magnified 2000 times!

  • That star's name is officially MACS J1149 Lensed Star 1.

  • But the team that found it unofficially calls it Icarus.

  • Thank you, astronomers!

  • Scientists first found Icarus almost by accident, when they were studying images

  • of a supernova the Hubble Space Telescope took in 2016 and '17.

  • While studying the pictures, they noticed a second bright spot not too far away.

  • It was also varying in brightness over time, but not the way that supernovas do.

  • Specifically, the colors of light coming from it didn't change over the months of observation.

  • Further analysis of those colors revealed the object was a blue supergiant.

  • These are stars much larger, more massive,

  • hotter, and up to hundreds of thousands of times brighter than our Sun.

  • You know, just in case you needed another reminder that space is pretty hardcore.

  • All blue supergiants have similar profiles, so by comparing Icarus's light against stars in our galaxy,

  • the astronomers were able to calculate its distance.

  • They found that the light it's emitting is 9 billion years old,

  • and because the universe is expanding, that puts it about 14 billion light-years from us.

  • But how did Icarus manage to be magnified 2000 times,

  • when the regular amount from gravitational lensing is a measly 50?

  • The answer is microlenses, small objects within the larger lens,

  • like individual stars, that provide their own additional magnification.

  • Lenses within lenses.

  • That boost is only temporary,

  • because the microlenses will constantly be moving into and out of alignment.

  • But if the timing's right, the effect is massive.

  • Microlensing has even been used to find exoplanets outside the Milky Way!

  • Icarus isn't just a star for the record books, either.

  • By studying the pattern by which it gets magnified over time,

  • astronomers will be able to model exactly how matter is distributed in the lensing galaxy.

  • That includes its mysterious dark matter, which we can't see

  • but which has gravitational effects on other bodies.

  • So besides smashing records, Icarus probably has a lot more to teach us.

  • In other news announced this week, the Milky Way might begetting bigger.

  • At least that's what astronomers presented this week at the

  • European Week of Astronomy and Space Science in Liverpool.

  • Our galaxy has been around for a while,

  • and it's grown as new stars formed over millions and billions of years.

  • Previous work has shown that stars of different ages now exist in different parts of the galaxy.

  • For example, in the central bulge and galactic halo, there are lots of older stars,

  • because there isn't much raw material left there to make newer ones.

  • Meanwhile, in the outer edge of our galaxy's disk,

  • studies have identified star-forming regions where baby stars form all the time.

  • And general models for galactic evolution suggest that the new stars in these regions

  • will slowly cause the galaxy to grow.

  • If you think about, it makes sense.

  • It's like a city growing because people keep

  • building new neighborhoods on the outskirts of town.

  • Still, it's hard to actually study this happening in the Milky Way, 'cause

  • we're kinda stuck inside of it.

  • To get around that, a team of astronomers studied two other galaxies

  • that might have similar spiral structures to ours.

  • If these galaxies seem to be getting bigger from star formation at their outer edge,

  • then it's not unreasonable to infer that the Milky Way is, too.

  • By collecting optical, ultraviolet, and infrared data of young, blue stars in these galaxies'

  • outer disks, scientists were able to calculate their vertical movement,

  • how much they were moving up and down compared to the disk.

  • Then, they could convert that into a galactic growth rate.

  • These stars appeared to have velocities of about 500 meters per second,

  • so the Milky Way could be growing at that same rate.

  • That seems pretty fast, but it's really not too speedy on a galactic scale.

  • In about 3 billion years, it means our neighborhood would only have grown by 5%.

  • Then again, that growth rate might be completely messed up by then,

  • because our galaxy will collide with Andromeda in about 4 billion years.

  • But hey, no matter what happens, studying how galaxies grow

  • still helps us better understand the universe.

  • Because even though the Milky Way is our home,

  • there's a whole lot we don't totally understand about our corner of space.

  • But that doesn't mean that there's not a ton to celebrate about our corner of space!

  • We recently restocked SciShow Finds, which is a site

  • filled with objects that we curated from this lovely planet of ours.

  • So if you need the most powerful refrigerator magnets in existence, or a science lab you

  • can carry around in your pocket, or just a reminder that honeybees are really great,

  • you can go to scishowfinds.com, and if you ever order something from there for yourself,

  • or as a present for someone that you like,

  • just know that you're supporting SciShow when you do it.

  • [♪ OUTRO]

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