00:00Most of those twinkling dots scattered across the night sky seem unreachable.
00:06But one of them is Betelgeuse, a star so enormous and nearby that you can see it with the naked eye.
00:14To find it, locate the first three big dots in the Orion's belt.
00:20A reddish star to the left is Betelgeuse.
00:23It's one of the brightest stars we can see from Earth.
00:25And it's just 640 light-years away. No big deal.
00:30Betelgeuse has a blue-white O-type star, which is one of the hottest types to exist.
00:37Betelgeuse was scorching hot, reaching temperatures of about 90,000 degrees Fahrenheit.
00:43Although that was back in the day, now it's an elderly star and it cooled down to just 5,800 degrees.
00:50You know, vacation weather.
00:52Blue-white stars are absolutely massive and burn incredibly bright because they have loads of hydrogen fuel.
01:01But they have a price to pay for this glory.
01:05They burn through their fuel super quickly.
01:07As they age, they transform into red giants.
01:11This is exactly what happened to Betelgeuse.
01:14It burned through its hydrogen and started burning helium instead.
01:17This caused its outer layers to puff up like a balloon, turning it into a red supergiant and making it one of the largest stars out there.
01:28Now it's stretching over 700 million miles in diameter.
01:32Now it's about a thousand times bigger than our sun.
01:37If Betelgeuse replaced it, it would swallow up Mercury, Venus, Earth, Mars, even Jupiter.
01:44And its atmosphere would almost reach Saturn.
01:46But something strange has been going on.
01:50Betelgeuse spinning way faster than it should for a star of its size.
01:55Huge stars like Betelgeuse are expected to rotate slowly.
01:59But it suddenly started spinning at a rate of about 3 miles per second.
02:04Thanks to powerful radio telescopes, Betelgeuse's orange-red surface can be seen in detail.
02:11That's how we learned that it often changes its brightness.
02:14Sometimes, Betelgeuse shines super brightly and then gets very dim.
02:21This happens about every 400 days.
02:25And recently, a telescope called ALMA, which is made up of many antennas working together as one,
02:31showed that Betelgeuse's surface seems to be moving unevenly.
02:35It's like one side is coming towards us while the other is moving away.
02:40But all of it might be a trick of light.
02:43Betelgeuse isn't as smooth as our sun.
02:46Instead, it's super chunky.
02:48Its surface is like a boiling cauldron.
02:51It's bubbling and churning incredibly fiercely.
02:54Imagine giant plumes of hot gas erupting from its core,
02:59reaching the surface and then vanishing back inside.
03:02And these bubbles are bigger not only than the sun, but Earth's entire orbit around the sun.
03:09These bubbles also rise and fall super quickly, even faster than a spacecraft.
03:15And maybe this tricks our telescopes into seeing it spin faster than it really does.
03:20Some astronomers also think that Betelgeuse could have swallowed up another star.
03:25And this gave it a spin boost.
03:28But these are all just theories.
03:31Things got even more complicated when Betelgeuse dimmed once again,
03:35this time in a pretty unexpected way.
03:37What's interesting, it was discovered using a weather satellite.
03:42A regular telescope had a hard time seeing Betelgeuse clearly because of Earth's atmosphere.
03:48So they used a satellite that normally watches Earth's weather,
03:51but can also take pictures of space.
03:53As we mentioned, it usually brightens and dims about every 400 days.
04:00But recently, it suddenly dimmed by 2.5 times more than ever before.
04:05This event got the name, the Great Dimming.
04:10The first theory said that Betelgeuse cooled down and sneezed out a bunch of material,
04:15creating a massive dust cloud.
04:18This cloud blocked the view of the star, making it look much fainter than usual.
04:22They also noticed something strange happening to that dust.
04:26It started behaving differently,
04:28which might be a sign that something deep inside the star was causing trouble.
04:33Betelgeuse's brightening and dimming cycle now happens faster in just 200 days instead of 400.
04:40And to add to the mystery, in the spring of 2023,
04:43it started shining even brighter than it normally does at its peak.
04:48Why is this frightening?
04:49Because Betelgeuse might be preparing for its grand finale.
04:53And this wouldn't be very good for Earth.
04:56We might be on the verge of a supernova.
05:00When massive stars like Betelgeuse run out of fuel in their cores,
05:04they start burning different elements like carbon, oxygen, and silicon.
05:09Eventually, they end up with iron in their cores.
05:12At that moment, everything changes.
05:14Adding helium to iron doesn't produce energy like other reactions do.
05:20Instead, it sucks up energy.
05:22This causes the star's core to collapse,
05:25leading to what's called a core collapse supernova.
05:28A spectacular, breathtaking show.
05:32Supernovas are so bright that they can outshine entire galaxies.
05:36But a Betelgeuse supernova would be special.
05:40Because it's relatively close to us,
05:41it would be so bright that we could see it even during the day.
05:45When it happens, Betelgeuse will shine as brightly as a full moon.
05:50But all that light will be concentrated in one point.
05:54For about two months,
05:55it will be so bright that you could read a book just from the light of the supernova,
05:59even if you turned off all the city lights and had a clear sky.
06:02The idea of witnessing Betelgeuse explode as a supernova is truly thrilling.
06:09After all, the last time a star went supernova in our galaxy
06:13was way back in the time of Johannes Kepler,
06:16more than four centuries ago.
06:18That event, known as the SN1604 or Kepler supernova,
06:23dazzled the sky for weeks.
06:25But don't get too excited yet.
06:28We're not sure when exactly it'll happen.
06:31One study says that the star might be in its carbon-burning phase.
06:36If we're near the end of that stage,
06:38then Betelgeuse might blow up very soon,
06:41during the next tens of years.
06:43But it's nearly impossible to determine,
06:46because during that last phase,
06:48the star barely changes at all.
06:51Even though Betelgeuse is close enough for us to study its surface,
06:54we can't peek inside its core to see what's really happening with it.
06:58We might as well be at the beginning of the carbon-burning phase,
07:03and in that case,
07:04we might have to wait a thousand more years before that cool supernova.
07:09Another study says that Betelgeuse might have less than 300 years of fuel left in its core.
07:15They say that Betelgeuse is known to expand and contract regularly,
07:20and its pulsation pattern hints that Betelgeuse is much larger than we previously thought.
07:26This would suggest that the star is further along in its life cycle,
07:30and closer to going supernova.
07:32Other guesses come from observations of similar stars.
07:37For example,
07:38a star called VYCMA in our galaxy
07:41is thought to be closer to going supernova than Betelgeuse,
07:45and it's been dimming steadily over the past century,
07:48unlike the relatively stable Betelgeuse.
07:52If Betelgeuse was about to go supernova,
07:54it would dim steadily and very quickly.
07:58Also, historical records suggest that about 2,000 years ago,
08:01people saw Betelgeuse as yellow, not red.
08:05If that's the case,
08:06then we might be in its early last days after all.
08:09In other words,
08:10we have no idea whether it will go supernova tomorrow,
08:13or in a thousand years.
08:15We just gotta wait and see.
08:18But let's say it goes supernova tomorrow.
08:21What happens to us then?
08:23The 1987 supernova in the Large Magellanic Cloud
08:27showed that the effects from the supernova
08:30might be so strong,
08:32we can sense it even from very far distances.
08:35The Large Magellanic Cloud
08:37is almost 170,000 light-years away,
08:40and we still detected the radiation.
08:43It's kinda hard to say exactly what the danger zone is.
08:47A rough estimate could be around 100 light-years.
08:51Luckily, Betelgeuse won't pose any danger to humans.
08:54It's hundreds of light-years away,
08:56and it's supernova won't influence us in any way.
09:00We'll be able to enjoy it's supernova beauty
09:02without any harm.
09:07That's it for today.
09:08So hey, if you pacified your curiosity,
09:10then give the video a like
09:12and share it with your friends.
09:13Or if you want more,
09:14just click on these videos
09:15and stay on the Bright Side.
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