The state of our knowledge about the Universe
is in a strange place now. We can map countless stars around us, but
we seem to be just stumbling upon every discovery. Some of them are so puzzling, even skeptical
scientists start to suspect aliens! The brightest example is the Tabby Star, who’s
light dims as if there was a giant artificial megastructure around it. But what’s really happening there? KIC 8462852, or simply called Tabby Star,
is a mysterious celestial object situated in the constellation Cygnus, some 1,470 light-years
away from the Sun. Nothing about this star is particularly exceptional. It’s about 50% bigger than our Sun, and
1,000 degrees hotter, and there are other objects just like it in the Universe. Nevertheless, it became known as the strangest
star ever observed. To understand why, we should dive a bit deeper
into how it was first found. Astronomers have developed several methods
of detecting and researching stars throughout the recent decades of rapid technological
progress, but one of them stood out. It wasn’t only suitable for star discovery,
but also allowed the detection of some of our greatest points of interest to date. Exoplanets. Outer worlds, orbiting distant stars. They’re hiding the keys to all the mysteries
about our solar system, and any possible answers to the sacred questions we’re still afraid
to ask: how did we come to be, and is there any other life in the Universe? This method is called transit photometry. Don’t mind the big name; to simplify it
to its core, this method can be explained with a trivial example. Imagine you’re looking at some distant light,
and then something flies right in front of it. The light is too bright and the object is
too far and fast for you to even guess if it was a bird or a bat, but you can tell for
sure that something was there a second before. That’s because the light itself dimmed and
flickered for a moment. You can even figure out how big that object
that passed by was, by how long and strong the observed dimming was. Transit photometry measures the dimming of
the star’s light when the planet passes on its orbit between the point of observation
and the star in question. As you can already see, this method provides
a lot of information, but has its flaws. This is exactly the reason why so much guesswork
is involved when using transit photometry. Despite that though, a record number of exoplanets
were discovered using it in 2014 – around 850 planets total! Tabby Star is named after Professor Tabetha
Boyajian, who was the first to notice a strange quality: while other stars dim by about 1%
when a planet passes in front of them, Tabby Star dimmed much more. The first recorded sightings of it, made in
1890, testify that by the year 1989, this star had lost about 20% of its shine. Of course, this couldn’t be caused by a
planet passing by. Let’s just say it would take a planet bigger
than the star itself to do that, but that’s just impossible. Stars remain the same brightness for billions
of years with almost no change at all. It became even more strange when astronomers
figured out that Tabby Star is in the middle of its life-cycle. There shouldn’t be any disturbances in its
light whatsoever. But what caused the dim then? This is where the notorious guesswork began. Or should I say, a long scientific investigation. In 2016, Boyajian and her team found archive
recordings suggesting that Tabby Star isn’t just fading rapidly. At times, its shine is restored to its natural
state, and then it gets obscured once again. They were even able to figure out a pattern
of dims, reliably predicting the next shift in brightness. This produced the first theory – Tabby Star
may have a giant hive of comets and asteroids orbiting around it. It could obscure the light of the star in
the places where the group of objects is denser. But that theory fell short. Hives like that are observed only around young
stars going through the process of their formation, and Tabby is much older than that. Besides, a high number of comets around the
star would produce a titanic amount of infrared radiation, but it wasn’t ever detected. And then consider the following: the shifts
of brightness are identical each time; some of them even go in a symmetrical shape. Can you imagine a hive of comets that goes
in a strict order with each spin around the blazing star? That’s unheard of; they would change their
position constantly. Their movement would appear almost chaotic
to any observer on the Earth. Looks like lots of comets, but goes in strict
patterns? Yeah, you’re not the only one who thought
that it sounds like something unnatural. In fact, the idea of a structure spinning
around a star is long known to astronomers. It’s called the Dyson Sphere. Hypothetically, a structure like this could
be made by a highly developed civilization to harvest the energy from a star. It would consist of a high number of thin
plates positioned around a star – you can imagine them like moon-sized solar panels. The most interesting thing about this idea
is that such structures would be relatively easy to find, because they would obscure the
stars in a strange and inexplicable way. Dyson Spheres are proposed to be the first
sign of a highly advanced civilization existing in the Universe. The probability of a Dyson Sphere causing
Tabby Star’s dimming was put to the test by searching for any radio signals in the
area of the star, but unfortunately, scientists were met with nothing but silence. There’s a catch though. Our data can be unreliable if we’re really
talking about some other civilization. If they’re able to build something like
the Dyson sphere, they might not use radio signals at all. It’s unimaginable for us here and now, but
in a somewhat distant future, we too may refuse to use the radio as a prime way of communication. Just some 300 years ago, we could only use
the postal service to communicate with each other from a distance. On a galactic scale, 300 years is just the
blink of an eye! Imagine how wondrous some new or completely
alien technology could be! Anyways, the scientific community was, shall
we say, outraged about the decision to even try and test the alien theory of Tabby Star’s
mystery in the first place. From a skeptic’s point of view, it’s always
better to rule out every other natural possibility, and only then consider something un-natural
like that. So recently, another, much more grounded,
Tabby Star theory emerged. According to it, there must be a giant brown
dwarf planet going around Tabby Star at distant orbits. And I mean giant. Brown dwarfs are barely considered planets
at all. They are objects much more massive than the
biggest of Jupiter-like planets, but smaller than the tiniest red dwarf star – the lightest
type of star there is. The presence of several brown dwarfs in orbit
around one star is quite unlikely by itself, but that’s not even everything that would
have to be involved to result in something like the mysterious Tabby Star dimming. These brown dwarfs should have colossal asteroid
rings. And once again, I can’t stress the word
‘colossal’ enough – these rings should be far beyond the limit that we’re aware
of currently. This limit has a name – Roche radius. Beyond this radius, no asteroid ring can sustain
its form; it’ll eventually all collect into one object and become a satellite. The particular brown dwarf that’s theoretically
orbiting Tabby Star would have to be 15 times more massive than Jupiter, and have 6 layers
of planetary rings. It still doesn’t sound too reliable, but
that’s the best theory there is. Or, to be fair, the best there was until last
year. Astronomer Brian Metzger and his colleagues
at Columbia University suggested that the objects surrounding Tabby Star and causing
the strange flickering of its light might be the remains of crushed planets and their
exomoons. Their theory implies that those planets could’ve
crossed the same old Roche radius of the star itself. When that happens, the planets would deform,
pull, and flatten; then they break into pieces under the colossal influence of Tabby Star’s
gravitational force. Even though this should’ve happened around
200,000 years ago with Tabby Star and its planet, the remains of this object would still
be in a close orbit of the star. That’s what obscures Tabby Star from our
telescopes from time to time. Can this theory place a period in the long
investigation of Tabby Star’s mystery? It’ll eventually be proven either true or
false. Until then, Tabby Star will remain the greatest
secret of the stars. Now, have you heard of some strange celestial
objects or phenomenon that caught your attention more than this one? Let me know down in the comments! If you learned something new today, then give
this video a like and share it with a friend. But – hey! – don’t go naming your cat
Tabby Star just yet! We have over 2,000 cool videos for you to
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