Space. It’s full of mysteries that have
remained unsolved for centuries. But recently, the cosmos has surpassed itself by baffling
the world with a new, scary abnormality. Apparently, something is tearing holes in the Milky Way,
the galaxy that contains our Solar System! Scientists have several theories, but none
of them sound particularly reassuring. When astronomers started the Gaia observations,
a project that was organized to create a detailed 3D map of our galaxy, they didn’t expect to
find anything surprising. But that’s exactly what happened. Earlier this year, Harvard
scientist Dr. Ana Bonaca noticed a weird disturbance in our galaxy’s stellar streams. A stellar
stream is a line of stars that are moving together through galaxies. The stellar stream
we’re talking about is called GD-1, and it’s stretched in an impressive line across our
sky. Anyway, this stream used to be a cohesive
line, stretched by the gravity of our galaxy. Well, not anymore! One day, Dr. Bonaca noticed
a gap in the stream, and this gap had a strange ragged edge. In fact, it looked like something
terrifyingly huge recently plunged through the stellar stream; and the sheer force of
this object’s gravity was so great that it managed to drag stars in its wake. The most
shocking thing was that the telescopes simply failed to find the source of the damage. But
then, what could this unseen bullet be? One theory suggests that the intruder is a
stray star. However, the hole is too enormous for this idea to sound plausible. According
to Dr. Bonaca, the hole is way bigger than any existing star. It’d have to be a million
times more massive than our Sun! That’s why this theory can be ruled out.
But what if the hole in the Milky Way was torn by a supermassive black hole like the
one that dwells in the center of our galaxy? If it was, it’d be a pretty scary scenario.
If these two black holes got too close, they wouldn’t be able to escape each other’s gravity,
and a collision might be inevitable. And it would be an extremely violent event. The stronger
of the two holes would consume the weaker one, and one huge, super mighty black hole
would appear. But, people have yet to witness a collision
of black holes. What’s more, scientists can’t predict the consequences of such a merge,
even though they’ve simulated it on powerful computers. The only obvious fact is that it
would produce incredible amounts of energy and send huge ripples through the Universe.
Naturally, these ripples would be bound to eventually hit our planet.
On the other hand, two black holes in one galaxy might refuse to merge. Imagine this:
a supermassive black hole hundreds of millions of times the mass of the Sun is spinning in
the center of the Milky Way at a phenomenal speed. Another spinning black hole approaches
“ours.” What do you think will happen? Right, one of the holes, most likely the intruder,
will get kicked out and sent hurtling away like a Frisbee flying through space. And who
can guarantee that it wouldn’t head toward the Earth?
Luckily for us, there aren’t any supermassive black holes in the vicinity, so this theory
fails to explain the mysterious bullet-hole phenomenon.
Naturally, astronomers have continued their observations. But what baffles them is that
there’s no large object made from ordinary, light-reflecting matter moving away from the
bullet-hole. This fact hints that the culprit that tore our Milky Way could be… dark matter?!
Dark matter is mystifying and invisible, and it makes up more than 27 percent of all the
matter in the Universe. For comparison, the regular matter, which is virtually all the
stuff we can see, makes up only a mere 5 percent of the Universe. And the rest is dark energy,
which is a bizarre phenomenon, still unclear to researchers but associated with the never-ending
expansion of the Universe. But back to our dark matter, which gets even
more confusing once you learn about the following paradox. On one hand, scientists have never
directly detected dark matter, despite conducting tons of experiments. On the other hand, after
observing dark matter’s gravitational pull, astronomers are sure that this substance does
exist. They came to the conclusion that dark matter doesn’t move around much, and neither
produces nor interacts with light. Well, no wonder it’s called dark!
So, what if it WAS dark matter that harmed our galaxy, and what if it reached Earth?
Unlike a stream of regular matter, dark matter wouldn’t see the Earth as an obstacle. It
would just pass through. But that’s not the most amazing part!
The thing is that after the dark matter passes through the planet’s core, the Earth’s gravitation
would most likely bend the stream into dense, thin hairs! These hairs would have “roots”
and “tips,” just like human hairs do. In the “root” of a dark matter hair, the particle
density would be a billion times higher than average! Also, the root would be somewhere
around 600,000 miles away from the Earth’s surface, or, in other words, two times further
than the Moon. As for the “tip” of the hair, it would be even further from Earth. How would
it influence our planet and us? Well, it’s still unclear, but the chances are that people
wouldn’t even notice the dark matter intrusion. (Until too late. Nah, just kidding.)
At the same time, if it were indeed a dense ball of dark matter that had damaged the Milky
Way, scientists would be more than happy! This would provide them with the perfect opportunity
to study the elusive substance. On top of that, it would prove the theory that dark
matter is lumpy rather than smooth or evenly distributed all over the Universe.
However, Dr. Bonaca still doesn’t rule out the possibility that the intruder is a luminous
object that, after tearing a hole in the Milky Way, is hiding somewhere in the galaxy. But
again, it seems highly unlikely because of the huge size of the object: according to
scientific estimation, it would be 30 to 65 light years across!
In any case, it’s hard to predict where it would’ve ended up if it were a luminous
object, and here’s the reason. The intruder could’ve been moving at an incredibly high
speed, and wouldn’t have to be very massive to tear a hole in the stellar stream. Or,
it could’ve been moving more slowly but be very heavy. But the astronomers don’t know
which option it was, that’s why it’s next to impossible to predict where it ended up. Well, it seems that for now, our intruder
remains a mystery that will torture the minds of astronomers from all over the world. As
if the galaxy isn’t already a bizarre and often illogical place! Just have a look at
its outskirts: they’re protected by a halo of hot gas, studded with dying stars and beautiful
globular clusters. The latter are spherical groups of stars that are tightly bound by
gravity and orbit the galactic core as satellites. But that’s not all! The edge of the galaxy
can even contain traces of a “ghost” galaxy – one that’s older than our Milky Way!
Curiously, the astronomers who discovered the “ghost” galaxy, which is a satellite galaxy
of the Milky Way, can’t explain its origin and nature. Named Ant 2, the galaxy was dubbed
“ghost” because it’s weirdly dim. Besides, for a dwarf galaxy – yep, those do exist!
– Ant 2 is too large, too faint, and doesn’t have enough mass for its size. A walking paradox!
However, scientists have an idea why the “ghost” galaxy might be so abnormal. The thing is
that the Milky Way could be constantly tearing chunks of this satellite galaxy with its gravitational
field. It would explain the dimness of the galaxy and its low mass. But then, it doesn’t
clear up why Ant 2 is so big. Usually satellite galaxies shrink, not grow, when they lose
their mass to the Milky Way’s gravitational pull. The “ghost” galaxy’s unexplained quirks
made astronomers call Ant 2 an oddball and add it to the list of space mysteries and
paradoxes. Okay, my brain exploded with that oner. Have you heard about any other mysteries space
has in store for us? Let me know down in the comments! If you learned something new today,
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