Earth in danger from ‘monstrous’ black hole at the center of the Milky Way?

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A gigantic work, which involved hundreds of scientists, five years of investigations and telescopes spread across eight different places on the planet was able to capture the first images of Sagittarius A*, a black hole located at the center of the Milky Way, the galaxy in which finds our Solar System.

The discovery, released on May 12, raised a pertinent question in the minds of many people: could this black hole, a structure that “sucks up” everything close to it, pose some kind of danger to planet Earth?

The answer is no, but with one caveat. Scientists who were part of the international effort explained that Sagittarius A* is far enough away from us (26,000 light-years to be exact) to pose a future threat.

On the other hand, it is not ruled out that our galaxy will merge or “collide” with another in a few billion years, which could dangerously bring Earth closer to a black hole. It is worth noting that this is a very unlikely scenario — and one about which we would have many warnings and warnings before something bad of this magnitude becomes reality.

Throughout this article, you will understand the importance of recent findings about Sagittarius A* and why the risk of planet Earth being “sucked in” by a black hole is a remote possibility, according to what scientists know so far. .

In the heart of the Milky Way

Sagittarius A*, also known by the acronym SgrA*, is a gigantic black hole that lives at the center of our galaxy, the Milky Way.

The object is a staggering four million times the mass of the Sun and was pictured for the first time thanks to a collaborative effort of hundreds of scientists, brought together on the project. Event Horizon Telescope (EHT).

In the image released by the group, it is possible to see a dark central region where the black hole resides, surrounded by a ring of light from superheated gas accelerated by immense gravitational forces.

To give you an idea, this ring is roughly the size of Mercury’s orbit around our star, the Sun. This represents about 60 million kilometers in diameter.

Fortunately, this “monster” is far, far away — about 26,000 light-years away.

This is the second such image to be released by the EHT. In 2019, the group shared an image of a giant black hole that is at the heart of another galaxy, called Messier 87, or M87. This structure is more than a thousand times larger than SgrA*, with 6.5 billion times the mass of the Sun.

“But the new image of SgrA* is special because it is our supermassive black hole,” says Professor Heino Falcke, one of the pioneers behind the EHT project, to BBC News.

“This black hole is in ‘our backyard’, and if you want to understand how these structures work, SgrA* will tell you, because we can visualize it in detail”, adds the German-Dutch scientist, who works at the University Radboud in the Netherlands.

What is a black hole?

  • A black hole is a region of space where matter has collapsed in on itself.
  • The gravitational pull there is so strong that nothing, not even light, can escape.
  • Black holes often arise from the explosive death of large stars
  • Some are really huge and have billions of times the mass of the Sun
  • Science still doesn’t know how these monstrous structures — commonly found in the centers of galaxies — formed or what happens inside.

Image of Sagittarius A* deciphered


How was the photo taken?

At a distance of 26,000 light-years from Earth, Sgr A* is a pin in the sky’s great haystack. To discern a target at this distance, it takes incredible resolving power from the equipment.

The EHT “trick” is to use a technique called very long baseline matrix interferometry (VLBI).

In short, it combines a network of eight radio antennas spread across various parts of the world to “mimic” what a planet-sized telescope would look like.

This arrangement allows the EHT to cut an angle in the sky that is measured by a parameter known as microarcseconds. EHT team members explain that this allows for clarity of vision similar to being able to see “a donut on the surface of the Moon”.

In addition, scientists have also turned to atomic clocks, smart algorithms, and countless hours of supercomputing to build a multi-petabyte (1 petabyte equals one million gigabytes) image from the collected data.

The way a black hole “bends” light means there is nothing to see but a “shadow”, but the glow of matter orbiting around that darkness reveals where the object is located.

Is it possible to compare the current image, from SgrA*, with the previous one, located in the galaxy M87? Experts point out some fundamental differences.

“Because Sagittarius A* is a much smaller black hole — it’s about 1,000 times smaller than M87 — its ring structure changes over 1,000 times faster timescales,” explains astronomer Ziri Younsi of University College London. , in the United Kingdom, which is part of the EHT.

“This process is very dynamic. The dots you see on the ring move day by day.”

These rapid changes in the vicinity of Sgr A* are part of the reason why it took much longer to produce an image of it than it did of the black hole in the galaxy M87, despite the fact that it is much further away from us. Interpreting the data has been a more difficult challenge.

Telescope observations for the two black holes were acquired during the same period in early 2017, but M87, which is larger and 55 million light-years away, appears static compared to the Milky Way’s central black hole.

Does the black hole pose any danger to Earth?

In an interview with BBC News broadcast on British television on 12 May, astrophysicist Gibwa Musoke, from the University of Amsterdam, answered the question of whether SgrA* is a threat (or not) to our planet.

“No, the black hole does not pose any danger to us. It is really far from Earth”, explained the expert.

But if black holes are like giant vacuum cleaners and there are millions of them in the galaxy where Earth is, could our planet be sucked into this kind of celestial body that still holds many mysteries?

“The short answer is yes, it could happen. But it is very unlikely, and we would have some warnings before something really bad becomes a reality,” wrote astronomer Christopher Springob on the Cornell University website (USA), about the possibility of a hole approaching. and swallow our planet.

Despite the thousands of light-years that separate Earth from the nearest black hole, the scientist believes that it cannot be 100% ruled out that a supermassive black hole will approach us if our galaxy merges or “collides” with another.

Although considered an unlikely hypothesis, “Earth could be launched at the center of the galaxy, close enough to the supermassive black hole,” said Yale University astrophysicist Fabio Pacucci in a TED talk.

That’s because, according to the expert, “there will be a collision between the Milky Way and the Andromeda galaxy within 4 billion years, which may not be good news for our planet.”

And if that does happen, what could happen to Earthlings?

Most likely, all the inhabitants of the planet will die violently. Either fried, with the heat of the collision, or made into “spaghetti” (or maybe, both options at once).

“If you’re too close to a black hole, it’s going to stretch, just like spaghetti,” Kevin Pimbblet, a professor of physics at the University of Hull in the UK, wrote in the publication. The Conversation.

“This effect is caused by a gradient of gravitation that passes through your body”, explains the professor, further saying that different parts of our body would experience different degrees of this force.

“The result is not just a lengthening of the body in general, but also a compression in the middle. So your body or any other object, like the Earth, would start looking like spaghetti long before it gets to the center of the black hole,” notes Pimbblet. .

This would cause the parts closest to Earth to stretch out while the other parts are compressed by different gravitation. The result would be catastrophic.

What’s inside black holes?

Inside black holes is everything that went into them. The problem is that you don’t know what state things are in there.

But if it were possible to reach and enter one of these holes, what would we see? There are different theories. “One of the possibilities is ‘the wall of fire’ which, as the name suggests, is a bunch of flaming particles that would fry you like a potato,” answers astronomer Andrew Pontzen, who studies the origin and evolution of the universe. .

About shape, we know that black holes are spherical bodies. And if it were spinning — which is quite likely, since all objects in the universe rotate to some degree — the hole would be wider at the center, rather than being a perfect circle.

The force of gravity attracts gas and dust that accumulate in a spiral. As the material is consumed, friction heats it to billions of degrees, producing massive amounts of radiation and leaking energy and charged particles.

While many of the mysteries about black holes remain, work like the team that makes up the EHT, which managed to capture the first images of these massive structures at the heart of galaxies, brings us closer to possible answers.

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