How does this celestial body manage to wander around the edge of a black hole without being swallowed by it?

A black hole is an extremely powerful celestial body in the universe. Theoretically, the entity of a black hole is just a singularity with infinite density and infinitely small volume. However, since the area within the event horizon of a black hole is completely invisible, we may never be able to verify this inference.

Why is the event horizon of a black hole completely invisible? To get rid of the constraints of a gravitational field, you must have a certain initial speed. For example, to get rid of the constraints of the earth's gravity and enter low-Earth orbit, you must reach the first cosmic speed, which is 7.9 kilometers per second. To completely get rid of the earth's gravity and go to other planets, you must reach the second cosmic speed, which is 11.2 kilometers per second. If you want to get rid of the gravitational constraints of the entire solar system and go to deep space, you must reach the third cosmic speed, which is 16.7 kilometers per second.

The gravitational strength of a black hole is far beyond that of the earth and the sun, so within a certain range, even if the speed of light is reached, it is impossible to escape. Therefore, the area within this range becomes a completely invisible world, and the boundary of this invisible world is called the "event horizon".

Light cannot escape from the event horizon, but this does not mean that it is safe outside the event horizon. In fact, the range of influence of the black hole's gravity is very wide, but this is not surprising. Even the sun can act 2 light years away. Under the influence of the black hole's strong gravity, celestial bodies in a wide range will orbit around it, thus forming a more powerful gravitational core, which can dominate the operation of a galaxy.

Like all galaxies in the universe, the Milky Way has a stellar-mass black hole at its center, with a mass about 4 million times that of the sun.

This black hole named "Sagittarius A*" drives the dense celestial bodies around it to move and forms a gravitational core, which is the galactic center. Under the influence of the galactic center, the Milky Way with a radius of hundreds of thousands of light years begins to rotate. The celestial bodies around the black hole will orbit it due to the gravitational force of the black hole, but if the distance between a celestial body and the black hole is too close, it will undoubtedly be torn apart and swallowed by the gravity of the black hole. Are there any exceptions? Yes, in 2011, astronomers discovered such a celestial body. The spectral type of this celestial body is G, so it was named G2. When it was discovered, its trajectory was showing a trend of approaching the black hole.

At first, astronomers predicted that the ultimate fate of G2 would be to be torn apart and swallowed by the gravity of a black hole, so they waited with great anticipation. After all, it is not often seen to see a black hole swallowing a star. However, the result was surprising.

After three years of waiting, in 2014, G2 finally came to the closest place to the black hole's event horizon. Due to the strong gravitational pull of the black hole, its shape began to change and became longer and longer. However, it was not torn apart in the end, but escaped from the black hole. As the distance from the black hole increased, its elongated shape gradually returned to its original state. Astronomers did not wait for the spectacle of a black hole swallowing a star, but they waited for the grand sight of a star escaping from a black hole, which is even more rare. So what is G2's merit and ability, and why was it able to escape from the black hole's strong gravitational pull?

In fact, it is a bit far-fetched to say that G2 is a star. Strictly speaking, it should be a dust cloud. Through observation, we can only determine that its surface is a large amount of gas and dust.

But this dust cloud is different from ordinary dust clouds. It has a very high temperature. Where does the temperature come from? From this, we can infer that there is a star in the middle of the dust cloud. If so, why is there so much gas and dust attached to the outer edge of the star? Because this is not an independent star, but the product of the collision of two stars. Due to the collision, a large amount of gas and dust were released, so such a special dust cloud was formed. Of course, this is just speculation, and in response to this speculation, scientists from the University of Cologne in Germany put forward a different view.

Such a dust cloud does not necessarily contain a new star produced by the collision of two stars, but may also contain three stars orbiting each other, and the age of these three stars may be only about 1 million years.

Since the stars themselves are produced from the nebula, and these three stars have just been formed, there is still a lot of gas and dust around them that have not been absorbed. However, the only problem with this statement is that, based on current understanding, the conditions for star formation are not met near Sagittarius a*. Whether G2 is the product of the collision of two stars or three new stars, it cannot explain why it was able to escape from the edge of the black hole. In fact, humans have very limited knowledge of the extreme environment around black holes and the gravitational interactions between celestial bodies. This mystery still needs us to slowly solve.

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