More than two hundred years ago, the discoverer of Uranus William Herschel for the first time tried to draw a map of Milky Way through scientific means, but limited observation equipment limited his performance, and the drawing results were quite different from the Milky Way we have observed now.
At present, scientists generally believe that the Milky Way is a vortex galaxy, but this is just a rough drawing. In order to have a comprehensive understanding of the Milky Way, European Space Agency launched the Gaia satellite in 2013.
Through the data sent back by the Gaia satellite in recent years, scientists have discovered the changes in the Milky Way over the past billions of years and the collision events that will occur in the future. Recently, when scholars from Lund University in Sweden were sorting out Gaia's database, they found that the silver disk outside the Milky Way seemed to be disturbed by the gravitational disturbance of giant objects, and is "trembling", like ripples on the water .
Based on the relevant data provided by Gaia, researchers calculated the mass and flight trajectory of the giant object, believing that it may be a small galaxy located near Sagittarius: Sagittarius dwarf galaxy.
1994, astronomers discovered the Sagittarius dwarf galaxy 70,000 light years from Earth. It is only one-tenth of the size of the Milky Way, but it is very close to the Milky Way, so much like the satellite galaxy of the Milky Way, the Sagittarius dwarf galaxy has been constantly approaching the Milky Way for many years. Many scientists at at that time believed that it had probably been torn to pieces by the Milky Way galaxy. All we saw was the remains.
Later scientists discovered that the trajectory of the Sagittarius dwarf galaxy is still very regular. Its core looks loose, but it is actually still condensed together. This means that under the powerful tidal force of the core of the Milky Way, the Sagittarius dwarf galaxy still maintains its rough shape, but it is still in a slow disintegration process.
Even though its mass is far less than that of the Milky Way, it still causes tremors at the edge of the Milky Way. When observing stars on the galaxy, scientists found that the stars above have a tendency to move downward, and the stars below are also moving upward.
Scientists believe that this is the result of the Sagittarius dwarf galaxy repeatedly crossing the edge of the Milky Way. In fact, the second-generation data analysis of Gaia satellite shows that in the past 6 billion years, the Milky Way and Sagittarius dwarf galaxies have collided three times, one of which even indirectly gave birth to the solar system.
The latest collision occurred around 11 billion years ago, the second time was 2 billion years ago, and the first collision was 5 billion years ago, and this collision was closely related to the fate of humans and the solar system.
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If there is no external force, the polymerization of matter under gravitational disturbances, the solar system may appear many years later.
However, Sagittarius dwarf galaxy gave things a turn. Every collision will cause a lot of gas and dust inside it to peel off and enter the Milky Way. The substances of scattered everywhere and gradually stabilized as the collision ends. Finally, they aggregate together, forming a breeding ground that can nurture stars.
The time when the sun formed coincides with the time of the first collision. Although is hundreds of millions of light years apart, there may be some subtle relationship between them.
In several impacts, the Sagittarius dwarf galaxy was gradually swallowed by the Milky Way, and its mass was only about half of the initial mass. The rest were integrated into the Milky Way. The current Sagittarius dwarf galaxy and the Milky Way are increasingly blurred. Until one day in the future, the Sagittarius dwarf galaxy will completely coincide with the Milky Way.
Sagittarius dwarf galaxy approaches the Milky Way. There is a kind of tragic moths to the flames, but in fact, such galaxies merged is a common occurrence in the universe. As early as 8 to 10 billion years ago, a sausage galaxy called Gaia-Enclados also collided with the Milky Way . Its mass is much larger than that of the later Sagittarius dwarf galaxy, and it was eventually integrated with the Milky Way.
Most of the galaxies that collided with the Milky Way in the past were much smaller than the Milky Way. If the Milky Way collided with a galaxy that was comparable to it, what would happen to ?
Andromeda Galaxy is the closest large galaxy to the Milky Way, which contains trillions of stars. According to the observations of the Hubble Telescope , scientists estimate that in about 3.75 billion years, the two largest galaxies in the two galaxies will collide at a speed of 25,000 miles per hour and have a sustained impact over the next 40,000 years.
If humans were still living on the earth at that time, could see the phenomenon of stars in the sky being rammed?
The answer is no
When two galaxies collide, the chance of stars colliding is only slightly higher than 0. This is because the density of celestial bodies in the universe is not as large as we seem. , for example, the star closest to the sun is Proxima , the distance between them is 4.2 light-years , and 3440 solar systems can be placed in the middle.
Although you can't see the wonder of stars flying around, you can still see the spectacular scene of the fusion of the Milky Way and the Fairy System on Earth. The gorgeous Milky Way will no longer exist, and will be replaced by a more compact elliptical galaxy.
