Four billion years later, the Milky Way will be hit by Andromeda, and there will be a big bang. What should humans do?

The Milky Way is a oblate sphere with a huge disk structure, consisting of a bright and dense core, two main spiral arms and two unformed spiral arms, which are 4,500 light years apart. The sun is located on the arm of Orion, an arm of the Milky Way, and the distance to the galactic center is about 26,000 light years.

The center of the Milky Way is a complex and dense radio source Sagittarius A, and its position near the center contains a supermassive black hole (Sagittarius A*), which is considered as the central black hole of the Milky Way and the supermassive black hole closest to the solar system [3]. The Milky Way consists of a silver heart, a galaxy, a silver disk, a silver halo and a silver crown from the inside out. Most of the central regions of the Milky Way are old stars (mainly white dwarfs [4]), and most of the peripheral regions are new young stars. There are more than a dozen satellite galaxies around hundreds of thousands of light years, of which large magellanic cloud and small magellanic cloud are the largest. The Milky Way keeps growing by slowly devouring dwarf galaxies around it. In March 20 15, scientists found that the size of the Milky Way is 50% larger than previously thought. Andromeda galaxy looks like a spindle-shaped oval spot in the northeast sky and is one of the most distant celestial bodies visible to the naked eye. It is generally believed that Andromeda galaxy is the largest galaxy in this galaxy group, and its appearance is similar to that of the Milky Way. The members of this galaxy group are Andromeda, Milky Way, Triangle and about 50 small galaxies. According to the improved measurement technology and recent research data, scientists believe that there are many dark matter in the Milky Way, and the mass ratio of dark matter is the largest in this galaxy group. Andromeda and the Milky Way are both in this galaxy group, and their diameters are at least 1.6 times that of the Milky Way. Andromeda galaxy is the largest galaxy in this galaxy group, and it is moving towards the Milky Way at a speed of 300 kilometers per second. After 3 billion to 4 billion years, it may hit the Milky Way and finally synthesize an elliptical galaxy. Observations from the Spitzer Space Telescope show that Andromeda has nearly one trillion stars, far more than the Milky Way. In 2006, the mass of the Milky Way was re-estimated to be about 50% of Andromeda.