Although the geography of the Milky Way is still poorly understood, astronomers estimate that it spans between 120,000 and 180,000 light years, around the supermassive black hole Sagittarius A *. The Sun is in a small structure called the arm or spur of Orion, between the arms of Sagittarius and Perseus, about 26,000 light years from the nucleus. In this hectic activity unfolds. More stars are created in it than in the galactic suburbs where we live, and the most massive of them expel their outer layers in the form of extremely violent winds. At the same time, the entire region is traversed by supersonic shock waves, the product of the gigantic explosions with which stars that have a mass several times greater than that of the sun king end their lives.
Just four decades ago, no one imagined this pyrotechnic show taking place, but advances in radio astronomy and infrared astronomy have changed our view of the bustling galactic center.
Beautifully shaped, large and symmetrical, the Milky Way looks like a finished product, but in recent years we have discovered that it is yet to be finished. It continues to collect cosmic material, gobbling up small, faint galaxies that venture nearby and risk being trapped in its gravitational well. In fact, one of the most widespread hypotheses at this time is that our cosmic city, and others like it, have grown thanks to this slow but continuous work of collection.
Today the process continues, albeit at a slower pace. At present, a small spheroidal galaxy is falling on the disk of the Milky Way; Fortunately, on the other side of where we are. It was discovered by chance in 1994, and its mass is 1% that of ours. The Milky Way's gravity is stretching it like a pastry chef does with its dough. In fact, a team of astronomers from the Instituto de Astrofísica de Canarias has found part of its debris just over 18,000 light years from the center of our galaxy. Will this intergalactic feast ever end? Not at least for the next 4 billion years. By then, the Andromeda galaxy and ours will merge in a long and deep cosmic embrace.
You can read the full article "What a galaxy move!", Written by Miguel Ángel Sabadell, in issue 426 of Muy Interesante.
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