astroengine writes "Say "hello" to one of the biggest cosmic clashes you'll ever witness. Announced at the American Astronomical Society meeting in Austin, Texas on Tuesday, the most distant galactic cluster merger has been discovered. Dubbed "El Gordo" — meaning "the big one" or "the fat one" in Spanish — the merger is located 7 billion light-years away. Cluster mergers such as El Gordo, and its famous cousin the "Bullet Cluster", are important to astronomers as the gravitational effects of dark matter can be studied over very large scales."
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