1921, Halley’s Comet, Venus and a crescent moon being reflected in water. The comet appears once every 75 years. Interestingly, Mark Twain was born two weeks after the comet’s perihelion in 1835, and was quoted as saying that he would be going out with the comet as well. He died the day after the perihelion in 1910.
Astronomers have discovered the largest known structure in the universe, a clump of active galactic cores that stretch 4 billion light-years from end to end. The structure is a light quasar group (LQG), a collection of extremely luminous Galactic Nulcei powered by supermassive central black holes.