A number of significant scientific events occurred in 2015. Gene editing based on CRISPR got significantly improved. A new human-like species, Homo naledi, was first described. Gravitational waves were observed for the first time, and dwarf planets Pluto and Ceres were visited by spacecraft for the first time. The United Nations declared 2015 the International Year of Soils and Light-based Technologies.
5 January: Detection of an unusually bright X-ray flare from Sagittarius A*, a supermassive black hole in the center of the Milky Way galaxy.