sentences:  Chapel Hill, along with Durham and Raleigh, makes up one of the three corners of the Research Triangle, so named in 1959 with the creation of Research Triangle Park, a research park between Durham and Raleigh.The Morehead Planetarium at UNC was, when it opened in 1949, one of only a handful of planetariums in the nation, and it has remained an important town landmark for Chapel Hill.During the Mercury, Gemini, and Apollo programs, astronauts were trained there.