Name the socialite (1912-1990) who served as the president of the fundraising arm of the National Urban League from its founding in 1942 until her death. Through her many parties and her signature event, the Beaux Arts Ball, she raised millions of dollars, funding voting registration drives, among many other things. She is considered one of the more unsung heroes of the Civil Rights movement in the United States and has a last name that is a celestial object.