A female motorcycle cop directs traffic wearing crash helmet, Haywarket Square, Boston, Massachusetts, 1979. (Photo by Spencer Grant/Getty Images)

Mounted cop in action on Tremont Street in Boston, Massachusetts, 1920 – 1929 (approximate). (Photo by Leslie Jones)

Prostitutes working on 10th Ave in New York, USA on June 29, 1997. (Photo by Jon Naso/NY Daily News Archive via Getty Images)

Indigenous dancers participate in a traditional healing ceremony for the mother earth at El Salvador del Mundo Square in San Salvador, December 10, 2014. Salvadorean indigenous organizations participated in a ceremony to ask for solutions to stop climate change and respect planet earth as the U.N. Climate Change Conference COP 20 is bring held in Peru. The two-week long United Nations climate summit opened on December 1 in Lima, with experts and analysts from around the world gathering to discuss melting glaciers and extreme weather patterns. (Photo by Jose Cabezas/Reuters)

The Hubble Space Telescope is shown following its release from the space shuttle Discovery Wednesday, February 19, 1997. The Hubble Space Telescope, one of NASA'S crowning glories, marks its 25th anniversary on Friday, April 24, 2015. With more than 1 million observations, including those of the farthest and oldest galaxies ever beholden by humanity, no man-made satellite has touched as many minds or hearts as Hubble. (Photo by AP Photo/NASA)

Photograph of model Czech-Italian Eva Herzigova taken by Italian photographer Gian Paolo Barbieri in Rome, Italy, 1997. (Photo by Gian Paolo Barbieri/Fondazione Gian Paolo Barbieri/29 ARTS IN PROGRESS gallery/Handout via Reuters)

Porcelain Black performs during the ' I Am Still Music' Tour at the Wells Fargo Center on March 26, 2011 in Philadelphia, Pennsylvania