This illustration shows the possible surface of TRAPPIST-1f, one of the newly discovered planets in the TRAPPIST-1 system. Scientists using the Spitzer Space Telescope and ground-based telescopes have discovered that there are seven Earth-size planets in the system. Credits: NASA/JPL-Caltech.
A robot opens a door during the DARPA Robotics Challenge, California on 5 June 2015. Photo: Getty Images.
In the Indian bull-wrestling festival Jallikattu, young men struggle to grab the bulls by their sharpened horns or jump on their backs as the beasts, festooned with marigolds, charge down the road (AFP Photo/ARUN SANKAR)
A crowd of women joining the National Woman Suffrage Association, which was led by Elizabeth Cady Stanton and Susan B. Anthony in 1869.(Photo: MPI/Getty Images)