The Advanced Camera for Surveys aboard the Hubble Space Telescope has provided many of the observatory’s most spectacular – and scientifically valuable – images. NASA and ESA present samples of its work in a 20th anniversary collection.
Most galaxies are clumped together in groups or clusters. A neighbouring galaxy is never far away. But this galaxy, known as NGC 6503, has found itself in a lonely position, at the edge of a strangely empty patch of space called the Local Void.