The first low surface
brightness galaxy to be discovered and the largest spiral
galaxy known; it lies about one billion light-years away in Coma
Berenices. Despite its diameter of nearly 600,000 light-years and mass
of over two trillion solar masses, its gas-rich disk is so faint that it
was found only by accident in 1987 by American astronomers Christopher Impey
and Gregory Bothun on photographic plates processed by the English-born
astronomer and photographer (now based in Australia) David Malin (1941–).