Size of NGC 1277's Black Hole (IMAGE) University of Texas at Austin Caption This diagram shows how the diamater of the 17-billion-solar-mass black hole in the heart of galaxy NGC 1277 compares with the orbit of Neptune around the Sun. The black hole is eleven times wider than Neptune's orbit. Shown here in two dimensions, the "edge" of the black hole is actually a sphere. This boundary is called the "event horizon," the point from beyond which, once crossed, neither matter nor light can return. Credit D. Benningfield/K. Gebhardt/StarDate Usage Restrictions None License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.