supermassive black hole core supergiant elliptical galaxy messier mass billion times sun depicted first false colour image radio waves released event horizon telescope april ref name nyt ref ref name apjl ref ref name nasa ref ref name bbc ref visible crescent shaped emission ring central shadow ref name ref gravitationally magnified views black hole 's photon ring photon capture zone event horizon crescent shape arises black hole 's rotation relativistic beaming shadow times diameter
Natural science Space science Astrophysics Black holes