Resumen de Portrait of a black hole.

Avery E. Broderick, Abraham Loeb

• The article discusses attempt by astronomers to produce images of the supermassive black holes that lie at the center of the Milky Way and M87 galaxies, such as Satittarius A* (Sgr A*), through the construction of a network of radio telescopes. Topics include an explanation of event horizons, which is the central feature of a black hole, why astronomers have difficulty viewing black holes directly, such as their extreme gravity, and how better studies could explain black hole phenomena. INSET: DISTANT SIGNS OF BLACK HOLES.