This NASA site provides an introduction to black holes, including how black holes form and how they can be detected. Numerous links provide additional information. The site also contains a fun multiple-choice quiz, cool...

This website, from the National Radio Astronomy Observatory (NRAO), is an image gallery of the enormous mass at the center of the Milky Way galaxy. Each image is accompanied by a several-paragraph explanation. Links to...

This page, from the Andrea Ghez group at UCLA, provides a description of the group’s work in characterizing the center of the galaxy and the supermassive black hole believed to reside there. The site presents "Journey...