Astronomy Picture of the Day

Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.

2014 February 24

The Cloudy Cores of Active Galaxies
Image Credit: NASA's GSFC, W. Steffen (UNAM)

Explanation: What would it look like to travel to the center of an active galaxy? Most galactic centers are thought to house black holes millions of times more massive than our Sun. The spaces surrounding these supermassive black holes may be far from dormant, however, flickering in many colors and earning the entire object class the title of Active Galactic Nuclei (AGN). Pictured above is a video illustrating how an active galactic nucleus may appear up close. AGN typically sport massive accretion disks feeding the central black hole, as well as powerful jets shooting electrically charged matter far into the surrounding universe. Clouds of gas and dust seen orbiting the central black holes have recently been found to be so dense that they intermittently eclipse even penetrating x-rays from reaching us. These X-ray dimming events, as short as hours but as long as years, were detected in an analysis encompassing over a decade of data taken by the NASA's orbiting Rossi X-ray Timing Explorer (RXTE).

Tomorrow's picture: sister threads

< | Archive | Index | Search | Calendar | RSS | Education | About APOD | Discuss | >

Authors & editors: Robert Nemiroff (MTU) & Jerry Bonnell (UMCP)
NASA Official: Phillip Newman Specific rights apply.
NASA Web Privacy Policy and Important Notices
A service of: ASD at NASA / GSFC
& Michigan Tech. U.