Black Hole
A black hole is an astronomical object whose gravity is so strong that nothing—even light—can escape from within its event horizon. It forms when a massive star’s core collapses or through other processes, and may have an accretion disk of infalling matter that emits radiation. Supermassive black holes at galaxy centers influence stellar orbits, and mergers produce gravitational waves.
Source: nasa.gov
APODs including "Black Hole"
The Circinus Galaxy
04/12/2000
Powerful forces are at play in the nearby Circinus Galaxy. Hot gas, colored pink, is being ejected out of the spiral galaxy from the central region. Much of Circinus' tumultuous gas, however, is concentrated in two rings. The outer ring, located about 700 light-years from the center, appears mostly red and is home to tremendous bursts of star formation. A previously unseen inner ring, inside the green disk above, is visible only 130 light years from the center on this recently released, representative color image taken by the Hubble Space Telescope. At the very center is an active galactic nucleus, where matter glows brightly before likely spiraling into a massive black hole. Although only 15 million light years distant, the Circinus Galaxy went unnoticed until 25 years ago because it is so obscured by material in the plane of our own Galaxy. The galaxy can be seen with a small telescope, however, in the constellation of Circinus.