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"
Gemini North Images Bow Shock Near Galactic Center
17/10/2000
What's going on near the center of our Galaxy? Glowing across the electromagnetic spectrum, the center of our Milky Way Galaxy is thought to be home to massive stars, rotating gas rings, and a massive black hole. Now the central Galactic zoo just got larger. The 8-meter Gemini North telescope in Hawaii in its first scientific observation has just imaged the Galactic Center and revealed a star only three light years out colliding with gas and dust. The bow shock, similar to that caused by a boat moving through water, appears arrow-shaped and is visible on the upper right of the above photograph taken in representative infrared colors. Gemini's new flexible-mirror technology has imaged this structure, known as IRS8, in finer detail than ever before.