30. BLACK HOLES

A black hole is a very high concentration of mass exercizing an enormous strong gravitation force. Even light cannot escape that force.


A supermassive black hole is a black hole with a mass of an order of magnitude between 10^5 and 10^10 (hundreds of thousands and tens of billions) of solar masses. It is currently thought that most, if not all galaxies, including the Milky Way, contain supermassive black holes at their galactic centers. Most smaller black holes are generated from collapsing stars, which range up to perhaps 10 solar masses. The minimal supermassive black hole is in the range of a hundred thousand solar masses. There is a lot of evidence that Sagittarius A* is the supermassive black hole residing at the center of the Milky Way, calculated to have a mass of 3.7 million solar masses.
The hole itself is invisible, you see its surroundings in the galactic centre, to be found in the constellation "Sagittarius".
The first picture shows an artist's conception (top) of a supermassive black hole drawing material from a nearby star. At the bottom: images believed to show a supermassive black hole devouring a star in galaxy RXJ 1242-11, at the left side: X-ray image, at the right side: optical image.

This 400 by 900 lightyear mosaic of several Chandra images of the central region of our Milky Way galaxy reveals hundreds of white stars, neutron stars and small black holes bathed in an incandescent fog of multimillion-degree gas. The supermassive black hole at the center of the galaxy is located inside the bright white patch in the center of the image. The colors indicate X-ray energy bands: red (low) - green (medium) - blue (high).
A still more accurate photo is given in the third picture.
The white spots indicate the real centre.