Answer to Question 1
The escape velocity of a celestial object is the speed that an object on its surface needs to escape the gravitational field. A black hole is so dense that the escape velocity is greater than the speed of light, so light cannot escape the black hole; hence, the term black.
Answer to Question 2
It became known as the Copernican Revolution because it was not just the adoption of a new idea but a total change in the way astronomers, and, in fact, all of humanity, thought about Earth and its place in the Universe. In fact, our modern use of the words revolution and revolutionary to describe philosophical, political, and social upheavals comes from the title of Copernicus's book, De Revolutionibus, which means On Revolutions.
Herniated disk. A herniated disk is a protrusion of the disk’s gelatinous center, called the nucleus
Supermassive Black Hole
The Black Death spread over much of Europe in a three-year period in the middle of the fourteenth ce
In 1839 Mary Cragin, at the age of twenty-nine, became a convert to John Humphrey Noyes’s “communism
Black and White Out-Migration from Virginia and North and South Carolina, 1870–1940 (in thousands)
Detonation is a secondary ignition of the air–fuel mixture. It is also called spark knock or ...