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.
Black flies are blood-sucking insects who vector disease, like River Blindness, while feeding on hum
Austrian Black and Tan Hound
Black Hole Wind
Labeling of black cohosh: (b) back label with more health claims and FDA disclaimer
Luna Park at Coney Island was a vast living theater in which strollers were both spectators and acto
Life cycle of Rhizopus stolonifer, a black bread mold