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.
Eighteen-year-olds were the largest age cohort in the first year of the war in both armies. Soldiers
Wassily Kandinsky, Black Lines (Schwarze Linien).
Attributed to José de Alcíbar, From Spaniard and Black, Mulatto (De Español y Negra, Mulato).
Colon with diverticulosis. An inflamed or infected diverticulum is called diverticulitis.
Notice the small motor gear on the left drives a larger plastic gear (black), which then drives ...
Life cycle of Rhizopus stolonifer, a black bread mold