De revolutionibus orbium coelestium De revolutionibus orbium coelestium De revolutionibus orbium coelestium ("On the Revolutions of the Heavenly Spheres") is the seminal work on the heliocentric theory of the Renaissance astronomer Nicolaus Copernicus (1473–1543). The book, first printed in 1543 in Nuremberg, Holy Roman Empire, offered an alternative model of the universe to Ptolemy's geocentric system, which had been widely accepted since ancient times. Copernicus initially outlined his system in a short, untitled, anonymous manuscript that he distributed to several friends, referred to as the "Commentariolus". A physician's library list dating to 1514 includes a manuscript whose description matches the "Commentariolus", so Copernicus must
The Shadow of the Sun rural villages which gave him an honest perspective on what was the current situation of the continent. The Shadow of the Sun The Shadow of the Sun (, literally "Ebony") is a travel memoir by the Polish writer and journalist Ryszard Kapuściński. It was published by Penguin Books in 2001 with the English translation by Klara Glowczewska. Kapuściński spent nearly 30 years in various African countries such as Kenya, Rwanda, Nigeria, Ethiopia and more, detailing his accounts as a white, foreign visitor, of the development of the African states. Kapuściński's experience in Africa was unique, because he had the opportunity