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
Earth in the Balance to react in time to save our skins”. Earth in the Balance Earth in the Balance: Ecology and the Human Spirit (, paperback ) is a 1992 book written by Al Gore, published in June 1992, shortly before he was elected Vice President in the 1992 presidential election. Known by the short title "Earth in the Balance", the book explains the world's ecological predicament and describes a range of policies to deal with the most pressing problems. It includes a proposed "Global Marshall Plan" to address current ecological issues. Written while his son was recovering from a serious accident, "Earth