who wrote the book entitled of the revolutions of celestial spheres (de revolutionibus)
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 (1473â€“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.
Nebular hypothesis The birth of the modern widely accepted theory of planetary formation—the solar nebular disk model (SNDM)—can be traced to the Soviet astronomer Victor Safronov.[8] His 1969 book Evolution of the protoplanetary cloud and formation of the Earth and the planets,[9] which was translated to English in 1972, had a long-lasting effect on the way scientists think about the formation of the planets.[10] In this book almost all major problems of the planetary formation process were formulated and some of them solved. Safronov's ideas were further developed in the works of George Wetherill, who discovered runaway accretion.[2] While originally applied only to the Solar System, the SNDM was subsequently thought by theorists to be at work throughout the Universe; as of 8 September 2017 astronomers have discovered 3,667 extrasolar planets in our galaxy.[11]