They are found within the bounds of the ocean floor and in the transitional zone and are divided into two morphological typesâflat, or subhorizontal, and hilly. Flat abyssal plains are confined to the margins of ocean basins or to the centers of the basins of epicontinental seas. Hilly abyssal plains occupy a large part of the bottom of the ocean floor. The surface of the flat abyssal plain is characterized by exceptional evenness, with floor gradients of less than 0.001. Starkly contrasting solitary seamounts, evidently of volcanic origin, are also found.
The first person to do so ever was as early as the 3rd century BC by Aristarchus of Samos. Unfortunately, his notion gained only few supporters and was summarily rejected. Later in the 16th century, Nicholas Copernicus presented a mathematical model. In the next century, Johannes Kepler made inclusions of elliptical orbits, and Galileo Galilei presented supporting observations made using a telescope.
Galileo is famous for discovering the Galilean moons (Jupiter's four largest moons--Io, Ganymede, Europa, and Callisto) Galileo is most famous for his scientific hypothesis that the Earth revolves around the sun, rather than the sun revolving around Earth, as most people believed in that day. He went to trial for his hypothesis because of its apparent contradictory nature to the Scripture, or Bible.