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This model posits that, 4.6 billion years ago, the Solar System was formed by the gravitational collapse of a giant molecular cloud spanning several light-years. Many stars, including the Sun, were formed within this collapsing cloud. The gas that formed the Solar System was slightly more massive than the Sun itself.
Solar wind from the Sun created the heliosphere and swept away the remaining gas and dust from the protoplanetary disc into interstellar space. [23] Following the dissipation of the protoplanetary disk, the Nice model proposes that gravitational encounters between planetisimals and the gas giants caused each to migrate into different orbits ...
After small planetesimals—about 1 km in diameter—have formed by one way or another, runaway accretion begins. [20] It is called runaway because the mass growth rate is proportional to R 4 ~M 4/3, where R and M are the radius and mass of the growing body, respectively. [65] The specific (divided by mass) growth accelerates as the mass increases.
Pierre-Simon Laplace, one of the originators of the nebular hypothesis. Ideas concerning the origin and fate of the world date from the earliest known writings; however, for almost all of that time, there was no attempt to link such theories to the existence of a "Solar System", simply because it was not generally thought that the Solar System, in the sense we now understand it, existed.
Kerala-based astronomer Nilakantha Somayaji proposed a geoheliocentric system, in which the planets circled the Sun while the Sun, Moon and stars orbited the Earth. Finally, Polish astronomer Nicolaus Copernicus developed in full a system called Copernican heliocentrism, in which the planets and the Earth orbit the Sun, and the Moon orbits the ...
The ancient Hebrews, like all the ancient peoples of the Near East, believed the sky was a solid dome with the Sun, Moon, planets and stars embedded in it. [4] In biblical cosmology, the firmament is the vast solid dome created by God during his creation of the world to divide the primal sea into upper and lower portions so that the dry land could appear.
The timeline of discovery of Solar System planets and their natural satellites charts the progress of the discovery of new bodies over history. Each object is listed in chronological order of its discovery (multiple dates occur when the moments of imaging, observation, and publication differ), identified through its various designations (including temporary and permanent schemes), and the ...
c. 560 BCE – Anaximander is arguably the first to conceive a mechanical model of the world, although highly inaccurate: a cylindrical Earth [11] floats freely in space surrounded by three concentric wheels turning at different distances: the closest for the stars and planets, the second for the Moon and the farthest for the Sun, all conceived ...