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Earth formed in this manner about 4.54 billion years ago (with an uncertainty of 1%) [25] [26] [4] and was largely completed within 10–20 million years. [27] In June 2023, scientists reported evidence that the planet Earth may have formed in just three million years, much faster than the 10−100 million years thought earlier.
The Moon formed soon afterwards, possibly as a result of the impact of a large planetoid with the Earth. [ 12 ] [ 13 ] More recent potassium isotopic studies suggest that the Moon was formed by a smaller, high-energy, high-angular-momentum giant impact cleaving off a significant portion of the Earth. [ 14 ]
By 4.54 ± 0.04 Ga the primordial Earth had formed. [36] The bodies in the Solar System formed and evolved with the Sun. In theory, a solar nebula partitions a volume out of a molecular cloud by gravitational collapse, which begins to spin and flatten into a circumstellar disk, and then the planets
Each 45-minute episode focuses on different geologic features and processes of the Earth. The first season, spanning 13 episodes, concluded on May 5, 2009. The second season premiered on November 24, 2009. [3] [4] The first season of the television series was released as a four-volume Region 1 DVD box set on August 25, 2009.
Detail of a cubit rod in the Museo Egizio of Turin The earliest recorded systems of weights and measures originate in the 3rd or 4th millennium BC. Even the very earliest civilizations needed measurement for purposes of agriculture, construction and trade. Early standard units might only have applied to a single community or small region, with every area developing its own standards for ...
An early definition of the metre was one ten-millionth of the Earth quadrant, the distance from the North Pole to the Equator, measured along a meridian through Paris.. The history of the metre starts with the Scientific Revolution that is considered to have begun with Nicolaus Copernicus's publication of De revolutionibus orbium coelestium in 1543.
In 1862, the physicist William Thomson, 1st Baron Kelvin published calculations that fixed the age of Earth at between 20 million and 400 million years. [19] [20] He assumed that Earth had formed as a completely molten object, and determined the amount of time it would take for the near-surface temperature gradient to decrease to its present value.
Instead, the result was originally expressed as the relative density of Earth, [5] or equivalently the mass of Earth. His experiment gave the first accurate values for these geophysical constants. The experiment was devised sometime before 1783 by geologist John Michell , [ 6 ] [ 7 ] who constructed a torsion balance apparatus for it.