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Earth formed about 4.54 billion years ago by accretion from the solar nebula, a disk-shaped mass of dust and gas left over from the formation of the Sun, which also created the rest of the Solar System. Initially, Earth was molten due to extreme volcanism and frequent collisions with other bodies.
The geological time scale (GTS), as defined by international convention, [3] depicts the large spans of time from the beginning of Earth to the present, and its divisions chronicle some definitive events of Earth history. Earth formed around 4.54 billion years ago, approximately one-third the age of the universe, by accretion from the solar nebula.
Earth is the third planet from the ... 1.35 × 10 18 metric tons or about 1/4400 of Earth's ... years after Earth formed. Earth's life has been shaping ...
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.
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. [21] [22] 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.
Due to the strength of Christian beliefs during the 17th century, the theory of the origin of the Earth that was most widely accepted was A New Theory of the Earth published in 1696, by William Whiston. [10] Whiston used Christian reasoning to "prove" that the Great Flood had occurred and that the flood had formed the rock strata of the Earth.
Earth's shape is also slightly lumpy because it is composed of different materials of different densities that exert slightly different amounts of gravitational force per volume. The liquidity of a hot, newly formed planet allows heavier elements to sink down to the middle and forces lighter elements closer to the surface, a process known as ...
Goods of commerce were originally traded by number or volume. When weighing of goods began, units of mass based on a volume of grain or water were developed. The diverse magnitudes of units having the same name, which still appear today in our dry and liquid measures, could have arisen from the various commodities traded.