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This is an accepted version of this page This is the latest accepted revision, reviewed on 4 March 2025. There is 1 pending revision awaiting review. Scientific projections regarding the far future Several terms redirect here. For other uses, see List of numbers and List of years. Artist's concept of the Earth 5–7.5 billion years from now, when the Sun has become a red giant While the future ...
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.
A megaannus (Ma) represents one million (10 6) years. The geologic time scale or geological time scale ( GTS ) is a representation of time based on the rock record of Earth . It is a system of chronological dating that uses chronostratigraphy (the process of relating strata to time) and geochronology (a scientific branch of geology that aims to ...
The earliest evidence for life on Earth includes: 3.8 billion-year-old biogenic hematite in a banded iron formation of the Nuvvuagittuq Greenstone Belt in Canada; [30] graphite in 3.7 billion-year-old metasedimentary rocks in western Greenland; [31] and microbial mat fossils in 3.48 billion-year-old sandstone in Western Australia.
(10 9 days is roughly 2.738 million years.) About 10 9 months ago, dinosaurs walked the Earth during the late Cretaceous. (10 9 months is roughly 83.3 million years.) About 10 9 years—a gigaannus—ago, the first multicellular eukaryotes appeared on Earth. About 10 9 decades ago, the thin disk of the Milky Way started to form. (10 9 decades ...
From 1 billion years, and for about 12.8 billion years, the universe has looked much as it does today and it will continue to appear very similar for many billions of years into the future. The thin disk of our galaxy began to form when the universe was about 5 billion years old or 9 ± 2 Gya. [15]
An order of magnitude of time is usually a decimal prefix or decimal order-of-magnitude quantity together with a base unit of time, like a microsecond or a million years. In some cases, the order of magnitude may be implied (usually 1), like a "second" or "year". In other cases, the quantity name implies the base unit, like "century". In most ...
100 d (1 hd) 100 days, roughly equivalent to 1/4 of a year (91.25 days). In Chinese tradition "bǎi rì" is the hundredth day after one's birth, also called Baby's 100 Days Celebration. semester: 18 weeks: A division of the academic year. [6] Literally "six months", also used in this sense. lunar year: 354.37 d: year: 12 mo: 365 or 366 d ...