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The earliest undisputed evidence of life on Earth dates at least from 3.5 billion years ago, [7] [8] [9] during the Eoarchean Era, after a geological crust started to solidify following the earlier molten Hadean eon. There are microbial mat fossils such as stromatolites found in 3.48 billion-year-old sandstone discovered in Western Australia.
It is commonly used as a unit of time to denote length of time before the present in 10 9 years. This initialism is often used in the sciences of astronomy , geology , and paleontology . The "billion" in bya is the 10 9 "billion" of the short scale of the U.S. , [ 1 ] not the long-scale 10 12 "billion" of some European usage.
Although the term aeon may be used in reference to a period of a billion years (especially in geology, cosmology and astronomy), its more common usage is for any long, indefinite period. Aeon can also refer to the four aeons on the geologic time scale that make up the Earth's history, the Hadean , Archean , Proterozoic , and the current aeon ...
Planetary scientists have, for instance, struggled to explain how a major collision created the moon 4.35 billion years ago, at a time in the solar system’s history when most large celestial ...
Known affectionately to scientists as the "boring billion," there was a seemingly endless period in the world's history when the length of a day stayed put. The time when a day on Earth was just ...
The age of Earth is estimated to be 4.54 ± 0.05 billion years ... history from the beginning of life to today has taken place since 3.5 to 3.8 billion years ago, ...
According to evidence from radiometric dating and other sources, Earth formed about 4.54 billion years ago. [7] [8] [9] The current dominant theory of planet formation suggests that planets such as Earth form in about 50 to 100 million years but more recently proposed alternative processes and timescales have stimulated ongoing debate in the planetary science community. [10]
A new study says complex life began 1.5 billion years ... from University College London—told the BBC that even if this basin did contain higher-than-normal nutrients 2.1 billion years ago, ...