Early Earth
{{Short description|Period in Earth's history}}
Early Earth also known as Proto-Earth is loosely defined as Earth in its first one billion years, or gigayear (Ga, 109 y),{{Cite journal |last=Rankama |first=Kalervo |date=May 1967 |title=Megayear and Gigayear: Two Units of Geological Time |journal=Nature |language=en |volume=214 |issue=5088 |pages=634 |doi=10.1038/214634a0 |bibcode=1967Natur.214..634R |issn=1476-4687 |doi-access=free}} from its initial formation in the young Solar System at about 4.55 Ga to some time in the Archean eon in approximately 3.5 Ga.{{cite book |title=Earth System: History and Natural Variability Volume I |chapter=Early Earth |editor=Vaclav Cilek |date=2009 |publisher=Eolss Publishers |isbn=978-1-84826-104-4 |url=https://www.eolss.net/ebooklib/bookinfo/earth-system-history-natural-variability.aspx |page=98}} On the geologic time scale, this comprises all of the Hadean eon, starting with the formation of the Earth about 4.6 billion years ago,{{cite web |title=International Chronostratigraphic Chart 2015 |url=http://www.stratigraphy.org/ICSchart/ChronostratChart2015-01.pdf |publisher=ICS |access-date=23 January 2016}} and the Eoarchean, starting 4 billion years ago, and part of the Paleoarchean era, starting 3.6 billion years ago, of the Archean eon.
This period of Earth's history involved the planet's formation from the solar nebula via a process known as accretion. This time period included intense meteorite bombardment as well as giant impacts, including the Moon-forming impact, which resulted in a series of magma oceans and episodes of core formation.{{Cite journal |last1=Carlson |first1=Richard W. |last2=Garnero |first2=Edward |last3=Harrison |first3=T. Mark |last4=Li |first4=Jie |last5=Manga |first5=Michael |last6=McDonough |first6=William F. |last7=Mukhopadhyay |first7=Sujoy |last8=Romanowicz |first8=Barbara |author-link8=Barbara A. Romanowicz |last9=Rubie |first9=David |date=2014-01-01 |title=How Did Early Earth Become Our Modern World? |journal=Annual Review of Earth and Planetary Sciences |volume=42 |issue=1 |pages=151–178 |doi=10.1146/annurev-earth-060313-055016 |bibcode=2014AREPS..42..151C |doi-access=free}} After formation of the core, meteorites or comets may have delivered water and other volatile compounds to the Earth in a "late veneer".{{Cite journal |last1=Drake |first1=Michael J. |last2=Righter |first2=Kevin |date=2002-03-07 |title=Determining the composition of the Earth |journal=Nature |language=en |volume=416 |issue=6876 |pages=39–44 |doi=10.1038/416039a |pmid=11882886 |issn=0028-0836 |bibcode=2002Natur.416...39D |s2cid=4380038}} Although little crustal material from this period survives, the oldest dated specimen is a zircon mineral of 4.404 ± 0.008 Ga enclosed in a metamorphosed sandstone conglomerate in the Jack Hills of the Narryer Gneiss terrane of Western Australia.{{Cite journal |last1=Wilde |first1=Simon A. |last2=Valley |first2=John W. |last3=Peck |first3=William H. |last4=Graham |first4=Colin M. |date=2001-01-11 |title=Evidence from detrital zircons for the existence of continental crust and oceans on the Earth 4.4 Gyr ago : Abstract : Nature |journal=Nature |volume=409 |issue=6817 |pages=175–178 |doi=10.1038/35051550 |issn=0028-0836 |pmid=11196637 |bibcode=2001Natur.409..175W |s2cid=4319774}} The earliest supracrustals (such as the Isua greenstone belt) date from the latter half of this period, about 3.8 Ga, around the same time as peak Late Heavy Bombardment.
History
According to evidence from radiometric dating and other sources, Earth formed about 4.54 billion years ago.{{cite web |date=1997 |title=Age of the Earth |url=http://pubs.usgs.gov/gip/geotime/age.html |publisher=U.S. Geological Survey |access-date=2006-01-10 |archive-url=https://web.archive.org/web/20051223072700/http://pubs.usgs.gov/gip/geotime/age.html |archive-date=23 December 2005 |url-status=live}}{{cite journal |last=Dalrymple |first=G. Brent |title=The age of the Earth in the twentieth century: a problem (mostly) solved |journal=Special Publications, Geological Society of London |date=2001 |volume=190 |issue=1 |pages=205–221 |doi=10.1144/GSL.SP.2001.190.01.14 |bibcode=2001GSLSP.190..205D |s2cid=130092094}}
{{cite journal |author=Manhesa, Gérard |author2=Allègre, Claude J. |author3=Dupréa, Bernard |author4=Hamelin, Bruno |name-list-style=amp |title=Lead isotope study of basic-ultrabasic layered complexes: Speculations about the age of the earth and primitive mantle characteristics |journal=Earth and Planetary Science Letters |date=1980 |volume=47 |issue=3 |pages=370–382 |doi=10.1016/0012-821X(80)90024-2 |bibcode=1980E&PSL..47..370M}} 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. For example, in June 2023, one team of scientists reported evidence that Earth may have formed in just three million years.{{cite news |last=Patel |first=Kasha |title=Scientists have a controversial theory for how — and how fast — Earth formed |url=https://www.washingtonpost.com/climate-environment/2023/06/16/earth-formation-pebble-accretion-theory/ |date=16 June 2023 |newspaper=The Washington Post |url-status=live |archive-url=https://archive.today/20230617115127/https://www.washingtonpost.com/climate-environment/2023/06/16/earth-formation-pebble-accretion-theory/ |archive-date=17 June 2023 |access-date=17 June 2023}}{{cite journal |author=Onyett, Isaac J. |display-authors=et al. |title=Silicon isotope constraints on terrestrial planet accretion |date=14 June 2023 |journal=Nature |volume=619 |issue=7970 |pages=539–544 |doi=10.1038/s41586-023-06135-z |pmid=37316662 |s2cid=259161680 |pmc=10356600 |bibcode=2023Natur.619..539O}} Nonetheless, within the first billion years of the formation of Earth,{{cite book |first1=G.B. |last1=Dalrymple |date=1991 |title=The Age of the Earth |publisher=Stanford University Press |location=California |isbn=978-0-8047-1569-0}}{{cite web |last=Newman |first=William L. |date=2007-07-09 |url=http://pubs.usgs.gov/gip/geotime/age.html |title=Age of the Earth |publisher=Publications Services, USGS |access-date=2007-09-20}}{{cite journal |last1=Dalrymple |first1=G. Brent |title=The age of the Earth in the twentieth century: a problem (mostly) solved |journal=Geological Society, London, Special Publications |date=2001 |volume=190 |issue=1 |pages=205–21 |url=http://sp.lyellcollection.org/cgi/content/abstract/190/1/205 |access-date=2007-09-20 |doi=10.1144/GSL.SP.2001.190.01.14 |bibcode=2001GSLSP.190..205D |s2cid=130092094}}{{cite web |last1=Stassen |first1=Chris |date=2005-09-10 |url=http://www.talkorigins.org/faqs/faq-age-of-earth.html |title=The Age of the Earth |publisher=TalkOrigins Archive |access-date=2008-12-30}}
life appeared in its oceans and began to affect its atmosphere and surface, promoting the proliferation of aerobic as well as anaerobic organisms. Since then, the combination of Earth's distance from the Sun, its physical properties and its geological history have allowed life to emerge, develop photosynthesis, and, later, evolve further and thrive. The earliest life on Earth arose at least 3.5 billion years ago.Schopf, JW, Kudryavtsev, AB, Czaja, AD, and Tripathi, AB. (2007). Evidence of Archean life: Stromatolites and microfossils. Precambrian Research 158:141–155.Schopf, JW (2006). Fossil evidence of Archaean life. Philos Trans R Soc Lond B Biol Sci 29;361(1470) 869-85.{{cite book |first1=Peter |last1=Hamilton Raven |first2=George |last2=Brooks Johnson |title=Biology |url=https://archive.org/details/biologyrave00rave |url-access=registration |date=2002 |publisher=McGraw-Hill Education |isbn=978-0-07-112261-0 |page=[https://archive.org/details/biologyrave00rave/page/68 68] |access-date=7 July 2013}} Earlier possible evidence of life includes graphite, which may have a biogenic origin, in 3.7-billion-year-old metasedimentary rocks discovered in southwestern Greenland{{cite journal |last1=Ohtomo |first1=Yoko |last2=Kakegawa |first2=Takeshi |last3=Ishida |first3=Akizumi |last4=Nagase |first4=Toshiro |last5=Rosing |first5=Minik T. |display-authors=3 |date=January 2014 |title=Evidence for biogenic graphite in early Archaean Isua metasedimentary rocks |journal=Nature Geoscience |volume=7 |issue=1 |pages=25–28 |bibcode=2014NatGe...7...25O |doi=10.1038/ngeo2025 |issn=1752-0894}} and 4.1-billion-year-old zircon grains in Western Australia.{{cite news |last=Borenstein |first=Seth |title=Hints of life on what was thought to be desolate early Earth |url=http://apnews.excite.com/article/20151019/us-sci--earliest_life-a400435d0d.html |date=19 October 2015 |work=Excite |location=Yonkers, NY |publisher=Mindspark Interactive Network |agency=Associated Press |access-date=2015-10-20}}{{cite journal |last1=Bell |first1=Elizabeth A. |last2=Boehnike |first2=Patrick |last3=Harrison |first3=T. Mark |last4=Mao |first4=Wendy L. |display-authors=3 |date=19 October 2015 |title=Potentially biogenic carbon preserved in a 4.1 billion-year-old zircon |url=http://www.pnas.org/content/early/2015/10/14/1517557112.full.pdf |journal=Proc. Natl. Acad. Sci. U.S.A. |doi=10.1073/pnas.1517557112 |issn=1091-6490 |access-date=2015-10-20 |pmid=26483481 |pmc=4664351 |volume=112 |issue=47 |pages=14518–21 |bibcode=2015PNAS..11214518B |doi-access=free}} Early edition, published online before print.
In November 2020, an international team of scientists reported studies suggesting that the primeval atmosphere of the early Earth was very different from the conditions used in the Miller–Urey studies considering the origin of life on Earth.{{cite news |last=Zurich |first=Eth |title=Uncovering Mysteries of Earth's Primeval Atmosphere 4.5 Billion Years Ago and the Emergence of Life |url=https://scitechdaily.com/uncovering-mysteries-of-earths-primeval-atmosphere-4-5-billion-years-ago-and-the-emergence-of-life/ |date=29 November 2020 |access-date=30 November 2020}}
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| NASA-EarlyEarth-PaleOrangeDot-20190802.jpg
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| Artist's impression of Archean Earth, showing an orange atmospheric haze, leading to the alternative description of the planet in that stage of its development as a "pale orange dot"{{cite journal |url=https://ui.adsabs.harvard.edu/abs/2014AGUFMPP53A1202A/abstract |bibcode=2014AGUFMPP53A1202A |title=The Pale Orange Dot: Spectral Effects of a Hazy Early Earth |last1=Arney |first1=G. N. |last2=Meadows |first2=V. S. |last3=Domagal-Goldman |first3=S. D. |last4=Claire |first4=M. |last5=Schwieterman |first5=E. |journal=AGU Fall Meeting Abstracts |date=2014 |volume=2014}}{{cite web |url=https://www.nasa.gov/centers-and-facilities/goddard/nasa-team-looks-to-ancient-earth-first-to-study-hazy-exoplanets/ |title=NASA Team Looks to Ancient Earth First to Study Hazy Exoplanets - NASA |date=8 February 2017}}
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| A reconstruction of what the Earth may have looked like from space in the early Orosirian, 2 billion years ago, with red oceans due to a high concentration of oxygen, causing banded iron formations
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See also
{{div col|colwidth=30em}}
- {{annotated link|Chronology of the universe}}
- {{annotated link|History of life}}
- {{annotated link|Future of Earth}}
- {{annotated link|Geological history of Earth}}
- {{annotated link|History of Earth}}
- {{annotated link|Timeline of the evolutionary history of life}}
- {{annotated link|Timeline of natural history}}
{{div col end}}
References
{{Reflist|30em}}
External links
{{Spoken Wikipedia|date=2024-12-29|Narration of Early Earth.mp3}}
- [https://nightsky.jpl.nasa.gov/docs/HowFast.pdf Earth – Speed through space – about 1 million miles an hour] – NASA and (WP discussion)
{{Earth science}}
{{portalbar|Biology|Earth sciences}}