The Cosmic Calendar is a method to visualize the chronology of the universe, scaling its currently understood age of 13.8 billion years to a single year in order to help intuit it for pedagogical purposes in science education or popular science.
In this visualization, the Big Bang took place at the beginning of January 1 at midnight, and the current moment maps onto the end of December 31 just before midnight. At this scale, there are 437.5 years per cosmic second, 1.575 million years per cosmic hour, and 37.8 million years per cosmic day.
The concept was popularized by Carl Sagan in his 1977 book The Dragons of Eden and on his 1980 television series Cosmos. Sagan goes on to extend the comparison in terms of surface area, explaining that if the Cosmic Calendar is scaled to the size of a football field, then "all of human history would occupy an area the size of [his] hand".
|Date||Gya (billion years ago)||Event|
|1 Jan||13.8||Big Bang, as seen through cosmic background radiation, which would have been last emitted 14 minutes after midnight|
|19 Jan||13.1||Oldest known Gamma Ray Burst|
|26 Jan||12.85||First galaxies form|
|16 Mar||11||Milky Way Galaxy formed|
|13 May||8.8||Milky Way Galaxy disk formed|
|2 Sep||4.57||Formation of the Solar System|
|6 Sep||4.4||Oldest rocks known on Earth|
Date in year calculated from formula
T(days) = 365 days * ( 1- T_Gya/13.797 )
Evolution of life on Earth
|Date||Gya (billion years ago)||Event|
|14 Sep||4.1||First known remains of biotic life (discovered in 4.1 billion-year-old rocks in Western Australia).|
|21 Sep||3.8||First Life (Prokaryotes)|
|29 Oct||2.4||Oxygenation of atmosphere|
|9 Nov||2||Complex cells (Eukaryotes)|
|5 Dec||0.8||First multicellular life|
|7 Dec||0.67||Simple animals|
|14 Dec||0.55||Arthropods (ancestors of insects, arachnids)|
|17 Dec||0.5||Fish and Proto-amphibians|
|20 Dec||0.45||Land plants; Ordovician–Silurian extinction events|
|21 Dec||0.4||Insects and seeds|
|22 Dec||0.36||Amphibians; Late Devonian extinction|
|24 Dec||0.25||Permian–Triassic extinction event; 57% of all biological families and 83% of all genera die|
|26 Dec||0.2||Mammals; Triassic–Jurassic extinction event|
|27 Dec||0.15||Birds (avian dinosaurs)|
|30 Dec, 06:24||0.065||Cretaceous–Paleogene extinction event, non-avian dinosaurs die out|
|Date / time||Mya (million years ago)||Event|
|31 Dec, 06:05||15||Apes|
|31 Dec, 14:24||12.3||Hominids|
|31 Dec, 22:24||2.5||Primitive humans and stone tools|
|31 Dec, 23:44||0.4||Domestication of fire|
|31 Dec, 23:52||0.2||Anatomically modern humans|
|31 Dec, 23:55||0.11||Beginning of most recent Glacial Period|
|31 Dec, 23:58||0.035||Sculpture and painting|
|31 Dec, 23:59:32||0.012||Agriculture|
- Geologic Calendar
- Big History – Academic discipline which examines history from the Big Bang to the present
- Detailed logarithmic timeline – Timeline of the history of the universe, Earth, and mankind
- List of timelines
- Timeline of ancient history
- Timeline of early modern history
- Timeline of the evolutionary history of life – Current scientific theory outlining the major events during the development of life
- Timeline of the far future – Scientific projections regarding the far future
- Timeline of human evolution – Chronological outline of major events in the development of the human species
- Timeline of human prehistory
- Timelines of modern history
- Timeline of natural history
- Timeline of plant evolution – Chronological outline of major events in the development of plants
- Chronology of the universe – History and future of the universe
- Timeline of the Middle Ages – Timeline
- Cosmic time
- History of Earth – Development of planet Earth from its formation to the present day
- Therese Puyau Blanchard (1995). "The Universe At Your Fingertips Activity: Cosmic Calendar". Astronomical Society of the Pacific. Archived from the original on 2007-12-16. Retrieved 2007-12-15.
- Cosmos, episode 1 (1980)
- Episode 1: The Shores of the Cosmic Ocean (Cosmos: A Personal Voyage, Carl Sagan)
- "First Galaxies Born Sooner After Big Bang Than Thought". Space.com. Retrieved 2015-11-07.
- Borenstein, Seth (19 October 2015). "Hints of life on what was thought to be desolate early Earth". Excite. Yonkers, NY: Mindspark Interactive Network. Associated Press. Retrieved 2015-10-20.
- Bell, Elizabeth A.; Boehnike, Patrick; Harrison, T. Mark; et al. (19 October 2015). "Potentially biogenic carbon preserved in a 4.1 billion-year-old zircon" (PDF). Proc. Natl. Acad. Sci. U.S.A. 112 (47): 14518–21. Bibcode:2015PNAS..11214518B. doi:10.1073/pnas.1517557112. ISSN 1091-6490. PMC 4664351. PMID 26483481. Retrieved 2015-10-20. Early edition, published online before print.
- Yoko Ohtomo; Takeshi Kakegawa; Akizumi Ishida; Toshiro Nagase; Minik T. Rosing (8 December 2013). "Evidence for biogenic graphite in early Archaean Isua metasedimentary rocks". Nature Geoscience. 7: 25–28. Bibcode:2014NatGe...7...25O. doi:10.1038/ngeo2025.
- Borenstein, Seth (13 November 2013). "Oldest fossil found: Meet your microbial mom". AP News. Retrieved 15 November 2013.
- Noffke, Nora; Christian, Daniel; Wacey, David; Hazen, Robert M. (8 November 2013). "Microbially Induced Sedimentary Structures Recording an Ancient Ecosystem in the ca. 3.48 Billion-Year-Old Dresser Formation, Pilbara, Western Australia". Astrobiology. 13 (12): 1103–24. Bibcode:2013AsBio..13.1103N. doi:10.1089/ast.2013.1030. PMC 3870916. PMID 24205812.
- Erwin, Douglas H. (9 November 2015). "Early metazoan life: divergence, environment and ecology". Phil. Trans. R. Soc. B. 370 (20150036): 20150036. doi:10.1098/rstb.2015.0036. PMC 4650120. PMID 26554036.
- "Cosmos: A Spacetime Odyssey (@35min)". Archived from the original on 2014-03-11. Retrieved 2014-03-11.