The Cosmic Calendar is a method to visualize the chronology of the universe, scaling its current age of 13.8 billion years to a single year in order to help intuition in 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 second, 1.575 million years per hour, and 37.8 million years per day.
The concept was popularized by Carl Sagan in his book The Dragons of Eden (1977) and on his 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".
The Cosmic Year
The Cosmic Calendar shows the time-scale relationship of the universe and all events on Earth as plotted along a single 12-month, 365-day, year:
|1 Jan||13.8||Big Bang, as seen through cosmic background radiation|
|14 Jan||13.1||Oldest known Gamma Ray Burst|
|22 Jan||12.85||First galaxies form|
|16 Mar||11||Milky Way Galaxy formed|
|12 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 * 0.100/13.797 ( 1- T_Gya/13.797 )
Evolution of life on Earth
|14 Sep||4.1||"Remains of biotic life" found 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|
|21 Dec||0.4||Insects and Seeds|
|24 Dec||0.25||Permian-Triassic Extinction Event, 90% of Species Die Out|
|30 Dec, 06:24||0.065||Cretaceous–Paleogene extinction event, Non-avian Dinosaurs Die Out|
|Date / time||mya||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|
|Date / time||kya||Event|
|31 Dec, 23:59:33||12.0||End of the Ice Age|
|31 Dec, 23:59:46||6.0||Chalcolithic|
|31 Dec, 23:59:47||5.5||Early Bronze Age; Proto-writing|
|31 Dec, 23:59:48||5.0||First Dynasty of Egypt, Early Dynastic Period in Sumer|
|31 Dec, 23:59:49||4.5||Alphabet, Akkadian Empire, Wheel|
|31 Dec, 23:59:51||4.0||Code of Hammurabi, Middle Kingdom of Egypt|
|31 Dec, 23:59:52||3.5||Late Bronze Age to Early Iron Age|
|31 Dec, 23:59:53||3.0||Iron Age; Beginning of Classical Antiquity|
|31 Dec, 23:59:54||2.5||Buddha, Confucius, Qin Dynasty, Classical Greece, Ashokan Empire, Vedas Completed, Euclidean geometry, Archimedean Physics, Roman Republic|
|31 Dec, 23:59:55||2.0||Ptolemaic astronomy, Roman Empire, Christ, Invention of Numeral 0|
|31 Dec, 23:59:56||1.5||Muhammad, Maya civilization, Song Dynasty, Rise of Byzantine Empire|
|31 Dec, 23:59:58||1.0||Mongol Empire, Maratha Empire, Crusades, Christopher Columbus Voyages to the Americas, Renaissance in Europe, Classical Music to the Time of Johann Sebastian Bach|
The current second
|Date / time||kya||Event|
|31 Dec, 23:59:59||0.5||Modern History; the last 437.5 years before present.|
|Wikibooks has a book on the topic of: High School Earth Science|
|Wikibooks has a book on the topic of: General Astronomy/Short History of the Universe|
- Big History
- Detailed logarithmic timeline
- List of timelines
- Timeline of ancient history
- Timeline of early modern history
- Timeline of evolution
- Timeline of the far future
- Timeline of human evolution
- Timeline of human prehistory
- Timeline of modern history
- Timeline of natural history
- Timeline of plant evolution
- Timeline of the Big Bang
- Timeline of the Middle Ages
- Therese Puyau Blanchard (1995). "The Universe At Your Fingertips Activity: Cosmic Calendar". Astronomical Society of the Pacific. 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. Washington, D.C.: National Academy of Sciences. 112: 14518–21. doi:10.1073/pnas.1517557112. ISSN 1091-6490. PMC . 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. doi:10.1038/ngeo2025. Retrieved 9 December 2013.
- 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 (journal). 13 (12): 1103–24. Bibcode:2013AsBio..13.1103N. doi:10.1089/ast.2013.1030. PMC . PMID 24205812. Retrieved 15 November 2013.
- Erwin, Douglas H. (9 November 2015). "Early metazoan life: divergence, environment and ecology". Phil. Trans. R. Soc. B. 370 (20150036). doi:10.1098/rstb.2015.0036. Retrieved 7 January 2016.
- Cosmos: A Spacetime Odyssey (@35min)