Cosmic Calendar

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 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.[1] 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.[2] 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".[3]

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 Jan13.8Big Bang, as seen through cosmic background radiation
14 Jan 13.1 Oldest known Gamma Ray Burst
22 Jan 12.85 First galaxies form[4]
16 Mar11Milky Way Galaxy formed
12 May8.8Milky Way Galaxy disk formed
2 Sep4.57formation of the Solar System
6 Sep4.4Oldest 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 Sep4.1First known "remains of biotic life" found in 4.1 billion-year-old rocks in Western Australia.[5][6]
21 Sep3.8First Life (Prokaryotes)[7][8][9]
30 Sep3.4Photosynthesis
29 Oct2.4Oxygenation of Atmosphere
9 Nov2Complex Cells (Eukaryotes)
5 Dec0.8First Multicellular Life[10]
7 Dec0.67Simple Animals
14 Dec0.55Arthropods (ancestors of insects, arachnids)
17 Dec0.5Fish and Proto-amphibians
20 Dec0.45Land Plants
21 Dec0.4Insects and Seeds
22 Dec0.36Amphibians
23 Dec0.3Reptiles
24 Dec0.25Permian-Triassic Extinction Event, 90% of Species Die Out
25 Dec0.23Dinosaurs
26 Dec0.2Mammals
27 Dec0.15Birds
28 Dec0.13Flowers
30 Dec, 06:240.065Cretaceous–Paleogene extinction event, Non-avian Dinosaurs Die Out[11]

Human evolution

Date / timemyaEvent
30 Dec65Primates
31 Dec, 06:0515Apes
31 Dec, 14:2412.3Hominids
31 Dec, 22:242.5Primitive Humans and Stone Tools
31 Dec, 23:440.4Domestication of Fire
31 Dec, 23:520.2Anatomically Modern Humans
31 Dec, 23:550.11Beginning of Most Recent Glacial Period
31 Dec, 23:580.035Sculpture and Painting
31 Dec, 23:59:320.012Agriculture

History begins

Date / timekyaEvent
31 Dec, 23:59:3312.0End of the Ice Age
31 Dec, 23:59:418.3Flooding of Doggerland
31 Dec, 23:59:466.0Chalcolithic
31 Dec, 23:59:475.5Early Bronze Age; Proto-writing; Building of Stonehenge Cursus
31 Dec, 23:59:485.0First Dynasty of Egypt, Early Dynastic Period in Sumer, Beginning of Indus Valley Civilisation
31 Dec, 23:59:494.5Alphabet, Akkadian Empire, Wheel
31 Dec, 23:59:514.0Code of Hammurabi, Middle Kingdom of Egypt
31 Dec, 23:59:523.5Late Bronze Age to Early Iron Age; Minoan eruption
31 Dec, 23:59:533.0Iron Age; Beginning of Classical Antiquity
31 Dec, 23:59:542.5Buddha, Mahavira, Zoroaster, Confucius, Qin Dynasty, Classical Greece, Ashokan Empire, Vedas Completed, Euclidean geometry, Archimedean Physics, Roman Republic
31 Dec, 23:59:552.0Ptolemaic astronomy, Roman Empire, Christ, Invention of Numeral 0, Gupta Empire
31 Dec, 23:59:561.5Muhammad, Maya civilization, Song Dynasty, Rise of Byzantine Empire
31 Dec, 23:59:581.0Mongol 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 / timekyaEvent
31 Dec, 23:59:590.5Modern History; the last 437.5 years before present.

See also


  1. 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.
  2. Cosmos, episode 1 (1980)
  3. Episode 1: The Shores of the Cosmic Ocean (Cosmos: A Personal Voyage, Carl Sagan)
  4. "First Galaxies Born Sooner After Big Bang Than Thought". Retrieved 2015-11-07.
  5. 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.
  6. 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. 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.
  7. 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. Retrieved 9 December 2013.
  8. Borenstein, Seth (13 November 2013). "Oldest fossil found: Meet your microbial mom". AP News. Retrieved 15 November 2013.
  9. 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. Retrieved 15 November 2013.
  10. 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. PMC 4650120. Retrieved 7 January 2016.
  11. Cosmos: A Spacetime Odyssey (@35min)
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