Cosmic Calendar

A graphical view of the Cosmic Calendar for presentations, featuring the months of the year, days of December, and the final minute.

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 at 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:


Date Gya Event
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[4]
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

Date Gya Event
14 Sep 4.1 "Remains of biotic life" found in 4.1 billion-year-old rocks in Western Australia.[5][6]
21 Sep 3.8 First Life (Prokaryotes)[7][8][9]
30 Sep 3.4 Photosynthesis
29 Oct 2.4 Oxygenation of Atmosphere
9 Nov 2 Complex Cells (Eukaryotes)
5 Dec 0.8 First Multicellular Life[10]
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
22 Dec 0.36 Amphibians
23 Dec 0.3 Reptiles
24 Dec 0.25 Permian-Triassic Extinction Event, 90% of Species Die Out
25 Dec 0.23 Dinosaurs
26 Dec 0.2 Mammals
27 Dec 0.15 Birds
28 Dec 0.13 Flowers
30 Dec, 06:24 0.065 Cretaceous–Paleogene extinction event, Non-avian Dinosaurs Die Out[11]

Human evolution

Date / time mya Event
30 Dec 65 Primates
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

History begins

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.

See also

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


  1. Therese Puyau Blanchard (1995). "The Universe At Your Fingertips Activity: Cosmic Calendar". Astronomical Society of the Pacific. 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. doi:10.1073/pnas.1517557112. ISSN 1091-6490. PMC 4664351Freely accessible. 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. 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 (journal). 13 (12): 1103–24. Bibcode:2013AsBio..13.1103N. doi:10.1089/ast.2013.1030. PMC 3870916Freely accessible. 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. Retrieved 7 January 2016.
  11. Cosmos: A Spacetime Odyssey (@35min)

External links

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