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Cosmic Calendar

Last updated: 2025-08-06 22:35:41

Cosmic Calendar
A graphical view of the Cosmic Calendar, featuring the months of the year, days of December, the final minute, and the final second
Video of the calendar

The Cosmic Calendar is a method to visualize the chronology of the universe, scaling its currently understood age of 13.787 billion years to a single year in order to help intuit it for pedagogical purposes in science education or popular science. A similar analogy used to visualize the geologic time scale and the history of life on Earth is the Geologic Calendar.

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 438 years per cosmic second, 1.58 million years per cosmic hour, and 37.8 million years per cosmic day.

The Solar System materialized in Cosmic September. The Phanerozoic corresponds only to the latter half of December, with the Cenozoic only happening on the penultimate day on the Calendar. The Quaternary only applies to the last four hours on the final Cosmic Day, with the Holocene only applying to the final 23 Cosmic Seconds. On the other hand, relic radiation is dated at the first fifteen minutes of the very first Cosmic Day; even if we stretch the Cosmic Calendar to 100 years, the relic radiation would still happen just after the start of the second Cosmic Day.

The concept was popularized by Carl Sagan in his 1977 book The Dragons of Eden and on his 1980 television series Cosmos.[2] Sagan goes on to extend the comparison in terms of surface area, explaining that if the Cosmic Calendar were 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 Calendar was reused in the 2014 series, Cosmos: A Spacetime Odyssey.[4]

Cosmology

Sources[5][6]

DateGya (billion years ago)Event
1 January, 0:0013.787The Big Bang[7]
1 January, 0:14 13.787 The cosmic background radiation. Would have been last emitted 14 minutes after midnight
1 January, 0:30 13.787 First atoms
19 January 13 GRB 090423, Oldest known Gamma Ray Burst
26 January 12.85 First galaxies form[8]
1 March11Milky Way Galaxy formed
13 May8.8Milky Way Galaxy disk formed
9 September4.57Formation of the Solar System
14 September4.5Formation of the Earth and The Moon

Date in year calculated from formula

T(days) = 365 days * ( 1- T_Gya/13.787)

Evolution of life on Earth

DateGya (billion years ago)Event
14 September4.1First known remains of biotic life (discovered in 4.1 billion-year-old rocks in Western Australia).[9][10]
21 September3.8First Life (Prokaryotes)[11][12][13]
30 September3.4Photosynthesis
29 October2.4Oxygenation of atmosphere
9 November2Complex cells (Eukaryotes)
5 December0.8First multicellular life[14]
7 December0.67Simple animals
14 December0.55Arthropods (ancestors of insects, arachnids)
17 December0.53Fish and Proto-amphibians
18 December 0.518 Vertebrates
19 December0.45Land plants; Ordovician–Silurian extinction events
20 December 0.4 Jawed fish
21 December0.35Insects and seeds
22 December0.33Amphibians; Late Devonian extinction
23 December0.3Reptiles
24 December0.25Permian–Triassic extinction event; 57% of all biological families and 83% of all genera die
25 December0.23Dinosaurs
26 December0.201Mammals; Triassic–Jurassic extinction event
27 December0.072Birds (avian dinosaurs)
28 December0.13Flowers
30 December, 6:240.066Cretaceous–Paleogene extinction event, non-avian dinosaurs go extinct;[15] Primates

Human evolution

Date / timeMya (million years ago)Event
31 December, 6:0528Apes
31 December, 14:2412.3Hominids
31 December, 20:00 7 Chimpanzees and Humans split
31 December, 22:242.8Homos and stone tools
31 December, 23:440.4Domestication of fire
31 December, 23:520.2Humans
31 December, 23:550.115Beginning of most recent Glacial Period
31 December, 23:580.035Sculpture and painting
31 December, 23:59:320.012Agriculture

History begins

Date / timekya (thousand years ago)Event
31 December, 23:59:3311.7End of the last Ice Age
31 December, 23:59:418.3Flooding of Doggerland
31 December, 23:59:466Chalcolithic
31 December, 23:59:475.5Early Bronze Age; Proto-writing; Building of Stonehenge Cursus
31 December, 23:59:485First Dynasty of Egypt, Early Dynastic period in Sumer, beginning of Indus Valley civilisation
31 December, 23:59:494.5Alphabet, Akkad, wheel
31 December, 23:59:514Code of Hammurabi, Middle Kingdom of Egypt
31 December, 23:59:523.5Late Bronze Age to early Iron Age; Minoan eruption
31 December, 23:59:533Iron Age; beginning of classical antiquity
31 December, 23:59:542.5Buddha, Mahavira, Zoroaster, Confucius, Achaemenid Empire, Qin dynasty, Classical Greece, Ashokan Empire, Vedas completed, Euclidean geometry, Archimedean physics, Roman Republic
31 December, 23:59:552Ptolemaic astronomy, Roman Empire, Jesus, invention of numeral 0, Gupta Empire
31 December, 23:59:561.5Muhammad, Maya civilization, Song dynasty, Black Death, Byzantine Empire
31 December, 23:59:581Mongol Empire, Maratha Empire, Crusades, Christopher Columbus voyages to the Americas, Renaissance in Europe, Classical music to the time of Johann Sebastian Bach
31 December, 23:59:59 0.5 Modern History; the last 437.5 years before present. 7 Years War, American and French Revolutions, Airplanes, World War 1 and 2, Computers, Spaceflight, First human landing on The Moon

References

  1. ↑ Blanchard, Therese Puyau (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. ↑ Witt, Steven (December 2024). "Libraries at the intersection of history and the present". IFLA Journal. 50 (4): 691–695. doi:10.1177/03400352241299307. ISSN 0340-0352.
  3. ↑ "The Shores of the Cosmic Ocean". Cosmos: A Personal Voyage. Episode 1. 1980-10-01. Event occurs at 51:10. Public Broadcasting Service.
  4. ↑ Zakariya, Nasser (July 2015). "Exhibiting Cosmos". Technology and Culture. 56 (3): 738–744. doi:10.1353/tech.2015.0086. ISSN 1097-3729. PMID 26387528.
  5. ↑ "Cosmic Calendar". visav.phys.uvic.ca. Retrieved 2025-02-18.
  6. ↑ "The Cosmic Calendar". www.yorku.ca. Retrieved 2025-02-18.
  7. ↑ "Planck reveals an almost perfect universe". Max-Planck-Gesellschaft. March 21, 2013. Retrieved 2020-11-17.
  8. ↑ "First Galaxies Born Sooner After Big Bang Than Thought". Space.com. 14 April 2011. Retrieved 2015-11-07.
  9. ↑ Borenstein, Seth (19 October 2015). "Hints of life on what was thought to be desolate early Earth". Excite. Yonkers, New York: Mindspark Interactive Network. Associated Press. Retrieved 2015-10-20.
  10. ↑ 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.
  11. ↑ Ohtomo, Yoko; Kakegawa, Takeshi; Ishida, Akizumi; Nagase, Toshiro; Rosing, Minik T. (8 December 2013). "Evidence for biogenic graphite in early Archaean Isua metasedimentary rocks". Nature Geoscience. 7 (1): 25–28. Bibcode:2014NatGe...7...25O. doi:10.1038/ngeo2025.
  12. ↑ Borenstein, Seth (13 November 2013). "Oldest fossil found: Meet your microbial mom". AP News. Retrieved 15 November 2013.
  13. ↑ 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.
  14. ↑ Erwin, Douglas H. (9 November 2015). "Early metazoan life: divergence, environment and ecology". Phil. Trans. R. Soc. B. 370 (20150036): 20150036. Bibcode:2015RSPTB.37050036E. doi:10.1098/rstb.2015.0036. PMC 4650120. PMID 26554036.
  15. ↑ "Cosmos: A Spacetime Odyssey (@35min)". Archived from the original on 2014-03-11. Retrieved 2014-03-11.

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