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.

This graphic shows in a spiral a summary of notable events from the Big Bang to the present day. Every billion years (Ga) is represented in 90 degrees of rotation of the spiral.
A graphical view of the Cosmic Calendar, featuring the months of the year, days of December, and the final minute.

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 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 is scaled to the size of a football field, then "all of human history would occupy an area the size of [his] hand".[3]

A similar analogy used to visualize the geologic time scale and the history of life on Earth is the Geologic Calendar


DateGya (billion years ago)Event
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

DateGya (billion years ago)Event
14 Sep4.1First known remains of biotic life (discovered 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; Ordovician–Silurian extinction events
21 Dec0.4Insects and seeds
22 Dec0.36Amphibians; Late Devonian extinction
23 Dec0.3Reptiles
24 Dec0.25Permian–Triassic extinction event; 57% of all biological families and 83% of all genera die
25 Dec0.23Dinosaurs
26 Dec0.2Mammals; Triassic–Jurassic extinction event
27 Dec0.15Birds (avian dinosaurs)
28 Dec0.13Flowers
30 Dec, 06:240.065Cretaceous–Paleogene extinction event, non-avian dinosaurs die out[11]

Human evolution

Date / timeMya (million years ago)Event
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 / timekya (thousand years ago)Event
31 Dec, 23:59:3312.0End of the last 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, Achaemenid Empire, 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
31 Dec, 23:59:59 0.5 Modern History; the last 437.5 years before present.


Future of the Earth and the Solar System ("Year 2")

Date / timekyr(Thousand years), myr (Million years), and Byr (billion years)Event
1 Jan, 00:00:010.5 KyrAnthropocene Epoch
1 Jan, 00:00:2310.0 KyrAntares explodes into a supernova
1 Jan, 00:00:5020.0 KyrChernobyl becomes safe
1 Jan, 00:00:5720.0 KyrThe Arecibo message reaches the M13 cluster
1 Jan, 00:01:5450.0 KyrNiagara Falls erodes away
1 Jan, 00:03:48100.0 KyrProper motion makes all constellations unrecognizable
1 Jan, 00:11:24300.0 KyrWR 104 explodes
1 Jan, 00:19:02500.0 KyrEarth likely hit by 1 km asteroid
1 Jan, 00:38:051.0 MyrPyramids of Giza erode away
1 Jan, 04:34:177.2 MyrMount Rushmore erodes away
1 Jan, 16:3020.00 MyrEastern Africa splits apart
2 Jan50.00 MyrMediterranean Sea closes up due to Europe and Africa colliding
3 Jan100.00 MyrSaturn loses its rings
5 Jan180.00 MyrEarth's day becomes one hour longer
7 Jan240.00 MyrSolar System completes one galactic year
8 Jan250.00 MyrFormation of possible new supercontinent
16 Jan600.00 MyrSolar eclipses no longer possible
17 Jan700.00 MyrAtmospheric CO2 levels too low for photosynthesis, all complex life die
8 Feb1.0 ByrEarth's oceans evaporate away
1 Mar2.0 ByrAll life on Earth dies
18 Mar3.0 ByrMilky Way-Andromeda collision
9 Apr4.0 ByrSun expands into a red giant
16 Apr4.0 ByrGlobal surface temperatures reach 1330 deg C, hot enough to melt lead
28 Jul7.9 ByrSun destroys the Earth
12 Aug8.0 ByrSun becomes a white dwarf
31 Dec12.0 ByrSolar System ceases to exist

Future of the Universe ("Year 3" and beyond)

Date / timeByr (billion years) and aboveEvent
Year 8, 1 Apr100.0Galaxies disappear beyond light horizon
Year 7247, 13 Dec100 trillionStar formation ends
Year 72,479, 11 Jul1 quadrillionSun cools down to -268 deg C
Year 7.94×10353×1043Black Hole Era
Year 4.54×10981.7×1098Last black holes evaporate
Year 10100Dark Era begins, Heat death of the universe
Year 101500Iron Stars form, assuming protons do not decay
Year 101050Possible Boltzmann brain appears
Year 101076Last black holes evaporate
Year 1010120Final entropy state, Dark Era begins, Heat death of the universe
Year 10101056Possible new Big Bang occurs

See also

  • History of Earth  The development of planet Earth from its formation to the present day


  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. 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.
  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.
  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.
  10. 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.
  11. "Cosmos: A Spacetime Odyssey (@35min)". Archived from the original on 2014-03-11. Retrieved 2014-03-11.