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.
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 1977 book The Dragons of Edenand on his 1980 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 hand”.
A similar analogy used to visualize the geologic time scale and the history of life on Earth is the Geologic Calendar
Cosmology
| Date | Gya (billion years ago) | 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 |
| 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 (billion years ago) | Event |
|---|---|---|
| 14 Sep | 4.1 | First known remains of biotic life (discovered in 4.1 billion-year-old rocks in Western Australia). |
| 21 Sep | 3.8 | First Life (Prokaryotes) |
| 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 |
| 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; Ordovician–Silurian extinction events |
| 21 Dec | 0.4 | Insects and seeds |
| 22 Dec | 0.36 | Amphibians; Late Devonian extinction |
| 23 Dec | 0.3 | Reptiles |
| 24 Dec | 0.25 | Permian–Triassic extinction event; 57% of all biological families and 83% of all genera die |
| 25 Dec | 0.23 | Dinosaurs |
| 26 Dec | 0.2 | Mammals; Triassic–Jurassic extinction event |
| 27 Dec | 0.15 | Birds (avian dinosaurs) |
| 28 Dec | 0.13 | Flowers |
| 30 Dec, 06:24 | 0.065 | Cretaceous–Paleogene extinction event, non-avian dinosaurs die out |
Human evolution
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| Date / time | Mya (million years ago) | 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
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| Date / time | kya (thousand years ago) | Event |
|---|---|---|
| 31 Dec, 23:59:33 | 12.0 | End of the last Ice Age |
| 31 Dec, 23:59:41 | 8.3 | Flooding of Doggerland |
| 31 Dec, 23:59:46 | 6.0 | Chalcolithic |
| 31 Dec, 23:59:47 | 5.5 | Early Bronze Age; Proto-writing; Building of Stonehenge Cursus |
| 31 Dec, 23:59:48 | 5.0 | First Dynasty of Egypt, Early Dynastic period in Sumer, beginning of Indus Valley Civilisation |
| 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; Minoan eruption |
| 31 Dec, 23:59:53 | 3.0 | Iron Age; beginning of classical antiquity |
| 31 Dec, 23:59:54 | 2.5 | Buddha, Mahavira, Zoroaster, 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, Gupta Empire |
| 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 |
| 31 Dec, 23:59:59 | 0.5 | Modern History; the last 437.5 years before present. |
Future
Future of the Earth and the Solar System (“Year 2”)
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| Date / time | kyr(Thousand years), myr (Million years), and Byr (billion years) | Event |
|---|---|---|
| 1 Jan, 00:00:01 | 0.5 Kyr | Anthropocene Epoch |
| 1 Jan, 00:00:23 | 10.0 Kyr | Antares explodes into a supernova |
| 1 Jan, 00:00:50 | 20.0 Kyr | Chernobyl becomes safe |
| 1 Jan, 00:00:57 | 20.0 Kyr | The Arecibo message reaches the M13 cluster |
| 1 Jan, 00:01:54 | 50.0 Kyr | Niagara Falls erodes away |
| 1 Jan, 00:03:48 | 100.0 Kyr | Proper motion makes all constellations unrecognizable |
| 1 Jan, 00:11:24 | 300.0 Kyr | WR 104 explodes |
| 1 Jan, 00:19:02 | 500.0 Kyr | Earth likely hit by 1 km asteroid |
| 1 Jan, 00:38:05 | 1.0 Myr | Pyramids of Giza erode away |
| 1 Jan, 04:34:17 | 7.2 Myr | Mount Rushmore erodes away |
| 1 Jan, 16:30 | 20.00 Myr | Eastern Africa splits apart |
| 2 Jan | 50.00 Myr | Mediterranean Sea closes up due to Europe and Africa colliding |
| 3 Jan | 100.00 Myr | Saturn loses its rings |
| 5 Jan | 180.00 Myr | Earth’s day becomes one hour longer |
| 7 Jan | 240.00 Myr | Solar System completes one galactic year |
| 8 Jan | 250.00 Myr | Formation of possible new supercontinent |
| 16 Jan | 600.00 Myr | Solar eclipses no longer possible |
| 17 Jan | 700.00 Myr | Atmospheric CO2 levels too low for photosynthesis, all complex life die |
| 8 Feb | 1.0 Byr | Earth’s oceans evaporate away |
| 1 Mar | 2.0 Byr | All life on Earth dies |
| 18 Mar | 3.0 Byr | Milky Way-Andromeda collision |
| 9 Apr | 4.0 Byr | Sun expands into a red giant |
| 16 Apr | 4.0 Byr | Global surface temperatures reach 1330 deg C, hot enough to melt lead |
| 28 Jul | 7.9 Byr | Sun destroys the Earth |
| 12 Aug | 8.0 Byr | Sun becomes a white dwarf |
| 31 Dec | 12.0 Byr | Solar System ceases to exist |
Future of the Universe (“Year 3” and beyond)
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| Date / time | Byr (billion years) and above | Event |
|---|---|---|
| Year 8, 1 Apr | 100.0 | Galaxies disappear beyond light horizon |
| Year 7247, 13 Dec | 100 trillion | Star formation ends |
| Year 72,479, 11 Jul | 1 quadrillion | Sun cools down to -268 deg C |
| Year 7.94×1035 | 3×1043 | Black Hole Era |
| Year 4.54×1098 | 1.7×1098 | Last black holes evaporate |
| Year 10100 | Dark Era begins, Heat death of the universe | |
| Year 101500 | Iron Stars form, assuming protons do not decay | |
| Year 101050 | Possible Boltzmann brain appears | |
| Year 101076 | Last black holes evaporate | |
| Year 1010120 | Final entropy state, Dark Era begins, Heat death of the universe | |
| Year 10101056 | Possible new Big Bang occurs |