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. 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. 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". The Cosmic Calendar was reused in the 2014 series Cosmos: A Spacetime Odyssey.
The Cosmic Calendar is significantly mentioned in Samantha Harvey's novel Orbital.
Cosmology Sources: Date Gya (billion years ago) Event 1 January, 0:00 13.787 The Big Bang1 January, 0:1413.787The cosmic background radiation. Would have been last emitted 14 minutes after midnight1 January, 0:3013.787First atoms19 January13GRB 090423, Oldest known Gamma Ray Burst26 January12.85First galaxies form 1 March 11 Milky Way Galaxy formed 13 May 8.8 Milky Way Galaxy disk formed 9 September 4.57 Formation of the Solar System 14 September 4.5 Formation 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
Date Gya (billion years ago) Event 14 September 4.1 First known remains of biotic life (discovered in 4.1 billion-year-old rocks in Western Australia). Early edition, published online before print. 21 September 3.8 First Life (Prokaryotes) 30 September 3.4 Photosynthesis 29 October 2.4 Oxygenation of atmosphere 9 November 2 Complex cells (Eukaryotes) 5 December 0.8 First multicellular life 7 December 0.67 Simple animals 14 December 0.55 Arthropods (ancestors of insects, arachnids) 17 December 0.53 Fish and Proto-amphibians18 December0.518Vertebrates 19 December 0.45 Land plants; Ordovician–Silurian extinction events20 December0.4Jawed fish 21 December 0.35 Insects and seeds 22 December 0.33 Amphibians; Late Devonian extinction 23 December 0.3 Reptiles 24 December 0.25 Permian–Triassic extinction event; 57% of all biological families and 83% of all genera die 25 December 0.23 Dinosaurs 26 December 0.201 Mammals; Triassic–Jurassic extinction event 27 December 0.15 Birds (avian dinosaurs) 28 December 0.13 Flowers 30 December, 6:24 0.066 Cretaceous–Paleogene extinction event, non-avian dinosaurs go extinct; Primates
Human evolution
Date / time Mya (million years ago) Event 31 December, 6:05 28 Apes 31 December, 14:24 12.3 Hominids31 December, 20:007Chimpanzees and Humans split 31 December, 22:24 2.8 Homos and stone tools 31 December, 23:44 0.4 Domestication of fire 31 December, 23:52 0.2 Humans 31 December, 23:55 0.115 Beginning of most recent Glacial Period 31 December, 23:58 0.035 Sculpture and painting 31 December, 23:59:32 0.012 Agriculture
History begins
Date / time kya (thousand years ago) Event 31 December, 23:59:33 11.7 End of the last Ice Age 31 December, 23:59:41 8.3 Flooding of Doggerland 31 December, 23:59:46 6 Chalcolithic 31 December, 23:59:47 5.5 Early Bronze Age; proto-writing; building of Stonehenge Cursus 31 December, 23:59:48 5 First Dynasty of Egypt, Early Dynastic period in Sumer, beginning of Indus Valley civilisation 31 December, 23:59:49 4.5 Alphabet, Akkad, wheel 31 December, 23:59:51 4 Code of Hammurabi, Middle Kingdom of Egypt 31 December, 23:59:52 3.5 Late Bronze Age to early Iron Age; Minoan eruption 31 December, 23:59:53 3 Iron Age; beginning of classical antiquity 31 December, 23:59:54 2.5 Buddha, Mahavira, Zoroaster, Confucius, Achaemenid Empire, Qin dynasty, Classical Greece, Ashokan Empire, Vedas completed, Euclidean geometry, Archimedean physics, Roman Republic 31 December, 23:59:55 2 Ptolemaic astronomy, Roman Empire, Jesus, invention of numeral 0, Gupta Empire 31 December, 23:59:56 1.5 Muhammad, Maya civilization, Song dynasty, Black Death, Byzantine Empire 31 December, 23:59:58 1 Mongol Empire, Maratha Empire, crusades, Christopher Columbus voyages to the Americas, Renaissance in Europe, Classical music to the time of Johann Sebastian Bach31 December, 23:59:590.5Modern 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