Cosmic Calendar

TheCosmic Calendaris a method to visualize thechronology of the universe,scaling itscurrently understood ageof 13.8 billion years to a singleyearin order to help intuit it for pedagogical purposes inscience educationorpopular science.

In this visualization, theBig Bangtook 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 cosmic second, 1.575 million years per cosmic hour, and 37.8 million years per cosmic day.

The concept was popularized byCarl Saganin his 1977 bookThe Dragons of Edenand on his 1980 television seriesCosmos.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".

A similar analogy used to visualize thegeologic time scaleand thehistory of life on Earthis theGeologic Calendar.

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

Cosmology

Date	Gya (billion years ago)	Event
1 Jan	13.8	Big Bang,as seen throughcosmic background radiation,which would have been last emitted 14 minutes after midnight
19 Jan	13.1	Oldest knownGamma Ray Burst
26 Jan	12.85	First galaxies form
16 Mar	11	Milky Way Galaxyformed
13 May	8.8	Milky Way Galaxy diskformed
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 * ( 1- T_Gya/13.797 )

Evolution of life on Earth

Date	Gya (billion years ago)	Event
14 Sep	4.1	First known remains ofbiotic life(discovered in 4.1 billion-year-old rocks inWestern 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	Firstmulticellular life
7 Dec	0.67	Simpleanimals
14 Dec	0.55	Arthropods(ancestors of insects, arachnids)
17 Dec	0.5	Fishand Proto-amphibians
20 Dec	0.45	Land plants;Ordovician–Silurian extinction events
21 Dec	0.4	Insectsandseeds
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

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 humansandstone 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 (thousand years ago)	Event
31 Dec, 23:59:33	12.0	End of thelast Ice Age
31 Dec, 23:59:41	8.3	Flooding ofDoggerland
31 Dec, 23:59:46	6.0	Chalcolithic
31 Dec, 23:59:47	5.5	Early Bronze Age;Proto-writing;Building ofStonehenge Cursus
31 Dec, 23:59:48	5.0	First Dynasty of Egypt,Early Dynastic period in Sumer,beginning ofIndus 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 Agetoearly Iron Age;Minoan eruption
31 Dec, 23:59:53	3.0	Iron Age;beginning ofclassical antiquity
31 Dec, 23:59:54	2.5	Buddha,Mahavira,Zoroaster,Confucius,Achaemenid Empire,Qin dynasty,Classical Greece,Ashokan Empire,Vedascompleted,Euclideangeometry,Archimedeanphysics,Roman Republic
31 Dec, 23:59:55	2.0	Ptolemaicastronomy,Roman Empire,Christ,invention of numeral0,Gupta Empire
31 Dec, 23:59:56	1.5	Muhammad,Maya civilization,Song dynasty,rise ofByzantine Empire
31 Dec, 23:59:58	1.0	Mongol Empire,Maratha Empire,Crusades,Christopher Columbusvoyages to the Americas,Renaissancein Europe, Classical music to the time ofJohann Sebastian Bach
31 Dec, 23:59:59	0.5	Modern History;the last 437.5 yearsbefore present.

See also

• Geologic Calendar
• Big History– Academic discipline which examines history from the Big Bang to the present
• Detailed logarithmic timeline– Timeline of the universe, Earth, and mankind
• List of timelines
• Timeline of ancient history
• Timeline of early modern history
• Timeline of the evolutionary history of life
• Timeline of the far future– Scientific projections regarding the far future
• Timeline of human evolution
• Timeline of human prehistory
• Timelines of modern history
• Timeline of natural history
• Timeline of plant evolution– Chronological outline of major events in the development of plants
• Chronology of the universe– History and future of the universe
• Timeline of the Middle Ages– Timeline of events 5th–15th century CEPages displaying short descriptions of redirect targets
• Cosmic time– Time coordinate used in cosmology
• History of Earth– Development of planet Earth from its formation to the present day

External links

• More information on the image used for this article.
• The Cosmic Calendar in a Google Calendar format
• The Cosmic Calendar relayed in real time.