Cosmic Calendar Countdown

Carl Sagan’s Cosmic Calendar maps the entire history of our cosmos onto a single year.  You can follow the entire calendar here at HP.  As you imagine, things speed up considerably as the year advances.  After the Big Bang on January 1, we have to wait until May for the Milky Way to form and September for our own Sun to form.  But things get really busy in December:

Dec 5  First multicellular life 1 bya

Dec 14  Simple animals emerge 0.67 bya

Dec 14  Arthropods emerge 0.55 bya

Dec 18  Fish and proto-amphibians emerge 0.5 bya

Dec 20  Land plants emerge 0.45 bya

Dec 21  Insects and seeds emerge 0.4 bya

Dec 22  Amphibians emerge 0.36 bya

Dec 23  Reptiles and dinosaurs emerge 0.3 bya

Dec 26  Mammals emerge 0.2 bya

Dec 27  Birds emerge 0.15 bya

Dec 28  Flowers emerge 0.13 bya

Dec 30  Cretaceous-Paleogene extinction event (non-avian dinosaurs die out) 65 mya

Dec 30 Primates emerge 65 mya

Dec 31  Hominids emerge 15 mya

When December 31st arrives, we have an especially fun way to count down to the New Year with Sagan’s Cosmic Calendar.  Jon Cleland Host shares the experience with his children, calling out momentous events by the tick of a watch, as history whizzes by in the last few seconds before midnight.  Try it out!  (Skip some as you like). This is so much more fun than just sitting around waiting for the ball to start moving!

Human evolution

Date / time mya Event
31 Dec, 06:05 15 Apes
31 Dec, 14:24 6 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

Written records begin

Date / time kya Event
31 Dec, 23:59:47 5.5 First writing (marks end of prehistory and beginning of history), beginning of the Bronze Age
31 Dec, 23:59:48 5.0 First dynasty of EgyptEarly Dynastic period in SumerAstronomy
31 Dec, 23:59:49 4.5 AlphabetAkkadian EmpireWheel
31 Dec, 23:59:51 4.0 Code of HammurabiMiddle Kingdom of Egypt
31 Dec, 23:59:52 3.5 Mycenaean GreeceOlmec civilization; Iron Age in Near East, India, and Europe; founding of Carthage
31 Dec, 23:59:53 3.0 Ancient Olympic games
31 Dec, 23:59:54 2.5 BuddhaConfuciusQin DynastyClassical GreeceAshokan EmpireVedas completed, Euclidean geometry, Archimedean physics, Roman Republic
31 Dec, 23:59:55 2.0 Ptolemaic astronomy, Roman EmpireChrist, invention of numeral 0
31 Dec, 23:59:56 1.5 MuhammadMaya civilizationSong Dynasty, rise of Byzantine Empire
31 Dec, 23:59:58 1.0 Mongol EmpireCrusadesChristopher Columbus voyages to the Americas, Renaissance in Europe

The current second

Date / time kya Event
31 Dec, 23:59:59 0.5 modern science and technology, American RevolutionFrench revolutionWorld War IWorld War IIApollo Moon landing

Below is a video of Carl Sagan explaining the Cosmic Calendar.

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