The "Cosmic Calendar" was a device used by the astronomer Carl Sagan to show the history of the entire cosmos as one calendar year. With the Big Bang occurring at the beginning of January first and our current time as the last second of December 31st, we can arrange the entire history of the known universe into twelve months. Each month is a little over 1 billion years, each second around 400 years.
|
January (15 b yrs) |
February | March | April |
|
The Big Bang |
Milky Way Forms |
||
| May (10.1 b yrs) | June | July | August |
|
Milky Way |
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| September (4.5 b yrs) | October (3.7 b yrs) | November | December |
|
Solar System & Earth |
Origin of life on earth |
First multi-cellular organisms |
(see detail below) |
December
| Sunday | Monday | Tuesday | Wednesday | Thursday | Friday | Saturday |
| 1 (1.3 billion) | 2 | 3 | 4 | 5 | 6 | |
| oxygen atmosphere on earth | volcanism on Mars | |||||
| 7 | 8 | 9 | 10 | 11 | 12 | 13 |
| 14 | 15 | 16 (658 mill) | 17 | 18 (575 mill) | 19 (534 mill) | 20 (493 mill) |
| First worms | Ocean plankton Trilobites | First fish & vertebrates | Plants begin | |||
| 21 (452 mill) | 22 (411 mill) | 23 (370 mill) | 24 (329 mill) | 25 | 26 (247 mill) | 27 (205 mill) |
| Insects. Animals colonize land | First amphibians & winged insects | First trees & reptiles | First dinosaurs | First mammals | First birds | |
| 28 (164 mill) | 29 (123 mill) | 30 (82 mill) | 31 (41 mill) | |||
| First flowers. Dinos extinct | First primates | Giant mammals flourish | First humans (see detail) |
December 31st
9.24pm First humans walk upright
10.48pm Homo Erectus appears
11.54pm Anatomically modern humans appear
11.59.45pm Invention of writing
11.59.50pm Pyramids built in Egypt
1 second before midnight: Voyage of Christopher Columbus