All of time in a single year
The cosmic calendar squeezes the universe's 13.8-billion-year history into one calendar year: the Big Bang on 1 January, today at midnight on 31 December. On this scale a day is 37.8 million years and a second is about 437 years.
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On this calendar
- 1 day ≈ 37.8 million years
- 1 hour ≈ 1.6 million years
- 1 second ≈ 437 years
Events in January
- The Big BangJanuary 1, 00:00:0013.8 billion years ago
- Quarks combineJanuary 1, 00:00:0013.8 billion years ago
- The first atomic nucleiJanuary 1, 00:00:0013.8 billion years ago
- The first atoms and the first lightJanuary 1, 00:00:0013.8 billion years ago
- The first stars igniteJanuary 4, 23:13:0213.65 billion years ago
- The Milky Way takes shapeJanuary 22, 03:49:33About 13 billion years ago
Every event on the cosmic calendar
| Event | Real time | Cosmic date |
|---|---|---|
| The Big Bang | 13.8 billion years ago | January 1, 00:00:00 |
| Quarks combine | 13.8 billion years ago | January 1, 00:00:00 |
| The first atomic nuclei | 13.8 billion years ago | January 1, 00:00:00 |
| The first atoms and the first light | 13.8 billion years ago | January 1, 00:00:00 |
| The first stars ignite | 13.65 billion years ago | January 4, 23:13:02 |
| The Milky Way takes shape | About 13 billion years ago | January 22, 03:49:33 |
| Stars die and scatter elements | Over billions of years, again and again | April 11, 12:10:26 |
| The Sun is born | 4.6 billion years ago | September 1, 08:00:00 |
| Earth forms | 4.54 billion years ago | September 2, 22:05:13 |
| The birth of the Moon | 4.5 billion years ago | September 3, 23:28:41 |
| The first oceans | 4.4 billion years ago | September 6, 14:57:23 |
| The first living things | At least 3.5 billion years ago | September 30, 10:15:39 |
| The Great Oxidation | 2.4 billion years ago | October 29, 12:31:18 |
| Iron ore deposits form | Mostly 2.5–1.8 billion years ago | November 3, 19:28:41 |
| Complex cells | About 2–1.6 billion years ago | November 14, 09:23:28 |
| Snowball Earth | 720–635 million years ago | December 13, 11:39:07 |
| The first large organisms | 575 million years ago | December 16, 19:00:00 |
| The Cambrian explosion | 538 million years ago | December 17, 18:29:13 |
| Plants move onto land | 470 million years ago | December 19, 13:39:07 |
| From water to land | 375 million years ago | December 22, 01:57:23 |
| The coal forests | 360–300 million years ago | December 23, 06:31:18 |
| The Great Dying | 252 million years ago | December 25, 08:02:05 |
| Dinosaurs appear | 230 million years ago | December 25, 22:00:00 |
| The first mammals | 200 million years ago | December 26, 17:02:36 |
| Birds: living dinosaurs | 150 million years ago | December 28, 00:46:57 |
| The asteroid strikes | 66 million years ago | December 30, 06:06:15 |
| The first primates | 55 million years ago | December 30, 13:05:13 |
| Our path splits from chimpanzees | 6–7 million years ago | December 31, 19:33:23 |
| On two feet: Lucy | 3.2 million years ago | December 31, 21:58:07 |
| Fire and travel: Homo erectus | 1.9 million years ago | December 31, 22:47:38 |
| Homo sapiens: us | 300,000 years ago | December 31, 23:48:34 |
| Göbekli Tepe | 11,600 years ago | December 31, 23:59:33 |
| Farming begins | About 11,000 years ago | December 31, 23:59:34 |
| The first metal: copper | About 7,000 years ago | December 31, 23:59:44 |
| Writing | 5,200 years ago | December 31, 23:59:48 |
| The Iron Age | Around 1200 BCE | December 31, 23:59:52 |
| Mass-produced steel | 1856 | December 31, 23:59:59 |
| Inside the atom | 1911 | December 31, 23:59:59 |
| Today: you | Today | December 31, 24:00:00 |
Frequently asked questions
How old is the universe?
About 13.8 billion years. The figure comes from measurements of the first light released 380,000 years after the Big Bang (the cosmic microwave background).
When did the Sun and Earth form?
The Sun formed about 4.6 billion years ago and Earth about 4.54 billion years ago. These ages are calculated from the known decay rates of radioactive elements in meteorites and rocks.
Did humans live alongside dinosaurs?
No. The non-bird dinosaurs died out 66 million years ago, while Homo sapiens appeared about 300,000 years ago, more than 65 million years later. But our ancestors, small mammals, did live alongside the dinosaurs.