13.7 billion years ago - The Big Bang: beginning of the universe as we know it!
13.3 - 13.7 billion years ago - The Dark Ages, after the formation of hydrogen and before the first stars.
13.3 billion years ago - Reionization: the first stars heat and ionize hydrogen gas.
4.55 billion years ago - Formation of the Solar System.
4.5 billion years ago - Formation of the Moon: according to the Giant Impact Hypothesis, this happened when Theia collided with proto-Earth.
4.45 billion years ago - Formation of Earth complete; storm of asteroid impacts.
4 billion years ago - First life on Earth.
3.8 - 4 billion years ago - The Late Heavy Bombardment: a period during which the Earth, Moon, Venus and Mars were subjected to many asteroid impacts, after a relatively calm period of several million years.
3 billion years ago - Formation of the first known continent, Ur.
2.4 billion years ago - The Great Oxidation Event: the Earth's atmosphere gets oxygen.
1.6 billion years ago - First blue-green algae.
1.3 billion years ago - First plants.
1 billion years ago - Formation of the supercontinent Rodinia
800 million years ago - The supercontinent Rodinia begins to break up.
630-850 million years ago - The Cryogenian Period, also known as Snowball Earth - the worst ice age in the Earth's history.
670 million years ago - First animals.
440 million years ago - The Ordovician-Silurian extinction. Most marine species died out.
415 million years ago - The Old Red Sandstone Continent, also known as Laurussia, is formed by the collision of Baltica and Laurentia at the beginning of the Devonian.
395 million years ago - First insects on land.
365 million years ago - The Late Devonian extinction. 70% of marine species died out! First amphibians, trees.
313 million years ago - First reptiles.
250 million years ago - The Permian-Triassic extinction. 90% of all species died out! Formation of the supercontinent Pangaea, with surrounding ocean Panthalassa.
235 million years ago - First dinosaurs, flowers.
205 million years ago - The Triassic-Jurassic extinction. End of large amphibians and many reptiles.
200 million years ago - Pangaea began to split into separate continents: Gondwana to the south and Laurasia to the north, separated by the Tethys Sea.
150 million years ago - First birds.
114 million years ago - First modern mammals. World begins to cool.
67 million years ago - Asteroid hit Mexico, causing the Cretaceous-Tertiary extinction. End of dinosaurs. 50% of all species died out! Intensification of world cooling trend.
50 million years ago - India begins to collide with Asia, eventually forming the Himalayas.
34 million years ago - Gondwanaland finishes breaking up, with Australia and South America separating from Antarctica.
24 million years ago - Cooling trend causes the formation of grasslands; Antarctica becomes covered with ice.
21 million years ago - Apes split off from other monkeys.
5 million years ago - Humans split off from other apes (gorillas and chimpanzees).
3.9 million years ago - First known Australopithecus afarensis.
3 million years - Cooling trend causes year-round ice to form at the North Pole.
2.5 million years ago - First Homo habilis. Beginning of a period of repeated glaciation (loosely speaking, "ice ages").
1.9 million years ago - First Homo erectus.
1.4 million years ago - First firemaking by humans.
620,000 years ago - Beginning of the Cromerian interglacial.
450,000 years ago - Beginning of the 3rd most recent glacial period: the Kansan glaciation, during which ice sheets reached their maximum extent in the Pleistocene, down to Kansas and Slovakia.
380,000 years ago - Beginning of the Hoxnian interglacial.
350,000 years ago - First Homo neanderthalensis.
250,000 years ago - First Homo sapiens.
200,000 years ago - Beginning of the 2nd most recent glacial period: the Wolstonian glaciation.
125,000 years ago - Beginning of the Eemian interglacial.
100,000 years ago - Homo sapiens arrives in the Middle East.
70,000 years ago - Beginning of the most recent glacial period: the Wisconsin glaciation.
50,000 years ago - Homo sapien arrives in central Asia.
35,000 years ago - Invention of the calendar, extinction of Homo neanderthalensis. Homo sapiens arrives in Europe.
32,000 years ago - Oldest known cave paintings.
21,000 years ago - Last glacial maximum: ice sheets down to the Great Lakes, the mouth of the Rhine, and covering the British Isles.
18,000 years ago - Cultivation of plants, herding of animals. Homo sapiens arrives in the Americas.
12,700 - 11,500 years ago - the Younger Dryas.
10,300 years ago - End of the most recent glacial period: the Wisconsin glaciation.
8,800 years ago - The first cities.
7,600 years ago - Sahara desert starts forming in northern Africa.
5,500 years ago - Invention of the wheel, writing.
540 years ago - Invention of the printing press.
180 years ago - Fossil fuel revolution: coal, trains.
130 years ago - Invention of the telephone.
60 years ago - Invention of the computer.