The true scale of time
Earth’s history in one year
4.54 billion years
Imagine Earth forming on January 1. The moment you read these words is the very end of December 31. Scroll to discover when everything else happened.
How do you read Earth’s year?
Every event has two dates: its real age and its place in a model year. Dots on the timeline preserve time proportions. As we approach the present, clearly labelled sections zoom into the end of the same year.
We use 4.54 billion years and exactly 365 days. Historical dates use 2026 as their reference year. The calendar makes proportions visible, but does not make dating more precise. “Around December 13” still corresponds to an approximate geological age.
The earliest known evidence of life does not pinpoint the origin of the first cell. Species and major changes emerge through processes. Each event includes sources, dating limits and an explanation of what its marker represents.
In which month of the Earth year does Homo sapiens appear?
Earth's entire history fits into a model year. Choose the right part of the calendar.
Model and dating
January 1 marks Earth's formation; the end of December 31 represents 2026. We calculate the position for “about 300 thousand years ago” in a model of 4.54 billion years and 365 days. Calendar precision belongs to the model, not the scientific dating.
Scroll down. Tap an event to explore its details.
A dot marks a date. A band shows duration; a dashed mark shows uncertainty. A label may be offset from its date.
January 1 to the end of December 31
Earth’s whole year
One day in this year represents about 12.44 million real years.
- Hadean
- Archean
- Proterozoic
- Phanerozoic
Geologic timescale Eons
The axis colour shows a unit of time, named beside each event. Eons contain eras, eras contain periods, and periods contain epochs. Zooming reveals finer divisions. Numerical boundaries are approximate; colours are chosen for this site.
- Hadean4.54 billion years ago → 4.031 billion years agoShown from Earth’s formation 4.54 billion years ago; the ICS chart begins 4.567 billion years ago. End: ± 3 million years.
- Archean4.031 billion years ago → 2.5 billion years agoBeginning: ± 3 million years.
- Proterozoic2.5 billion years ago → 538.8 million years agoEnd: ± 0.6 million years.
- Phanerozoic538.8 million years ago → presentBeginning: ± 0.6 million years.
- Paleozoic538.8 million years ago → 251.902 million years ago
- Mesozoic251.902 million years ago → 66 million years ago
- Cenozoic66 million years ago → present
Keep scrolling to zoom into the end of the same year.
Zoom in: the final 61 days of the year
November and December
This is the end of the same year, seen again in more detail. Snowball Earth and the diversification of life come into view.
Geologic timescale Periods
The axis colour shows a unit of time, named beside each event. Eons contain eras, eras contain periods, and periods contain epochs. Zooming reveals finer divisions. Numerical boundaries are approximate; colours are chosen for this site.
- TonianProterozoic1 billion years ago → 720 million years ago
- CryogenianProterozoic720 million years ago → 635 million years ago
- EdiacaranProterozoic635 million years ago → 538.8 million years agoEnd: ± 0.6 million years.
- CambrianPaleozoic538.8 million years ago → 486.85 million years agoBeginning: ± 0.6 million years. End: ± 1.5 million years.
- OrdovicianPaleozoic486.85 million years ago → 443.1 million years agoBeginning: ± 1.5 million years. End: ± 0.9 million years.
- SilurianPaleozoic443.1 million years ago → 419.62 million years agoBeginning: ± 0.9 million years. End: ± 1.36 million years.
- DevonianPaleozoic419.62 million years ago → 358.86 million years agoBeginning: ± 1.36 million years. End: ± 0.19 million years.
- CarboniferousPaleozoic358.86 million years ago → 298.9 million years agoBeginning: ± 0.19 million years. End: ± 0.15 million years.
- PermianPaleozoic298.9 million years ago → 251.902 million years agoBeginning: ± 0.15 million years. End: ± 0.024 million years.
- TriassicMesozoic251.902 million years ago → 201.4 million years agoBeginning: ± 0.024 million years. End: ± 0.2 million years.
- JurassicMesozoic201.4 million years ago → 143.1 million years agoBeginning: ± 0.2 million years. End: ± 0.6 million years.
- CretaceousMesozoic143.1 million years ago → 66 million years agoBeginning: ± 0.6 million years.
- PaleogeneCenozoic66 million years ago → 23.04 million years ago
- NeogeneCenozoic23.04 million years ago → 2.58 million years ago
- QuaternaryCenozoic2.58 million years ago → present
Keep scrolling to zoom into the end of the same year.
Zoom in: the final month
December
Early dinosaurs appear around the middle of December. Human history comes later still.
Geologic timescale Periods
The axis colour shows a unit of time, named beside each event. Eons contain eras, eras contain periods, and periods contain epochs. Zooming reveals finer divisions. Numerical boundaries are approximate; colours are chosen for this site.
- DevonianPaleozoic419.62 million years ago → 358.86 million years agoBeginning: ± 1.36 million years. End: ± 0.19 million years.
- CarboniferousPaleozoic358.86 million years ago → 298.9 million years agoBeginning: ± 0.19 million years. End: ± 0.15 million years.
- PermianPaleozoic298.9 million years ago → 251.902 million years agoBeginning: ± 0.15 million years. End: ± 0.024 million years.
- TriassicMesozoic251.902 million years ago → 201.4 million years agoBeginning: ± 0.024 million years. End: ± 0.2 million years.
- JurassicMesozoic201.4 million years ago → 143.1 million years agoBeginning: ± 0.2 million years. End: ± 0.6 million years.
- CretaceousMesozoic143.1 million years ago → 66 million years agoBeginning: ± 0.6 million years.
- PaleogeneCenozoic66 million years ago → 23.04 million years ago
- NeogeneCenozoic23.04 million years ago → 2.58 million years ago
- QuaternaryCenozoic2.58 million years ago → present
Keep scrolling to zoom into the end of the same year.
Zoom in: the final 24 hours
December 31
One hour represents about 518,000 years. Our species will appear late in the evening.
Geologic timescale Epochs
The axis colour shows a unit of time, named beside each event. Eons contain eras, eras contain periods, and periods contain epochs. Zooming reveals finer divisions. Numerical boundaries are approximate; colours are chosen for this site.
- MioceneNeogene23.04 million years ago → 5.333 million years ago
- PlioceneNeogene5.333 million years ago → 2.58 million years ago
- PleistoceneQuaternary2.58 million years ago → 11.726 thousand years agoHolocene boundary: 11,700 years before 2000, converted to the 2026 reference.
- HoloceneQuaternary11.726 thousand years ago → presentHolocene boundary: 11,700 years before 2000, converted to the 2026 reference.
Keep scrolling to zoom into the end of the same year.
December 31, from 23:00 to midnight
The final hour
Neanderthals and Homo sapiens overlapped in time. Short intervals now become visible.
Geologic timescale Epochs
The axis colour shows a unit of time, named beside each event. Eons contain eras, eras contain periods, and periods contain epochs. Zooming reveals finer divisions. Numerical boundaries are approximate; colours are chosen for this site.
- PleistoceneQuaternary2.58 million years ago → 11.726 thousand years agoHolocene boundary: 11,700 years before 2000, converted to the 2026 reference.
- HoloceneQuaternary11.726 thousand years ago → presentHolocene boundary: 11,700 years before 2000, converted to the 2026 reference.
Keep scrolling to zoom into the end of the same year.
December 31, from 23:55 to midnight
The final five minutes
This interval includes the end of the Last Glacial Maximum, the rise of farming and writing.
Geologic timescale Epochs
The axis colour shows a unit of time, named beside each event. Eons contain eras, eras contain periods, and periods contain epochs. Zooming reveals finer divisions. Numerical boundaries are approximate; colours are chosen for this site.
- PleistoceneQuaternary2.58 million years ago → 11.726 thousand years agoHolocene boundary: 11,700 years before 2000, converted to the 2026 reference.
- HoloceneQuaternary11.726 thousand years ago → presentHolocene boundary: 11,700 years before 2000, converted to the 2026 reference.
Keep scrolling to zoom into the end of the same year.
Just before the end of December 31
The final second
One second represents about 144 years. Aviation, antibiotics, spaceflight and the Web fit into this interval.
Geologic timescale Epochs
The axis colour shows a unit of time, named beside each event. Eons contain eras, eras contain periods, and periods contain epochs. Zooming reveals finer divisions. Numerical boundaries are approximate; colours are chosen for this site.
- HoloceneQuaternary11.726 thousand years ago → presentHolocene boundary: 11,700 years before 2000, converted to the 2026 reference.
The end of December 31. The moment you read these words.
Take a closer look
Three stories help you read the proportions and understand what these dates actually tell us.
How recent are humans?
Homo sapiens against 4.54 billion years of Earth history. Compare the age of our species, agriculture and writing on a one-year scale.
Read the storyHow to read Earth history in one year
How can 4.54 billion years fit into one year without losing their proportions? Understand Earth's calendar, timeline zooms and approximate dates.
Read the storyDinosaurs did not all live together
Stegosaurus and Tyrannosaurus were separated by tens of millions of years. Find their places in December of Earth's model year.
Read the storyHow good is your sense of time?
Ten questions about life, climate, people and technology. Every answer reveals the real dates and their place in Earth’s year.
Play the Earth year quizQuestions about Earth’s history
About 4.54 billion years. This estimated age is supported by evidence including radiometric dating. In our model, Earth’s formation marks the start of January 1.
The entire history of Homo sapiens represents about 0.0066 percent of Earth’s history. On a single scale spanning billions of years, people and modern inventions would be almost invisible. Each zoom has its own clearly labelled range, with distances proportional to time within it.
No. They are calculations within a model year of 365 days. Real ages, dating ranges and sources appear alongside them. A time of day in Earth’s year does not mean we can date the origin of a species to the nearest minute.
No. Non-avian dinosaurs disappeared in the extinction around 66 million years ago. Birds survived and are dinosaurs. The timeline therefore distinguishes early dinosaurs, individual genera and the extinction of non-avian dinosaurs.
Earth’s history is divided into the Hadean, Archean, Proterozoic and Phanerozoic eons. The Phanerozoic contains the Paleozoic, Mesozoic and Cenozoic eras. These are different ranks: eons contain eras, eras contain periods, and periods contain epochs. The timeline colours and legend help distinguish them.
They were five major biodiversity crises during the Phanerozoic: the end-Ordovician, Late Devonian, end-Permian, end-Triassic and end-Cretaceous extinctions. Each has a separate marker on the timeline. The Late Devonian involved several crises, not one continuous extinction.
We do not know their exact starting dates. The timeline shows early evidence of life about 3.5 billion years ago and preserved structures of oxygenic photosynthesis about 1.75 billion years ago. Those structures show it existed then, but it began earlier: atmospheric oxygen was already rising about 2.4 billion years ago.