About
About Earth, Then Us
A short account of what this project is, how the three scales work, and where every date comes from.
What this is
Earth, Then Us follows the published scientific record. Dates are approximate where the science is uncertain. The positions of the continents through deep time follow published plate reconstructions, while their surfaces, climates and colours are an artistic impression.
Three ways to feel the same history
- One day
- If all of Earth's history were a single day, humans appear in the last few seconds before midnight.
- One year
- If all of Earth's history were one year, humans appear late on the evening of December 31.
- 4.54 kilometres
- If you walked all of Earth's history as 4.54 kilometres, our species fits in the last thirty centimetres.
Sources and method
Ages and events draw on public records from NASA, the Smithsonian Institution, the US Geological Survey and the International Commission on Stratigraphy. Links marked for verification still need a confirmed reference. The modern planet is rendered from NASA Earth Observatory imagery, the Blue Marble and Black Marble collections. Ancient coastlines are reconstructed with the GPlates Web Service from the EarthByte group, using the plate model published by Merdith and colleagues in 2021.
Questions people ask
- How old is Earth?
- Earth is about 4.54 billion years old, based on radiometric dating of meteorites and Moon rock.
- How long have humans existed?
- Homo sapiens has existed for roughly 300,000 years. That is about 0.0066 percent of Earth's history, so Earth lived through more than 99.99 percent of its history before we arrived.
- When did the dinosaurs go extinct?
- The non bird dinosaurs died out about 66 million years ago, when a large asteroid struck Earth and drove a mass extinction.
- When did life first appear on Earth?
- Rocks from about 3.7 billion years ago carry marks that may be traces of life, though those claims are disputed. Clearer evidence appears by about 3.5 billion years ago. When life actually began is still an open question.
- How does human history compare to Earth's history?
- If all of Earth's history were a single day, humans would appear in the last few seconds before midnight. On a walk of 4.54 kilometres, our species fits in the final thirty centimetres.