Where does that sit in the history of the universe?
Compressed into one year, the whole of human history happens in the last two seconds of 31 December.
10,391,569 × the Big Bang
4,540,000,000 yr is earlier than 10 of the 10 references on this page.
Reference figures are measurements and are rounded; the unit conversion behind them is exact.
| Reference | Size | Yours ÷ theirs | Note |
|---|---|---|---|
| first humans | 0.00951 yr | 477,561,873,600× | |
| first dinosaurs | 7.38 yr | 614,886,533× | |
| first animals | 25.4 yr | 179,085,703× | |
| oxygen in the atmosphere | 76.1 yr | 59,695,234× | |
| first life | 117 yr | 38,721,233× | |
| the Earth forms | 144 yr | 31,556,952× | |
| the Sun forms | 146 yr | 31,145,340× | |
| Milky Way forms | 428 yr | 10,612,486× | |
| first stars | 431 yr | 10,534,453× | |
| the Big Bang | 437 yr | 10,391,569× |
Worth knowing
- The universe spent its first 380 000 years opaque. The cosmic microwave background is the flash from the moment it cleared.
- On a one-year cosmic calendar, the Earth forms in early September and all recorded history fits in the final 14 seconds.
Frequently asked
How do we know the universe is 13.8 billion years old?
Mainly from the cosmic microwave background: its temperature fluctuations encode the expansion history, which the Planck satellite measured to about 0.15% precision.
What was before the Big Bang?
The question may not be well posed — time as we can describe it begins there. Physics beyond the first 10⁻⁴³ seconds is genuinely unknown, not merely unsettled.