What is the Cosmic Calendar?

The Cosmic Calendar compresses the entire 13.8-billion-year history of the universe into a single calendar year, an idea popularised by Carl Sagan in 1977. On this scale the Big Bang happens at midnight on January 1st, one calendar day equals about 37.8 million real years, and one second equals 437 years. This page is an interactive, zoomable timeline: scroll to zoom from the whole year down to the final tenth of a second before midnight on December 31st, where all of recorded human history lives.

Key dates on the cosmic year

• January 1 — the Big Bang; the first atoms form 14 cosmic minutes later
• January 6 — the first stars ignite
• January 16 — the Milky Way begins to form
• September 2 — the Sun ignites and the Earth forms
• September 21 — first life appears in Earth's oceans
• December 17 — the Cambrian explosion
• December 19 — plants colonise land
• December 25 — the first dinosaurs
• December 30, before lunch — the asteroid ends the dinosaurs
• December 31, 23:48 — Homo sapiens appears
• December 31, 26 seconds to midnight — farming begins
• December 31, 12 seconds to midnight — writing is invented; recorded history begins
• December 31, 4.6 seconds to midnight — Jesus is born
• December 31, 0.04 seconds to midnight — the iPhone
• December 31, midnight — right now; an 80-year human life lasts 0.18 cosmic seconds