The Cosmic Calendar Essay By Carl Sagans Cosmos
On this Cosmic Calendar, the Big Bang happens on January 1st at midnight, and we are at the end of the year, midnight on December 31st. Now look backwards:
Down here, the first humans made their debut around 10:30 p.m. on December 31st. And with the passing of every cosmic minute — each minute 30,000 years long — we began the arduous journey towards understanding where we live and who we are.
11:46 – only 14 minutes ago, humans have tamed fire.
11:59:20 – the evening of the last day of the cosmic year — the 11th hour, the 59th minute, the 20th second — the domestication of plants and animals began, an application of the human talent for making tools.
11:59:35 – settled agricultural communities evolved into the first cities.
We humans appear on the cosmic calendar so recently that our recorded history occupies only the last few seconds of the last minute of December 31st. In the vast ocean of time which this calendar represents, all our memories are confined to this small square.
Every person we’ve ever heard of lived somewhere in there. All those kings and battles, migrations and inventions, wars and loves. Everything in the history books happens here, in the last 10 seconds of the cosmic calendar.
The Cosmic Calendar is a method to visualize the chronology of the universe, scaling its current age of 13.8 billion years to a single year in order to help intuit it for pedagogical purposes in science education or popular science.
In this visualization, the Big Bang took place at the beginning of January 1 at midnight, and the current moment maps onto the end of December 31 just before midnight. At this scale, there are 437.5 years per second, 1.575 million years per hour, and 37.8 million years per day.
The concept was popularized by Carl Sagan in his book The Dragons of Eden (1977) and on his television series Cosmos. Sagan goes on to extend the comparison in terms of surface area, explaining that if the Cosmic Calendar is scaled to the size of a football field, then "all of human history would occupy an area the size of [his] hand".
The Cosmic Year
The Cosmic Calendar shows the time-scale relationship of the universe and all events on Earth as plotted along a single 12-month, 365-day, year: