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 intuition in 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”.
A graphical view of the Cosmic Calendar for presentations, featuring the months of the year, days of December, and the final minute.
Copied from https://en.wikipedia.org/wiki/Cosmic_Calendar