The Cosmic Calendar is a method to visualize the

chronology of the universe The chronology of the universe describes the history and future of the universe according to Big Bang cosmology. Research published in 2015 estimates the earliest stages of the universe's existence as taking place 13.8 billion years ago, wit ...

, scaling its currently understood age of 13.8 billion years to a single

year A year or annus is the orbital period of a planetary body, for example, the Earth, moving in its orbit around the Sun. Due to the Earth's axial tilt, the course of a year sees the passing of the seasons, marked by change in weather, the ...

in order to help intuit it for pedagogical purposes in

science education Science education is the teaching and learning of science to school children, college students, or adults within the general public. The field of science education includes work in science content, science process (the scientific method), some ...

popular science ''Popular Science'' (also known as ''PopSci'') is an American digital magazine carrying popular science content, which refers to articles for the general reader on science and technology subjects. ''Popular Science'' has won over 58 awards, incl ...

. In this visualization, the

Big Bang The Big Bang event is a physical theory that describes how the universe expanded from an initial state of high density and temperature. Various cosmological models of the Big Bang explain the evolution of the observable universe from t ...

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 cosmic second, 1.575 million years per cosmic hour, and 37.8 million years per cosmic day. The concept was popularized by

Carl Sagan Carl Edward Sagan (; ; November 9, 1934December 20, 1996) was an American astronomer, planetary scientist, cosmologist, astrophysicist, astrobiologist, author, and science communicator. His best known scientific contribution is research on ...

in his 1977 book '' The Dragons of Eden'' and on his 1980 television series ''

Cosmos The cosmos (, ) is another name for the Universe. Using the word ''cosmos'' implies viewing the universe as a complex and orderly system or entity. The cosmos, and understandings of the reasons for its existence and significance, are studied in ...

''. 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 ishand".Episode 1: The Shores of the Cosmic Ocean (''Cosmos: A Personal Voyage'', Carl Sagan)
/ref> A similar analogy used to visualize the

geologic time scale The geologic time scale, or geological time scale, (GTS) is a representation of time based on the rock record of Earth. It is a system of chronological dating that uses chronostratigraphy (the process of relating strata to time) and geoch ...

and the history of life on Earth is the

Geologic Calendar The Geologic Calendar is a scale in which the geological lifetime of the Earth is mapped onto a calendrical year; that is to say, the ''day one'' of the Earth took place on a geologic January 1 at precisely midnight, and today's date and time is Dec ...

Cosmology

Date in year calculated from formula T(days) = 365 days * ( 1- T_Gya/13.797 )

Evolution of life on Earth

Human evolution

History begins

References

External links