The Cosmic Calendar


What is the Cosmic Calendar?

Carl Sagan, a famous astronomer, promoted this idea of the cosmic calendar, that essentially is a tool used to help people visualize and understand how far apart events in the Universe are. Sagan has chronologically arranged the hallmark events of the Universe’s 13.8 billion year lifespan into just a single year. In this demonstration, the Big Bang took place on January 1st at midnight, while the present moment is noon on December 31st. To condense all of time into 365 days, the rate of time has to accelerate quite a bit. To be exact, there are 438 years per second, 1.58 million years per hour, and 37.8 million years per day.

Important Events

Daily Express

On January 1, 13.8 billion years ago, the Universe was created as a result of what we call the Big Bang.

January 22, 12.85 billion years ago, the first galaxies in the universe were formed. Essentially, a mixture of different gases collided together to form stars, which in turn began to group together as a result of their own attraction to each other.

On March 16, 11 billion years ago, the Milky Way galaxy was born after the continued process of stars coalescing and living together.

Huffington Post UK

August 28, 4.57 billion years ago, the Solar System was formed when the Sun was born.

On September 6, 4.54 billion years ago, Earth came into existence.

September 7, 4.53 billion years ago, the Moon began its orbit around Earth.

On September 30, 3.8 billion years ago, single-celled primitive bacteria was the first sight of life on Earth.

December 5, 0.8 billion years ago marks the first multicellular organisms on Earth.


On December 25, 0.23 billion years ago, dinosaurs were roaming the Earth.

December 30, 0.065 billion years ago, a meteorite hit Earth and killed almost every every life form allowing mammals to now take over.

The Canadian

December 31, 40 million years ago begins the history of mankind on Earth. This shows how insignificant we are in regards to the history of the universe. Everything that has happened with humans has occurred on the final day of the year.

  • At 14:24 hours: primitive humans were born.
  • At 22:24: stone tools and fire were domesticated and used by humans to survive.
  • At 23:59 hours and 28 seconds: the Pyramids were built by the Egyptians.
  • At 23:59 hours and 54 seconds: Buddha was born and the Roman Empire was formed.
  • At 23:59 hours and 55 seconds: Christ was born, marking the beginning of the Roman calendar.
  • At 23:59 hours and 58 seconds: Christopher Columbus sailed across the ocean and discovered America.
  • At 23:59 hours and 59 seconds: the world as we know it today.

5 thoughts on “The Cosmic Calendar

  1. What an interesting article! I particularly appreciated your explanation of ideas originating from Carl Sagan and think that it’s fascinating to think about the scale of the universe both in regard to time and size. Did writing this post change your perspectives at all?


    1. Yes! When I think about human evolution I think about all the time that had to passed to get where we are today. However, when you look at the grand scheme of things those years are so insignificant. in relation to the development of the Universe.


  2. It’s so incredible to think not only about how long intelligent life has existed, but also how long it took for primitive unicellular life to evolve into the complex organisms that roam the earth today compared to the approximate age of the universe. I think being able to boil the timeline of the universe down to a timescale familiar to us really emphasizes how long life has existed on Earth and especially the time it took for unicellular organisms to develop into multicellular organisms. If this wasn’t amazing enough, imagine how infinitesimally small the amount of time life existed on the Earth would compare to the age of the universe at its demise!


  3. I know you know this, but astronomy is so less precise than other sciences predicting dates and distances. We try to wrap our brains around it using a calendar when really all these are approximations for times of events. It’s the best we can do!


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