Cosmic Calendar

How can we humans, who rarely live more than a century, hope to grasp the vast expanse of time that is the history of the cosmos? In order to imagine all of cosmic time, we need to compress it into a single calendar year.

The Cosmic Calendar is a scale in which the 13.8-billion-year lifespan of our universe is mapped onto a single year. This chronological arrangement was done by famous astronomer Carl Sagan. In this mapping, the Big Bang took place on January 1st at 12 a.m., while the present moment is 12 p.m. on December 31st.

The Sun is older than the Earth, but it’s difficult to comprehend the massive age difference. Saying that the Earth’s age is 4.5 billion years, while the Sun’s age is 4.6 billion years, doesn’t actually seem to express how large that gap really is. It’s difficult for humans to wrap their heads around such time intervals thanks to our puny lifespan of barely 100 years.

For example, if someone were to ask an 8-year-old kid how much older his elder sister is, he’d probably give the answer correctly as 4 or maybe 5 years between them. However, that age difference looks huge to his 8-year-old self. However, it might not seem like a big deal to him when he’s fifty and there is no observable difference between his and his sister’s age.

Similarly, wouldn’t it be easier if we had the whole history of the Universe condensed down to a more relatable time scale so that we could actually appreciate the time differences between cosmological events?

In this visualization, the Big Bang took place on January 1st at 12 a.m., while the present moment is 12 p.m. on December 31st. Obviously, the condensation of 13.8 billion years into 365 days causes calendar time to speed up – a lot! At this rate, there are 438 years per second, 1.58 million years per hour 37.8 million years per day and about a billion years per month. In other words, an actual second is 13,812,768,000 times longer than a Cosmic Calendar second. However, this doesn’t mean that the Universe is going to end in this final second; the scale just continues condensing itself to accommodate the increasing age of the cosmos.

January 1st: 13.8 billion years ago, Big Bang

It’s as far back as we can see in time for now. Our entire universe emerged from a point trillions of times smaller than the period that ends this sentence. Space itself exploded in a cosmic fire, launching the expansion of the universe and giving birth to all the energy and all the matter we know today. Sounds crazy, but there’s strong observational evidence to support the Big Bang theory. And it includes the amount of helium in the cosmos and the glow of radio waves left over from the explosion. As it expanded, the universe cooled, and there was darkness for about 200 million years. Gravity was pulling together clumps of gas and heating them until the first stars burst into light on January 13th.

January 16th: 12.8 billion years ago, First Galaxies

After a billion years of pure energy moving across the cosmos, the first galaxies in the universe were formed. Gases began to come together and coalesce to form stars, which in turn began to cluster as a result of their own gravity. These galaxies merged to form still larger ones, including our own.

March 15th: 12.6 billion years ago, Milky Way

The Milky Way, our neighbourhood, was finally born after a million-year process of stars coming together to live in tandem after the first galaxies were formed. Hundreds of billions of suns. Which one is ours? It’s not yet born.

It will rise from the ashes of other stars. Stars die and are born in stellar nurseries called nebulas. They condense like raindrops from giant clouds of gas and dust. They get so hot that the nuclei of the atoms fuse together deep within them to make the oxygen we breathe, the carbon in our muscles, the calcium in our bones, the iron in our blood, all of it was cooked in the fiery hearts of long-vanished stars. You, I, and everyone is made of star-stuff. This star stuff is recycled and enriched, again and again, through succeeding generations of stars. How much longer until the birth of our Sun? A long time.

It won’t begin to shine for another six billion years.

August 31st: 4.57 billion years, Solar System

Our Solar System was formed when the Sun came into existence. Looking at this, it is surprising to observe that the Sun, born in September, is still incredibly young when compared to the age of the Milky Way.

September 6th: 4.54 billion years ago, Earth

The oldest rocks on Earth have been dated to be about 4.4 billion years old, which approximates Earth’s formation in the cosmic calendar just a week after the formation of the Solar System. As with the other worlds of our solar system, Earth was formed from a disk of gas and dust orbiting the newborn Sun. Repeated collisions produced a growing ball of debris. The Earth took one hell of a beating in its first billion years.

September 7th: 4.53 billion years ago, Moon

Just one day after Earth, our loyal satellite was formed and has been orbiting the Earth ever since. Fragments of orbiting debris during Earth’s formation collided and coalesced until they snowballed to form our Moon. The Moon is a souvenir of that violent epoch. If you stood on the surface of that long-ago Earth, the Moon would have looked a hundred times brighter. It was ten times closer back then, locked in a much more intimate gravitational embrace. As the Earth cooled, seas began to form. The tides were a thousand times higher then. Over the aeons, tidal friction within Earth pushed the Moon away.

September 28th: 3.8 billion years ago, Life on Earth

Most prominently, single-celled primitive bacteria signified the birth of life on the primordial Earth. We still don’t know how life got started. For all we know, it may have come from another part of the Milky Way. The origin of life is one of the greatest unsolved mysteries of science.

October 2n2: 3.2 billion years ago, Photosynthesis

This might be the most essential breakthrough for life since it signified the direct use of the Sun’s light to produce oxygen necessary for carbon-based life forms. All the earlier forms of life utilized only the Earth’s resources, but without photosynthesis, the atmosphere of Earth couldn’t be filled with oxygen.

December 5th: 850 million years ago, Multi-cellular Life

The evolutionary jump from primitive bacteria to multi-cellular organisms took a very long time but is responsible for life on Earth as we know it. This interval of almost 3 months is even longer than the time it took the first galaxies to form. Oh yeah, one other thing – these multicellular organisms invented sex.

December 17th: 540 million years ago, Cambrian Explosion

Life in the sea really took off, it was exploding with a diversity of larger plants and animals. The Earth began its journey to becoming lush and green when life took its first step onto land. Tiktaalik was one of the first animals to venture onto land. It must have felt like visiting another planet. The world was then being populated by amphibians and reptiles.

December 25th: 200 billion years ago, Dinosaurs

On the cosmic calendar, dinosaurs roamed the Earth for only 5 days.

December 30th: 65 billion years ago, Dinosaur Extinction

For more than a hundred million years, the dinosaurs were lords of the Earth, while our ancestors, small mammals, scurried fearfully underfoot. An asteroid impact changed all that – The non-avian dinosaurs died out, paving the way for mammals to conquer the world. Suppose the asteroid would have missed the Earth entirely: for all we know, the dinosaurs might still be here but we wouldn’t. This is a good example of the extreme contingency, the chance nature, of existence.

December 31st, 12 a.m.: 40 million years ago, Dawn of the Primates

Whatever we have heard about the history of mankind on Earth happened on December 31st of the cosmic calendar. This truly shows us the insignificance of our time spent here on Earth. The dinosaurs had roamed the Earth for 5 days, and we were still living in trees on the dawn of that final day. Humanity is quite literally a blip on this calendar, as everything that follows happened on the final day of the year. For more specificity, the time is been shown instead of the date:

  • 2:24 pm – Primitive humans were born.
  • 10:24 pm – Stone tools were used by humans and fire was domesticated.
  • 11:59 pm and 48 seconds – The Pyramids were built by the Egyptians.
  • 11:59 pm and 54 seconds – Buddha was born and the Roman Empire was formed.
  • 11:59 pm and 55 seconds – Christ was born, which marked the beginning of the Roman calendar (0 AD).
  • 11:59 pm and 58 seconds – Christopher Columbus discovered America.
  • 11:59 pm and 59 seconds – The world as we know it … with Batman in it.

1 thought on “Cosmic Calendar”

  1. Today, I went to the beachfront with my children. I found a sea shell
    and gave it to my 4-year-old daughter and said: “You can hear the ocean if you put this to your ear.” She put the shell to her ear and screamed. There was a hermit crab inside and it pinched her ear.

    She never wants to go back! LoL, I know this is completely off topic but I had to tell someone!

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