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The Cosmic Calendar

Welcome to a short walk through creation, a stroll across the 15 billion years of our universe. Every step you take will be equivalent to approximately 30 million years and the whole of time, as we know it, will be compressed into an easy amble to the village shop!

Head for the pedestrian gate out of the playground.
Chapter one

15,000,000,000 Years Ago


We call this moment the Big Bang, when our universe forms and the first energies of creation begin to evolve. This rapid expansion and cooling, allows matter to form and spin through an ever growing sphere of space. At this point only fundamental particles exist - the elements of the periodic table: oxygen, carbon, chlorine, lead, iron, beryllium, gold and so on, will have to wait.

Walk on, and hundreds of millions of years will pass beneath your feet...
Go up the road towards the village. Take the first left, Carters Lane, and follow it for the pedestrian route to the village.
Chapter two

13,000,000,000 Years Ago

Two billion years have passed. Those first fundamental particles have merged to form primordial elements such as hydrogen and helium in huge gas clouds.

These clouds have collapsed under gravity to form the first stars, hot enough to fuse new elements such as oxygen and nitrogen within their nuclear cores.

Billions of these stars are grouped to form galaxies and thousands of galaxies mass within galactic clusters and superclusters. Eventually there will be more stars in the universe than grains of sand on all of Earth's beaches, each an elementary factory, releasing huge amounts of energy through the fusion reactions that create all the elements of the periodic table. Every piece of matter on Earth, in every tree, in every beast, in your shoes, your food, your skin, your brain, your breath, will be formed within a far off star and blown across the depths of space in that star's explosive death.

13,000,000,000 ago our galaxy, the Milky Way, takes shape. Somewhere within its hundreds of billions of stars the particles that make you are being forged...
Keep on for the village. Head for the Butter Cross.
Chapter three

5,000,000,000 Years Ago

Ten billion years have passed since the Big Bang, two thirds of the life of our universe.

In an outer spiral arm of the Milky Way, gravity has caused the center of a rotating cloud of gas to collapse in upon itself and there is enough pressure at its heart to kick-start nuclear fusion. Our sun, Sol, explodes into light, fusing hydrogen into helium and releasing immense waves of energy at the same time. Much of the gas cloud surrounding the new star is blown away into space, but the heavier elements remain in orbit and slowly form into planets under the influence of their own gravity.

The third planet from the sun is a molten mass of elements that were formed within the hearts of long dead stars. As the planet slowly cools, it forms an iron core while the mostly lighter elements rise toward a gradually solidifying crust. Volcanoes vent gases and water vapour, which condense, eventually leading to the creation of steaming oceans.

One day this planet will harbour life, some of whom will name it "Earth".
Head for the pub!
Chapter four

4,000,000,000 Years Ago

Eleven billion years have passed. If the lifetime of the universe was compared to a year, with The Big Bang taking place on the first of January, then the earliest life of Earth emerges sometime in mid September. In the hot primordial soup of the young Earth's oceans, probably on rocks beside underwater volcanic vents, the first micro-organisms begins to evolve (micro-fossils as old as 4.28 billion years old have been discovered in hydrothermal vent precipitates in the Nuvvuagittuq Belt of Quebec, Canada).

Some of these first micro-organisms are cyanobacteria, a bacteria that harnesses algae within its cells to give it energy through photosynthesis. Photosynthesis also produces oxygen and it could be that we have cyanobacteria to thank for the oxygen that today makes up 20% of our atmosphere!

Cyanobacteria still thrives today; it causes the blue-green algal blooms that sometimes cover our rivers, lakes and bays in summer. If you come across it you are looking at one of the earliest and most successful forms of life!
Chapter five

...a footnote

If you want to travel back in time to wander amongst the very first lifeforms, and you don't fancy boiling yourself alive beside a deep ocean hydrothermal vent, then visit the stromatolites of Western Australia. These astounding black mounds, found in shallow hyper-salty sea water each contain a layer of cyanobacteria that adds around half a millimeter of material to the mound each year. Some are 50m tall, making them approximately 3 billion years old!
The village shop is the end of our trail. Be prepared because the whole history of life on Earth will have to fit in before you get there!
Chapter six

500,000,000 Years Ago

Over fourteen billion years have passed out of the fifteen billion years the universe has existed, and the first fish have evolved.

There is enough oxygen in the atmosphere to support larger forms of life and a plethora of species are evolving in the oceans, feeding upon the plentiful algae, and each other!
Chapter seven

...many mass extinctions!

In 400 million years time (around ten paces) a huge meteorite will smash into the Earth, creating a crater that we know today as the Gulf of Mexico and ejecting a massive amount of dust into the already suffocating atmosphere. This will be enough to kill off the last of the dinosaurs, along with 50% of the species on Earth, paving the way for the rise of the mammals.

You've probably heard of this, the last mass extinction, but what do you know of the ones that came before it?

Before you take another step the first great, but brief, ice age will wipe out 86% of Earth's species such as these graptolites, ancient ocean living filter feeders.

Now, walk on...
Walk on...
Chapter eight

450,000,000 Years Ago

With every pace you cross 30 million years. Now life has left the oceans and plants begin to colonise the land, enabling just 50 million years later the evolution of crawling and flying insects. Flowers won't evolve for another ten paces (or 300 million years) so for now insects feed on plants and other animals for nutrients.
Fish evolve into amphibians that in turn evolve into reptiles - scales to skin and back to scales again!

The new land plants are believed to be the most likely culprits for the Devonian Mass Extinction, in which 75% of all species on Earth died out! It's believed that the plants' roots drew nutrients up out of deep soil from where they were washed into the oceans, causing huge algal blooms that used up much of the oxygen in the atmosphere, suffocating life.
Keep going. Every step you take is covering 30 million years!
Chapter nine

250,000,000 Years Ago

251,000,000 million years ago (about half a centimeter behind you!) is 'The Great Dying', a mass extinction that wipes out 96% of the species on Earth! A combination of supermassive volcanic activity belching out carbon dioxide and marine algae responding with methane results in global warming and acidification of the oceans that nearly wipes out all life on Earth.

But life survives and eventually thrives again, and from the remaining reptiles rise the dinosaurs! For two hundred million years these 'Terrible Lizards' will rule, eventually succumbing to the tides of time. They are still with us today in a somewhat smaller, less terrifying form; that of birds! Wonderfully well preserved fossils, along with modern imaging methods, have proved that most, if not all, dinosaurs had feathered body parts, just like their descendants today!

Around 140 million years ago, midway through the age of the dinosaurs, the first mammals evolve from small reptiles. These early, shrew-like creatures lay eggs, much like the echidna and platypus today.

These early mammals will survive the mass extinction that wiped out the dinosaurs. Their time will soon come...
1cm on the ground is 3 million years of time passing. As you approach the village shop, all of mammalian history lies in your last three steps...
Chapter ten

55,000,000 Years Ago

All of human history lies between here are the village shop. In fact, every human being you have ever heard of and every event in human history can be found within half a centimeter of the village shop's door!

Between where you stand now and the village shop lies the evolution of all the animals since the age of the dinosaurs. Crocodiles, sharks, nautilus, jellyfish, sponges, monkey puzzle trees, mosses and many more organisms have survive the dinosaurs, and are now joined by such species as zebras, koalas, wolves, dolphins, ostriches, kestrels, dandelions!

One of the new groups of mammals to evolve is the primates. These creatures originally live in trees, and many species still do (the ancestors of gorillas, lemurs, orangutans and chimpanzees), but some will leave the forests and make the grasslands of what is now Africa their home. These are early ancestors of humans and the fossil record shows a gradual evolution of species from these early primates to modern humans.

Move to one centimeter away from the village shop door. The doorway is the present day and the school is at the birth of the universe. In the distance between you and the door lies the evolution of Homo Habilis, arguably the first 'human' and the first to use stone tools, Homo Erectus and Homo Neanderthalis, all of whom are now extinct.

A millimeter from the doorway will evolve Homo Sapiens, the modern human. You.

Within that millimeter lies the stone age; the Ancient Egyptians; great Chinese empires; Alexander the Great; Jesus, Buddha and Confucius; viking longships; the Tudors; William Shakespeare; every war you've ever heard of; every invention every made; every marriage; every party; every one of your relatives and mine!

We are a tiny part of the history of a very large universe, but this hair's breath of existence is everything that we have. All paths have led to this point, paused in a doorway...

... what is important to us, and where do we go next?
As you leave the village shop do please walk a little way back down the road and consider what you have read... more may be revealed!
Chapter eleven

Thanks go to Carl Sagan, whose 'Cosmic Calendar' inspired this walk across creation. Before googling 'Carl Sagan Cosmic Calendar' do please read some of his words:"The size and age of the Cosmos are beyond ordinary human understanding. Lost somewhere between immensity and eternity is our tiny planetary home. In a cosmic perspective, most human concerns seem insignificant, even petty. And yet our species is young and curious and brave and shows much promise. In the last few millennia we have made the most astonishing and unexpected discoveries about the Cosmos and our place within it, explorations that are exhilarating to consider. They remind us that humans have evolved to wonder, that understanding is a joy, that knowledge is prerequisite to survival. I believe our future depends powerfully on how well we understand this Cosmos in which we float like a mote of dust in the morning sky."
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