Cosmic Calendar


The Universe has existed for 13.8 billion years, but they’re just numbers we can’t really visualise. It’s hard to imagine what a kilometre is, to count a second correctly, so how can we fully understand what 13.8 billion years is? Possibly the best way that has been found so far is Carl Sagan’s Cosmic Calendar, condensing the 13.8 billion years into one calendar year that we can understand. Yet, it might be surprising to realize how much of the Universe has gone by without us, or really anything, around! This activity works to bring an understanding to how old and yet how young the Universe is. It also helps to put in perspective human and even Earth’s history on the grand cosmic scale. Students will be able to learn what has passed before us with major events like the Big Bang and even look into the future of our Solar System.

Background Information

The Universe came into existence 13.8 billion years ago with the Big Bang, but what happened between then and today? By picking major events like the first galaxies, the creation of our galaxy, the Solar System and first life, we can put into perspective the timescale of the Universe and where we are on it. We will scale the entire life of the Universe so far down to one calendar year. By putting the beginning of the Universe at 00:01 on January 1st and today at 23:59 on December 31st, we condense those 13.8 billion years into one year that we understand and can visualise more easily. We take these important events like the dinosaurs coming into existence and the domestication of fire, things that seem so important to us on Earth, and we compare when they happened to everything else and we see that in a blink of an eye we have done quite a lot. 

Then with the second year we look into the possible future of Earth and the Solar System. These are all hypothetical events, but it shows us that things which seem that they will last forever like the Pyramids of Giza will erode away in a short time on the scale of the lifetime of our Universe. This also opens up conversations about the Sun and its lifespan and life cycle, from a normal main sequence star to a red giant and then finally to a white dwarf, all in the lifetime of our Solar System. This will introduce students to the basics of solar physics by explaining how our Sun will evolve. 

Notable Events from the Big Bang to Today in a Spiral, with Each 90 Degrees Representing 1 Billion Years.
By Pablo Carlos Budassi – Own work, CC BY-SA 4.0,