An Ancient Universe: How Astronomers Know the Vast Scale of Cosmic Time


The Cosmic Calendar

The Cosmic Calendar Activity. If we were to compress the history of the universe (from the Big Bang to the present moment) into one year, you can see where various "cosmic events" would fall in that year. The Earth and the other planets form around mid September. The first mammals don't emerge until December 26th, and the first humans come on the scene in the evening of December 31st. This kind of timeline activity helps students to see where human activities fit into the grand scale of cosmic time. The activity is available at

Return to An Ancient Universe
Appendix 2