A cosmic calendar is a way to compare the age of the universe to the length of a single year, to help us understand how old the universe is. If one year was the same length as the age of the universe, the beginning of the universe would be the 1st of January. To compare the age of the universe to a single year, the cosmic calendar squishes all of time into one year. This means that the entire 14 billion year history of the universe happens in a single year, so each day would represent about 38 million years. By the end of December 31, all of time would be over.