The Cosmic Calendar
Squeeze the universe’s 13.8 billion years into one year, and humans arrive about 11 minutes before midnight on 31 December.
What’s going on
On this calendar, each second stands for about 440 years. The Big Bang is the first moment of 1 January. The Sun and Earth form in early September. The last of the giant dinosaurs vanish on 30 December. Modern humans appear about 11 minutes before midnight on 31 December, and all of written history fits into roughly the last 12 seconds. The astronomer Carl Sagan made this idea famous.
Myth
Humans have been around for most of Earth’s history.
Fact
On this calendar Earth exists for about four months before we arrive, in the final minutes.
Learn more
ESA, Planck results (age of the universe, 13.8 billion years); J.-J. Hublin et al., Nature 546, 289 (2017) (earliest Homo sapiens, about 300,000 years ago). Calendar times calculated by Xiqu Cards.
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