• Life of a bright star
• Death of a bright star
• Age of the Universe
• Time for the Earth to go once around the Sun
• Time for Jupiter to go once around the Sun
• Time for light to travel from another galaxy to us
• Time for light to travel from a distant quasar to us
• Time since the great dinosaur extinction event
• Time for the Sun to go once around the Galaxy
• Life of a human being
• Age of human beings (first Homo sapiens)
• Time for light to travel from the Sun to the Earth
• Time for light to travel from the Sun to the nearest star

• one-hundred million years

A terrestrial planet (like Earth) being bombarded by comets. [NASA/JPL-Caltech]