Measuring Time

The measurement of time covers an incredible range. Here are some common time spans, from the shortest to the longest.

1 picosecond (one-trillionth of a second) - This is about the shortest period of time we can currently measure accurately.

1 nanosecond (one-billionth of a second) - 2 to 4 nanoseconds is the length of time that a typical home computer spends executing one software instruction.

1 microsecond (one-millionth of a second)

1 millisecond (one-thousandth of a second) - This is the typical fastest time for the exposure of film in a normal camera. A picture taken in 1/1,000th of a second will usually stop all human motion.

1 centisecond (one-hundredth of a second) - The length of time it takes for a stroke of lightning to strike

1 decisecond (one-tenth of a second) - A blink of an eye

1 second - An average person's heart beats once each second.

60 seconds - One minute; a long commercial

2 minutes - About as long as a person can hold his or her breath

5 minutes - About as long as anyone can stand waiting at a red light

60 minutes - An hour; about as long as a person can sit in a classroom without glazing over

8 hours - The typical workday in the United States, as well as the typical amount of sleep a person needs every night

24 hours - One day; the amount of time it takes for the planet Earth to rotate one time on its axis

7 days - One week

40 days - About the longest a person can survive without food

365.24 days - One year; the amount of time it takes for the planet Earth to complete one orbit around the sun

10 years - One decade

75 years - The typical life span for a human being

5,000 years - The span of recorded history

50,000 years - The length of time Homo sapiens has existed as a species

65 million years - The length of time dinosaurs have been extinct

200 million years - The length of time mammals have existed

3.5 to 4 billion years - The length of time that life has existed on Earth

4.5 billion years - The age of planet Earth

10 to 15 billion years - The suspected age of the universe since the big bang

SCIENTIFIC