Time

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We use time to measure the past, the present and the future.

To measure time, we can use anything that repeats itself regularly. An example is the number of times the Earth rotates (spins around). This is measured in "days". The number of orbits it makes around the Sun is measured in "years". The study of time measurement is horology.

The SI (Systeme Internationale) unit of time is one second, written as s.

[edit] Units of time

  • 1 millennium = 1000 years
  • 1 century = 100 years
  • 1 decade = 10 years
  • 1 year = 12 months = 365 days (every 4 years 366 days)
  • 1 month ≈ 4 weeks ≈ 30 days
  • 1 fortnight = 2 weeks
  • 1 week = 7 days
  • 1 day = 24 hours
  • 1 hour = 60 minutes
  • 1 minute = 60 seconds
  • 1 second = 100 centiseconds
  • 1 second = 1000 milliseconds
  • 1 decisecond = 10 centiseconds
  • 1 centisecond = 10 milliseconds
  • 1 millisecond = 1000 microseconds
  • 1 microsecond = 1000 nanoseconds
  • 1 nanosecond = 1000 picoseconds
  • 1 picosecond = 1/1,000,000,000,000 of a second
  • 1 femtosecond = 1/1,000,000,000,000,000 of a second

[edit] Things to measure time

[edit] Time of day