Measuring time

Keeping track of time helps us make sense of our world. Read all about the history of timekeeping, find out who the pioneers of timekeeping were and learn about the instruments they created. Plus, discover what gems are on display at the Time & Longitude gallery of the Royal Observatory Greenwich.

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Because the Earth takes a little over 365 days to orbit the Sun, we need to make adjustments to keep the seasons from drifting: leap years and even leap seconds.

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