Frequently Asked Questions - FAQs

Greenwich has spent a third of a millennium cracking the conundrum of time. Actually since ince King Charles II appointed John Flamsteed as the first Astronomer Royal in 1675. The opening of the New World and the search for accurate time-keeping to aid navigation gave the world GMT and the Prime Meridian .

• When did this millennium (century) begin and why ?

• What is Greenwich Mean Time (GMT)?

• What is midday and midnight?

• What is Co-ordinated Universal Time (UTC)?

• When will British Summer Time (BST) be in force?

• When was British Summer Time (BST) introduced?

• What is the definition of a second?

• What is the International Atomic Time Scale?

• What is the SI unit of time?

• What is the ISO standard format of time

• Why do clocks use roman IIII rather than IV?

• Why is the Navy so involved in time-keeping?

• What time does the time-ball drop?