Time | Royal Museums Greenwich

Greenwich Mean Time

What is Greenwich Mean Time (GMT) - and why does it matter?

How did local clock time in Greenwich change the world?

Time and navigation

When do the clocks go forward?

Marking the start of British Summer Time, the clocks 'spring forward' in March, meaning we'll lose an hour's sleep

Time and navigation

What is the Prime Meridian and why is it in Greenwich?

How Greenwich found its place in the centre of global time and navigation

Two watches with starry sky faces, one with a blue strap and one brown

15% off timepieces: limited offer

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Greenwich Mean Time

Discover why Greenwich is known as 'the home of time'

History of the Royal Observatory

Find out more about the founding of the Royal Observatory, and how Greenwich came to be known as the 'Home of Time'

Time before Greenwich Mean Time: the confusing case of the traveller's watch

Before time became standardised, different areas of the country all kept their own 'local time'. This gold traveller's watch with two minute hands shows how tricky that could be

The Greenwich Time Lady: Ruth Belville

Discover the story behind the media sensation Ruth Belville, who brought the correct time from the Royal Observatory to London for almost 50 years.

What is Greenwich Mean Time (GMT) - and why does it matter?

How did local clock time in Greenwich change the world?

The Greenwich Time Ball and one time for all

How do you know that your watch, clock or phone is telling exactly the right time? At one time, the only way was to look to the roof of the Observatory.

British Summer Time (BST) and Daylight Saving - understanding UK time changes

Why does UK time change, and when was British Summer Time first introduced? Explore the history of BST and daylight saving

Clocks and timekeeping

Read all about the history of timekeeping and the amazing instruments in Royal Observatory Greenwich's collection

A history of the Royal Observatory in six objects

Explore 350 years of the world-renowned institution and the people who worked there through six intriguing objects

When do the clocks go back?

Marking the end of British Summer Time, the clocks go back in October, giving us an extra hour in bed

The lost chronometer: the timepiece that sailed with Charles Darwin and Sir John Franklin

Learn more about the marine chronometer that journeyed on board HMS Beagle before being lost at sea during Sir John Franklin's disastrous expedition

Time before Greenwich Mean Time: the confusing case of the traveller's watch

Before time became standardised, different areas of the country all kept their own 'local time'. This gold traveller's watch with two minute hands shows how tricky that could be

The BBC pips: the Royal Observatory and the Greenwich Time Service

Discover the story behind the Greenwich time pips, first broadcast by the BBC over 100 years ago in 1924

What is a nocturnal?

Learn more about the nocturnal or ‘nocturlabe’, used for centuries to tell the time based on the movement of the stars

The Greenwich Time Lady: Ruth Belville

Discover the story behind the media sensation Ruth Belville, who brought the correct time from the Royal Observatory to London for almost 50 years.

When do the clocks go forward?

Marking the start of British Summer Time, the clocks 'spring forward' in March, meaning we'll lose an hour's sleep

Which years are leap years and can you have leap seconds?

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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Royal Observatory Greenwich is Britain’s oldest purpose-built scientific institution. Founded in 1675, it is the birthplace of modern astronomy and the home of Greenwich Mean Time.

Seasons and calendars

Keeping track of time helps us make sense of our world. Explore how people around the world divide time and mark the changing years

What and when is the autumnal equinox?

When is the autumnal equinox, what date does the autumnal equinox fall on and when does summer end?

Lunar new year dates and animals of the zodiac

Find out more about the new year festival celebrated by people across Asia

Summer and winter solstices explained – how the Sun determines the longest and shortest days of the year

Find out how the position of the Sun determines the longest and shortest days of the year in this special Royal Observatory Greenwich Illuminates extract

When does spring start?

Blooming daffodils, warmer weather or the Sun's position in the sky – how do we define the beginning of spring?

How to make a Hong Bao for Lunar New Year

Create your own hong bao, using origami techniques, to celebrate the Lunar New Year.

How to make a lucky fish poster for Lunar New Year

Create a lucky fish poster to decorate your home for Lunar New Year.

How do people celebrate Chinese New Year?

What happens during Chinese New Year? The Newham Chinese Association explain some of the traditions, festivals and customs that take place when Chinese New Year is celebrated

Summer solstice

When - and what - is the summer solstice? Understand the science behind the solstice with Royal Observatory Greenwich

When is the winter solstice? The shortest day

When is the winter solstice this year? What does it mean? Is it the shortest or longest day?

Time and navigation

How are measuring time and measuring distance linked? Why is the Prime Meridian in Greenwich? Learn more about the links between time, navigation and astronomy

Zooming in on conservation: the treatment of a 17th century telescope

This beautiful 17th-century telescope needed careful treatment before going on display. Object Conservator Rachel Roberts eyed up the issues

The lost chronometer: the timepiece that sailed with Charles Darwin and Sir John Franklin

Learn more about the marine chronometer that journeyed on board HMS Beagle before being lost at sea during Sir John Franklin's disastrous expedition

Early charts from the Mediterranean

The Caird Library and Archive’s display case highlighted three colourful charts from the rich cartographic collection of Royal Museums Greenwich.

True north and magnetic north: what's the difference?

In September 2019, for the first time in over 360 years, compasses at Greenwich pointed true north. But what does this mean - and haven't compasses always pointed 'north'?

What is longitude?

Find out what longitude is and what makes it so hard to measure

What made the search for longitude so important?

Why did most of the great European powers offer huge rewards for a way to determine longitude at sea?

Longitude found: Nevil Maskelyne and the lunar method

Find out how the celebrated Astronomer Royal helped to solve the longitude problem

Longitude found - the story of Harrison's timekeepers

Who was John Harrison, and how did his clocks help to solve the problem of finding longitude at sea?

What is the Prime Meridian and why is it in Greenwich?

How Greenwich found its place in the centre of global time and navigation

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Royal Museums Greenwich is a charity, and we rely on your support to care for our collections and help everyone appreciate the history of time and the Royal Observatory. Donate today and help shape the Museum's future

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What is Greenwich Mean Time (GMT) - and why does it matter?

When do the clocks go forward?

What is the Prime Meridian and why is it in Greenwich?

15% off timepieces: limited offer

History of the Royal Observatory

Time before Greenwich Mean Time: the confusing case of the traveller's watch

The Greenwich Time Lady: Ruth Belville

What is Greenwich Mean Time (GMT) - and why does it matter?

The Greenwich Time Ball and one time for all

British Summer Time (BST) and Daylight Saving - understanding UK time changes

A history of the Royal Observatory in six objects

When do the clocks go back?

The lost chronometer: the timepiece that sailed with Charles Darwin and Sir John Franklin

Time before Greenwich Mean Time: the confusing case of the traveller's watch

The BBC pips: the Royal Observatory and the Greenwich Time Service

What is a nocturnal?

The Greenwich Time Lady: Ruth Belville

When do the clocks go forward?

Which years are leap years and can you have leap seconds?

Time to subscribe?

Watch

This content is hosted by a third party

What and when is the autumnal equinox?

Lunar new year dates and animals of the zodiac

Summer and winter solstices explained – how the Sun determines the longest and shortest days of the year

When does spring start?

How to make a Hong Bao for Lunar New Year

How to make a lucky fish poster for Lunar New Year

How do people celebrate Chinese New Year?

Summer solstice

When is the winter solstice? The shortest day

Zooming in on conservation: the treatment of a 17th century telescope

The lost chronometer: the timepiece that sailed with Charles Darwin and Sir John Franklin

Early charts from the Mediterranean

True north and magnetic north: what's the difference?

What is longitude?

What made the search for longitude so important?

Longitude found: Nevil Maskelyne and the lunar method

Longitude found - the story of Harrison's timekeepers

What is the Prime Meridian and why is it in Greenwich?

Discover more from the 'Home of Time'

A timeless gift