When Do The Clocks Change?
2022: Clocks go forward 27th March. Clocks go back 30th October
2023: Clocks go forward 26th March. Clocks go back 29th October
Greenwich Mean Time
Greenwich Mean Time or GMT is the time displayed by the Shepherd Gate Clock at the Royal Observatory in Greenwich, London. When the sun is at its highest point exactly above the Prime Meridian, it is 12:00 noon at Greenwich.
GMT is not affected by Daylight Saving Time (DST) clock changes.
The Greenwich Meridian (Prime Meridian or Longitude Zero degrees) is the reference point for every Time Zone in the world.
Every 15° longitude represents one hour's difference in time: (24 x 15 = 360, the degrees of a circle). You can work out the time at every location on earth if you know how many degrees it is east or west of Greenwich.
Quartz movements are very accurate and require minimal maintenance aside from battery replacements. They tend to be low-cost since they are battery powered and have few moving parts.
How a Quartz Movement Works
A quartz movement utilises a battery as its primary power source and is typically the type of movement that you will find in most clocks. To create power in quartz clock movements, a battery sends an electrical current through a small quartz crystal, electrifying the crystal to create vibrations. These vibrations keep the movement oscillating and drive the motor to move the clocks hands.
Some Interesting facts about clocks...
- With the invention of the pendulum clock in 1656, Christiaan Huygens increased the best accuracy of clocks from 15 minutes deviation a day to around 15 seconds a day
- An Institute in Colorado created a clock so accurate it won’t lose/gain a second in 20 million years. This is the clock used for internet time.
- Big Ben is the name of the largest of the five bells which hang within the clock and not the name of the landmark clock.
- Pennies are used to adjust the time in London’s Big Ben clock tower. A single penny can change the pendulum’s centre of mass and alter the time by 0.4s per day.
- “o’clock” is a contraction of “stroke of the clock” and comes from 15th century references to medieval mechanical clocks.
- Clockwise and counterclockwise were originally sunwise and widdershins before clocks were common.
- France once tried simplifying time by using a decimal clock, in which there were only 10 hours in a day.
- Before alarm clocks, there was a profession called a knocker-upper who would go around and knock on your door until you woke up.
- A massive clock, hundreds of feet tall, is currently being constructed inside a mountain in East Texas. It’s designed to withstand the test of time and expected to tick uninterrupted for over 10,000 years.
- Due to changes in local gravity, a pendulum clock accurate at sea level will lose around 16 seconds per day if moved to an altitude of 4000 feet.
- A simple test involving asking a patient to draw the face of a clock is used as a screening tool for Alzheimer’s and other types of dementia.
- A mechanical alarm clock was created by an American named Levi Hutchins in 1787. He made the device for himself and it only rang at 4 a.m., in order to wake him for his job. The French inventor Antoine Redier was the first to patent an adjustable mechanical alarm clock, in 1847, 60 years later.
- The clock’s hands moving ‘clockwise’ was intended to imitate the way the shadow on a sundial in the Northern hemisphere moves during the day