York Minster astronomical clock facts for kids
The York Minster astronomical clock was put into the North Transept of York Minster in 1955. It was first planned in 1944 and designed by R d'E Atkinson, who was a main assistant at the Royal Greenwich Observatory. This special clock is a way to remember the airmen from Yorkshire, Durham, and Northumberland who lost their lives during World War II.
Atkinson designed the clock to show how the sun and stars would look to a pilot flying over York. A C S Westcott and other skilled workers from the Royal Greenwich Observatory built the clock's parts and its two faces.
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What Does the Clock Show?
The front face of the clock shows where the sun and certain important stars would be if you were a pilot flying south over York Minster. It helps you see their positions in the sky.
The Main Plate
There's a round plate, about 62 centimeters across, that has a map of York Minster and the areas around it. This map includes city walls, rivers, and main roads. The edge of this plate shows the horizon, which is where the sky seems to meet the ground. The very center of the plate shows the point directly below the pilot.
The Star Map
Behind this plate is a star map called a planisphere. It's designed to show the stars as if you were looking down from the North Pole. This star map spins once every sidereal day, which is the time it takes for the Earth to complete one rotation relative to the stars.
The star map also has some basic star patterns, though they look a bit stretched out because of how the map is made. There's also a silver ring that shows the zodiac signs and the path the sun seems to follow through the year.
The Sun's Movement
A special sun symbol moves on the clock face. It shows the exact position of the sun. This symbol moves to show how the sun's path changes throughout the year. It also shows when the sun rises, reaches its highest point (called southing), and sets. The 'rays' from the sun symbol even show how long twilight lasts.
Sky Lines
To help pilots understand the sky, there are curved wires on the front face. These wires show lines of equal height in the sky. For example, some wires show where the sun would be at certain heights. Other wires form circles that meet at the center of the plate (the point directly below the pilot) and a point near the top (the point directly above the pilot).
How the Clock Works
The star map on the clock is connected to a large wheel. This wheel is moved by a special type of gear called a worm gear. This gear is linked to a gearbox with many other gears inside. These gears work together to make sure the clock keeps time very accurately, especially for showing the length of a year.
The clock uses an electric motor that runs at 1500 revolutions per minute. This motor helps power the gears and keep the clock moving precisely.
Time Dials
Below the main star map, there are three smaller dials. These dials show the hours, minutes, and seconds for Greenwich Mean Time. Next to them, three similar dials show the local sidereal time, which is a way of measuring time based on the stars. There's also a small window that shows the name of the day of the week.
The Back Face
The back face of the clock is also a star map. It's similar in size to the front one but is perfectly round. This map shows the brightest stars in important constellations that are always visible in the northern sky, like Ursa Major (the Big Dipper), Ursa Minor (the Little Dipper), and Cassiopeia. This back map also spins once a sidereal day, showing how these stars move around the North Celestial Pole.
Clock's History
The clock's working parts were damaged during a fire at York Minster on July 9, 1984. After ten years of repairs, the people who look after the Minster stopped winding the clock. This was because it wasn't keeping time as accurately as it should.
Images for kids
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The clock photographed in 2007.
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The grid system of the York Minster astronomical clock.
