Giant lenses and mirrors 

Introduction

Telescopes use lenses or mirrors to collect light. Giant mirrors are easier to make than giant lenses, so all modern telescopes used by professional astronomers use mirrors.

Giant telescope mirrors are made up of lots of smaller mirrors that fit together. 

The biggest telescope mirror in space is on the James Webb Space Telescope. It is 6.5 metres high and made up of 18 gold-coated hexagonal mirrors. 

The biggest telescope mirror on the ground will be on the Extremely Large Telescope. It is 39 metres across and made of 798 hexagonal mirrors. 

Detailed Instructions for Visitors

This is simple wooden jigsaw with 9 different pieces. There is a tray on the right-hand side where the wooden pieces should be stored. The pieces are all different shapes and can be placed in the corresponding shaped slots in the large surface on the left-hand side. This rectangular surface represents the size of a professional football pitch. Then, each jigsaw piece has a tactile model on top of it. These are mostly telescope mirrors and lenses, which are all to the same scale as the football pitch and as each other. Therefore, by feeling their relative sizes you can get a sense of how big each mirror is.

On top of the rectangular piece there is a double decker bus. On top of the square piece is a car and a person. These should be useful references for understanding how big the telescope lenses and mirrors are compared to these everyday objects.

The quarter-circle shaped piece has a small circle on top of it. This circle represents the 63 centimetre wide lens inside the Newall telescope. This telescope was previously located in Gateshead. Now it is located under the sunnier skies of Greece.

The triangular shaped piece has a circle on top of it, which represent the 2.5 metre wide mirror inside the Isaac Newton Telescope. 2.5 metres is taller than even the tallest people, it is equivalent to 8 foot! You could compare the size of this mirror to the model of the person on the square shaped piece. This telescope was built by Grubb Parsons in Newcastle and despite being in the United Kingdom for a while, was moved to the sunnier skies of La Palma in the Canary Islands.

The star shaped piece has a circle on top of it, which represents the 2.4 metre wide mirror on the Hubble Space Telescope. This telescope orbits the Earth once every 95 minutes. It is moving very quickly!

The oval shaped piece has a circle on top of it, which represents the 3.9 metre wide mirror inside the Anglo-Australian telescope. This mirror was ground and polished in Newcastle, but the telescope is in Australia. A double decker bus is just over 4 meters tall, therefore this mirror is almost as high as a double decker bus! You can compare the size to the model of the bus on the rectangular shaped piece.

The trapezium shaped piece has an irregular shape on top of it. This shape represents the 6.5 metre tall mirror on the James Webb Space Telescope Mirror. The reason for the odd shape, is that this mirror is made from 18 smaller hexagonal shaped mirrors that are placed together. This meant that the mirror could be folded up when it was launched into space. There is a central hexagonal-shaped hole, where the lights goes inside to reach the cameras. It is now 1.5 million kilometres from Earth, with the mirror fully unfolded.

The octagonal shaped piece has a circle on top of it, which represents the 8.2 metre wide mirror inside the four telescopes called the Very Large Telescope, or VLT. Yes, they are really called the Very Large telescope! These telescopes are found in the Atacama Desert in Chile.

The final piece is shaped like a half circle. However, the model mirror on top is much larger than the jigsaw piece itself, so you might notice this first. This model mirror feels like a jagged-shaped circle. This is because the mirror is actually made from 798 smaller hexagonal pieces, that are all placed together to make one effective mirror that is 39 metres wide. This giant mirror will be found inside the Extremely Large Telescope, or ELT, which is currently being built in the Atacama Desert in Chile. Yes – the name is not very inventive, but this telescope will be the largest of its kinds for the foreseeable future. Go back to feel the size of the double decker bus. This mirror is the size of 9 double decker busses stacked on top of each other.