A telescope is a tool that helps astronomers see things that are far away

A lens is a clear piece of curved glass that bends light to help us see things clearly

A telescope that uses lenses is called a refracting telescope

What is a Telescope? 

In the past, telescopes used curved pieces of see-through material called lenses to gather light. Nowadays, most telescopes use curved mirrors instead to collect light from the night sky. The shape of the mirror or lens in a telescope helps concentrate the light, and that’s what we see when we look through a telescope.

A telescope is a tool that helps astronomers see things that are far away. Most telescopes, especially the big ones, use curved mirrors to collect and concentrate light from the night sky.

In the past, the first telescopes used curved pieces of clear glass called lenses to gather light. But nowadays, we use mirrors instead. Mirrors are lighter and easier to make really smooth compared to lenses, which is why we use them in telescopes today.

A lens is a clear piece of curved glass that bends light to help us see things clearly. A mirror is a shiny surface that reflects light. In telescopes, mirrors are used to gather and focus light from the sky because they are lighter and easier to make smooth.

The parts of a telescope that are called “optics” are either mirrors or lenses. Powerful telescopes can see things that are very dim and far away. To do that, the optics, whether they are mirrors or lenses, need to be really big.

When the mirrors or lenses in a telescope are larger, they can collect more light. The shape of the optics helps to concentrate the light. This concentrated light is what we see when we look through the telescope.

The optics in a telescope need to be nearly perfect. This means the mirrors and lenses must have the right shape to concentrate the light, without any spots, scratches, or flaws. If there are problems, the image becomes distorted or blurry and is hard to see. Making a perfect mirror is difficult, but making a perfect lens is even harder.

Lenses 

A telescope that uses lenses is called a refracting telescope.

A lens, like the one in eyeglasses, bends light when it goes through it. This helps to make things clearer for our eyes. In a telescope, the lens also bends light and makes faraway objects appear closer to us, so we can see them better.

When people have really poor eyesight, they sometimes need glasses with big, thick lenses. These lenses are strong and help them see better. Telescopes also use big lenses to see faraway things. But big lenses can be heavy and hard to use. They work by bending and focusing light to make things look bigger and clearer. They help us see more details and can also help with vision problems.

For the light to pass through the lens properly, the surface of the lens needs to be really smooth. If there are any problems or imperfections on the lens, it will affect the image you see. It’s like trying to look through a dirty window, and things won’t appear clear.

Why do mirrors work better? 

A reflecting telescope refers to a telescope that employs mirrors instead of lenses.

A mirror used in a telescope can be really thin, unlike a lens. Even if it’s big, it doesn’t have to be thick. Instead of bending the light is concentrated by bouncing  off  the mirror.To do this, the mirror needs to have a right curved shape.

Making a large, almost perfect mirror is much simpler compared to making a large, almost perfect lens. Additionally, mirrors are easier to clean and polish because they only have one side.

The best thing about mirrors is that they are not heavy. Because they are much lighter than lenses, it’s a lot easier to send them into space.

Telescopes in space, like the Hubble Space Telescope and the Spitzer Space Telescope, have helped us see far-off galaxies and colorful clouds called nebulas outside our solar system.

The James Webb Space Telescope is the biggest and strongest space telescope ever made. It will help scientists see what the universe was like around 200 million years after the Big Bang.

(The author Girish Linganna is a Defence, Aerospace & Political Analyst based in Bengaluru. He is also Director of ADD Engineering Components, India, Pvt. Ltd, a subsidiary of ADD Engineering GmbH, Germany. You can reach out to him at: [email protected])