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Telescopes are important tools used by scientists to see things that are far away. In astronomy, scientists use them to study things in outer space, like planets and stars. In image of a man with a telescope.

When were Telescopes Invented?

In 1608, Hans Lippershey invented the first telescope. Other scientists, like Galileo and Kepler, improved on his design. 
Since the invention of the first telescope, there have been many improvements made. Check out the Timeline of Early Telescopes and the Timeline of Modern Telescopes!
An image of an old brass telescope.

Telescopes have been around for hundreds of years!

Why are They Important?

If you go outside on a clear night and look up at the sky, you will see lots of shining stars. From Earth, these stars look like little specs of light.  
Because they are so far away, it’s hard for astronomers to learn about stars and planets. This technology allows scientists to see things in space as if they weren’t so far away. This makes it easier to study outer space. 
Telescopes can help scientists learn more about the planets in our solar system. Galileo used a telescope to discover the four largest moons of Jupiter and the phases of Venus. He also found sunspots on the surface of the Sun and observed features of the Moon!  

A sculpture of the bust of Galileo.

Galileo used an early telescope to discover new things about our Solar System.

Scientists can also use them to study things outside our Solar System. They use them to study other stars, solar systems, and even galaxies! Advanced versions can also help scientists search for extraterrestrial life. 

Two Main Types

There are two main types of telescope. They are the refracting telescope and the reflecting telescope.  

The Refracting Telescope

The refracting telescope was the first type invented. It uses a convex or concave lens to concentrate light to a focal point. This helps to magnify an image that is far away. 
Unfortunately, refracting telescopes have many flaws. They have something called “chromatic aberrations.” These aberrations create a rainbow of colors in the image, which can make it difficult to see. To try to fix this, scientists have to make refracting telescopes really long. 

The Reflecting Telescope 

Because of these problems, scientists began looking for a new way to make a telescope. In 1668, Isaac Newton created the first working reflecting telescope. 

A portrait illustration of Issac Newton.

Isaac Newton was a famous scientist who invented the reflecting telescope.

Unlike the refracting telescope, the reflecting telescope uses curved mirrors to reflect light. The light comes into the telescope and reflects off different mirrors. Then it leaves the telescope through an eyepiece. This telescope does not have chromatic aberrations. 

Other Types of Telescopes 

In recent years, there have been major improvements to telescopes. Scientists have created advanced telescopes that are much more powerful than traditional types. 
Advanced telescopes include the radio telescope, the X-ray telescope, and the gamma-ray telescope. These telescopes can detect wavelengths of light that the human eye cannot see. They are very important for making new discoveries about outer space. 
Watch this fun video to learn more about telescopes: