Who Invented the Telescope?

galileo and telescope
Galileo offering his telescope to three young women seated on a throne. He may not have invented the telescope, but he was the most famous user of his time. Painting by unknown artist. Library of Congress.

Next time you're out looking through a telescope at a distant star or planet, ask yourself: who came up with this idea in the first place? It seems like a simple idea: put lenses together to gather up light or magnify dim and distant objects. We've always had telescopes around, but we don't often stop to think about who came up with them. It turns out they date back to the late 16th or early 17th century, and the idea floated around for a while before Galileo picked up on it.

Did Galileo Invent the Telescope?

Although Galileo Galilei was one of the "early adopters" of telescope technology, and in fact, built his own, he was not the original genius who invented the idea. Of course, everybody assumes he did, but that's absolutely incorrect. There are many reasons why this mistake is made, some political and some historical. However, the real credit belongs to someone else.

Who? Astronomy historians aren't sure. It turns out they can't really credit the inventor of the telescope because no one knows for sure who it was. Whoever did it was the first person to put lenses together in a tube to gaze at distant objects. That started a revolution in astronomy. 

Just because there's not a good and clear chain of evidence pointing to the actual inventor doesn't keep people from speculating about who it was. There are some people who are credited with it, but there's not proof that any one of them was "the first." However, there are some clues about the person's identity, so let's take a look at the candidates in this optical mystery.

Was It the English Inventor?

Many people think that Leonard Digges invented both the reflecting and refracting telescopes. He was a well-known mathematician and surveyor as well as a great popularizer of science. His son, the famous English astronomer, Thomas Digges, posthumously published one of his father's manuscripts, Pantometria and wrote of the telescopes used by his father.

However, political problems may have prevented Leonard from capitalizing on his invention and getting the credit for having thought of it in the first place. 

Or, Was It the Dutch Optician?

In 1608, Dutch eyeglass maker, Hans Lippershey offered a new device to the government for military use. It used two glass lenses in a tube to magnify distant objects. he certainly seems to be a leading candidate for inventor of the telescope. However, Lippershey might not have been the first to think of the idea. At least two other Dutch opticians were also working on the same concept at the time. Still, Lippershey has been credited with the telescope's invention because he, at least, applied for the patent for it first. 

Why Do People Think Galileo Galilei Invented the Telescope?

We're not sure who was the first to invent the telescope. But, we definitely know who used it soon after it was developed: Galileo Galilei. People likely think he invented it because Galileo was the most famous ​user of the newfangled instrument. As soon as he heard about the wondrous device coming out of the Netherlands, Galileo was fascinated. He began constructing his own telescopes before ever seeing one in person. By 1609, he was ready for the next step: pointing one at the sky.

That's the year he began using telescopes to observe the heavens, becoming the first astronomer to do so.

What he found made him a household name. But, it also got him in a lot of hot water with the church. For one thing, he found the moons of Jupiter. From that discovery, he deduced the planets might move around the Sun the same way those moons did around the giant planet. He also looked at Saturn and discovered its rings. His observations were welcome, but his conclusions were not. They seemed to completely contradict the rigid position held by the Church that Earth (and humans) were the center of the universe. If these other worlds were worlds in their own right, with their own moons, then their existence and motions called the Church's teachings into question. That couldn't be allowed, so the Church punished him for his thoughts and writings.

That didn't stop Galileo. He continued to observe most of his life, constructing ever-better telescopes with which to see the stars and planets. 

So, while Galileo Galilei most certainly did not invent the telescope, he made great improvements in the technology. His first construction magnified the view by a power of three. He quickly improved the design and ultimately achieved a 20-power magnification. With this new tool, he found mountains and craters on the moon, discovered that the Milky Way was composed of stars, and discovered the four largest moons of Jupiter.

Revised and updated by Carolyn Collins Petersen.