The Astronomical Influence of Galileo’s Telescope

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photo by Matthew Ansley, courtesy of Unsplash

Our naked, human eyes were not enough for to explore all the wonders that our universe has to offer. Fortunately, the invention of the telescope fixed this problem, magnifying objects and places literally worlds away.

The development of the original telescope took place between 1608 and 1609, based on the idea that a pair of lenses could be used to magnify an object. As telescopes evolved, they were classified into two distinct categories: refracting and reflecting telescopes. The difference was that the reflecting telescope used mirrors to focus light instead of lenses. However, both telescopes relied on gathering rays of light and converging them at a single focal point. Then, an image can be produced and it will appear larger and closer than it really is.

The Galilean telescope was a powerful refracting telescope invented by Galileo Galilei, a prominent Italian astronomer and physicist. The Galilean telescope has significantly impacted the world’s understanding of our universe through its remarkable ability to enlarge faraway objects.


The original invention of the telescope stemmed from both curiosity and practical desires. Once the invention of the telescope spread across Europe, it opened doors for people who wanted to challenge philosophical and religious ideas held common at the time. The telescope’s evolution was most obviously encouraged by astronomers who wanted to compare their own observations with the Ptolemaic theory, the idea that the Earth was the center of the universe, and that all other space objects revolved around it.

Additionally, in a more practical point of view, many people also believed that a telescope could be used in the military because of its capabilities to clear up blurry images or make it easier to see distant or indistinct objects.

Galileo, Lipperhey, and Aristotle

As the Galilean telescope took shape, Galileo’s work took into consideration the ideas of other important figures— not just his own expertise alone.

In fact, it was Hans Lipperhey of the Netherlands who made the Galilean telescope possible. Lipperhey owned a spectacle shop and he noticed that when he looked through two lenses, the steeple of a distant church seemed to look bigger. Lipperhey even allowed shop visitors to come in and test out the double-lens instruments.

When Galileo learned about Lipperhey’s device, he was intrigued and set out to replicate a similar object and enhance it which eventually led to Galileo’s famous telescope.

photo by K. Mitch Hodge, courtesy of Unsplash
sculpture of Galileo Galilei contemplating the nature of the universe

Equally significant was renowned philosopher Aristotle. European beliefs about the cosmos were heavily influenced by Aristotelian beliefs and Galileo was very motivated to improve or debunk these conceptions on his own. Later, Aristotle’s work would inspire Galileo to use scientific truths to verify and refute popular beliefs and ideas through the telescope, including the Ptolemaic theory and heliocentrism, the principle that the Sun is the center of our solar system.

Today’s telescopes

Even though refracting telescopes have very strong resolving power which allows them to make blurry images sharper and clearer, telescopes like that of Galileo’s were not perfect.

One major disadvantage to the refracting telescope is chromatic aberration which causes colored “fringes” to appear in the projected image. Fortunately, scientist and mathematician Isaac Newton solved this issue with the world’s first reflecting telescope. The reflecting telescope solved chromatic aberration by replacing the primary objective, the first lens, with a mirror that would reflect light instead of bending it.

These types of telescopes also inspired the radio telescope. The radio telescope is largely based on the same mechanism as the refracting telescope, but just applies the concepts to radio waves rather than visible light waves. Today, radio telescopes are used to manage and detect radio waves in outer space. This works by using a dish to gather the waves and convert them into electronic signals — a perfect parallel to the way that the Galilean telescope’s method of gathering rays of light.


Beyond sparking new innovations and new varieties of the telescope, Galileo’s telescope directly led to ground-breaking discoveries about our universe itself.

photo by Antoino Lopez, courtesy of Unsplash

The Galilean telescope could magnify objects up to 20 and 30 times. With this new power, the telescope revealed significant new information like the spots on the Sun, the rings of Saturn and the many moons of Jupiter. Being the strongest telescope of its time, Galileo’s telescope provided in depth scientific information about Earth and its relationship with other planetary objects.

To debunk the infamous Ptolemaic theory, Galileo’s telescope allowed for Galileo to witness an almost full Venus. In Ptolemaic theory, Venus could only show crescent and ‘new’ phases, never going through a complete cycle. This blatant contradiction showed that there existed multiple gravitational centers in the solar system and that Venus did not orbit the Earth. This discovery also allowed for the popularity of heliocentrism to rise and ultimately reshaped key ideas for dominant religions of the time period.

Closing remarks

The Galilean telescope has changed how astronomers and the general public look at our universe. The invention effectively rewrote the role of Earth in our solar system and shifted the core principles of dominant religions.

Today, the most famous telescope is the HST, or Hubble Space Telescope, which has become a global symbol for science. Practically, the Hubble Telescope uses photographic features to record detailed images about complex subjects like the life of a star, the formation of galaxies, and even the age of the universe.

In short, the telescope is still used today and will continue to play a major role in astronomy for years to come.

DeVorkin, David H., and Robert W. Smith. Hubble: Imaging Space and Time. National Geographic, 2013.

Hong, Sungook. “Optics and Light.” History of Modern Science and Mathematics, edited by Brian S. Baigrie, Charles Scribner’s Sons, 2002. Science In Context,

Richmond, Elliot. “Telescope.” Mathematics, edited by Mary Rose Bonk, 2nd ed., vol. 4, Macmillan Reference USA, 2016, pp. 95–101. Science in Context,

Smith, Robert W. “Astronomy and Space Science: The Telescope.” Scientific Thought: In Context, edited by K. Lee Lerner and Brenda Wilmoth Lerner, vol. 1, Gale, 2009, pp. 142–149. In Context Series. Science In Context,

“Telescope.” World of Physics, Gale, 2001. Science In Context,

“Telescopes.” Earth Sciences for Students, Macmillan Reference USA, 2008. Science In Context,

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