The Telescope: See space for yourself

The telescope is an instrument used for the observation of remote objects through a cylinder that captures visible light (or other electromagnetic radiation) and convex or concave lenses. The lens closest to the object is known as the objective lens, while the lens closer to the user’s eye is known as the eyepiece lens. Here’s a 6-minute rundown by Mr. Wizard on how telescopes work:

Source: MrWizardStudios

Greek astronomer, cartographer and mathematician Ptolemy is known as the first person to write about the properties of light, which included reflection, refraction and colour. Ibn Sahl (a Persian-Muslim mathematician, physicist and optics engineer) created the law of refraction.

The history of the modern telescope has traveled through the writings of many scholars. Thomas Digges (an English mathematician and astronomer) wrote that his father, Leonard Digges, created something akin to the telescope in 1570. Ottoman astronomer and engineer Taq ad-Din also alluded to creating a device after reading a Greek book in 1574.

The first concrete design of the telescope came from Hans Lippershey, a Dutch lensmaker, in 1608. His invention had 3x magnification and used an objective lens and eyepiece lens to bend and focus light. It has been long debated if Lippershey was actually the first person to build a telescope (for the purpose of observing extra-terrestrial objects), but he definitely got the patent for it first and made money when others reproduced his instrument.

In 1609, Galileo improved upon Lippershey’s design and named it a “perspicillum”. Greek mathematician Giovanni Demisiani coined the word “telescope” after seeing one of Galileo’s instruments.

Galileo’s perspicillum diagram. Source: Universe Today
Galileo’s original perspicillum, preserved at the Museo Galileo in Italy. Source: Universe Today

In 1611, Johannes Kepler wrote of a telescope that used a convex lens for the eyepiece (rather than Galileo’s concave lens), which went on to be known as the Keplerian telescope. It was constructed in 1630 by Christoph Scheiner.

Diagram of a perspicillum (note the concave lens). Source: Joan L Richards
Diagram of a Keplerian telescope (note the convex lens). Source: Joan L Richards

After the creation of Galileo’s perspicillum and Kepler’s telescope, many telescopes of different specifications, lenses and magnifications were created throughout the 20th century. A shorter and more functional refracting telescope was created in 1733 by Chester Moore Hall, which used an achromatic lens and was the first to eliminate colour distortion. John Dollond was the first to patent this type of telescope for commercial production in 1758. Dollond’s patent was upheld above all others due to his ability to exploit the invention.

A Dollond telescope. Source: University of Arizona

For an interactive, and in-depth, timeline on the history of telescopes, visit Scientus.org

This piece of technology was a pivotal breakthrough in the field of astronomy. Astronomers had only their naked eyes to view the movements of stars and planets, but telescopes (astronomical and terrestrial) allowed both scholars and non-experts to revolutionize the study of astronomy.

Gran Telescopio Canarias (The Grand Canary Telescope) at the Roque de los Muchachos Observatory. Source: H. Raab

Telescopes are commercially available online, in stores that sell telescopes specifically, electronic stores, department stores and even wholesale/warehouse clubs. You can purchase a telescope for yourself that cost anywhere from a few dollars to upwards of $1000 depending on the specifications. This market has been successful because of the amount of money governments across the globe put into space exploration. Without telescopes available to people who aren’t working in space exploration, we would rely solely on the word and information they provide the public. Why not see the Moon or Mars for yourself?

Source: Ryan Wick