60 free Telescopes trivia questions with answers — science & nature quiz, new questions added Aug 2026.
Telescopes have been rewriting our picture of the universe for a little over four centuries. This quiz follows the whole story: the 1608 patent application by a Middelburg spectacle-maker, Galileo's leaden tube and the banquet where the word 'telescope' was coined, Kepler's improvement, Newton's first working reflector and the tarnishing metal mirrors that plagued astronomers for 200 years, the achromatic lens, the great refractors that ended with Yerkes, Herschel's forty-footer and the Leviathan of Parsonstown, then the mirror giants: Hooker, Hale, Keck, the Very Large Telescope and the 39-metre Extremely Large Telescope now rising in Chile. It also covers the other kinds of telescope: Jansky's merry-go-round and Grote Reber's backyard dish that started radio astronomy, Arecibo and China's FAST, the Event Horizon Telescope that photographed a black hole, and the space observatories from Hubble and Chandra to Kepler and James Webb. Easy questions ask what the two basic optical designs are and what the word means in Greek; harder ones get into speculum metal, Wolter mirrors, Ritchey–Chrétien optics and why nobody builds refractors bigger than a metre. It suits astronomy students, amateur observers, science teachers and quiz nights. Fans of Hubble specifically will also find our dedicated Hubble Space Telescope quiz. Every answer has been checked against the Wikipedia articles on telescopes, their history and the individual instruments named, and each question shows its source once you have answered.
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Q 01From which language do the roots of the word 'telescope' come, meaning 'far' and 'to look'?
Greek
Tele means 'far' and skopein 'to see'; Galileo himself had used the Latin word perspicillum in the Starry Messenger.
Q 02Who coined the word 'telescope' in 1611, at a banquet honouring Galileo at the Accademia dei Lincei?
Giovanni Demisiani
Demisiani was a Greek mathematician and poet; Prince Federico Cesi hosted the banquet to make Galileo a member of the academy.
Q 03In which country were the first known practical telescopes invented at the start of the 17th century?
The Netherlands
They were refracting telescopes with glass lenses, used for both terrestrial purposes and astronomy.
Q 04Which Middelburg spectacle-maker filed the earliest known telescope patent application in 1608?
Hans Lippershey
The patent was refused because others claimed the same invention, but the Dutch government paid him handsomely for copies of the instrument.
Q 05How did the October 1608 Dutch patent application describe the new instrument?
For seeing things far away as if they were nearby
A few weeks later another Dutch instrument-maker, Jacob Metius, also applied for a patent.
Q 06In which city did Galileo first hear of the 'Dutch perspective glass' in June 1609?
Venice
He said he worked out how to build one the first night after returning to Padua and made his first telescope the next day.
Q 07What combination of lenses did Galileo's telescope use?
Convex objective, concave eyepiece
The design gives an upright image but a narrow field of view; Kepler's convex-convex design gives a wider, inverted view.
Q 08Which astronomer described in 1611 a telescope with a convex objective and a convex eyepiece?
Johannes Kepler
The Keplerian design has a much larger field of view than Galileo's, but the image is upside down.
Q 09Using a Keplerian telescope he built himself, Christiaan Huygens discovered which moon in 1655?
Titan
Four years later his Systema Saturnium gave the first correct explanation of Saturn's ring, based on the same instrument.
Q 10What were the very long tubeless refractors built by 17th-century astronomers like Hevelius called?
Aerial telescopes
Long focal lengths reduced chromatic aberration; Adrien Auzout made instruments with focal lengths up to 600 feet.
Q 11Who built the first practical reflecting telescope in 1668?
Isaac Newton
Gregory had described a mirror telescope in 1663 but could not find an optician to build it; Hooke built the first Gregorian in 1673.
Q 12What tin-copper alloy was standard for telescope mirrors into the 19th century?
Speculum metal
It tarnished quickly and reflected poorly, so mirrors had to be re-polished and often re-figured.
Q 13What is the hallmark feature of a Newtonian telescope?
A diagonal mirror sending the image to a side eyepiece
Q 21Which French physicist introduced the process of silvering glass mirrors for telescopes in 1857?
Léon Foucault
Aluminised coatings, which last far longer, followed in 1932.
Q 22In which US state is Yerkes Observatory, home to the world's largest refracting telescope when it opened in 1897?
Wisconsin
It was shown at Chicago's World's Columbian Exposition before installation at Williams Bay; the observatory was founded by George Ellery Hale.
Q 23Roughly what is the practical maximum diameter for a refracting telescope's lens?
About 1 metre
Which is why virtually every large research telescope built since 1900 has been a reflector.
The flat secondary reflects the light at 90 degrees near the primary mirror's focus.
Q 14In 1672 Laurent Cassegrain described a reflector in which light passes through what?
A central hole in the main mirror
A small convex secondary mirror sends the light back through the hole; the Ritchey–Chrétien variant is used by Hubble.
Q 15Which Englishman built the first achromatic-lens telescope in 1733 but never publicised it?
Chester Moore Hall
Dollond learned of the invention and produced achromatic telescopes commercially from 1758; a court case later admitted Hall was the first inventor.
Q 16What did an achromatic lens combine to bring red and blue light to the same focus?
Two lenses of different kinds of glass
Euler had even proposed an objective of glass and water; Dollond disputed his theory but built the practical version.
Q 17John Hadley, better known for inventing the octant, advanced reflecting telescopes in 1721 by doing what?
Making precision parabolic speculum mirrors
His 6-inch reflector matched a 7.5-inch aerial telescope in tests at the Royal Society, showing Newton's idea worked in practice.
Q 18William Herschel began grinding telescope mirrors around 1774 while working in Bath as what?
A music teacher
By 1789 he had built his 40-foot telescope with a 49-inch mirror at Observatory House in Slough.
Q 19In the 'Herschelian' design, how did Herschel avoid the light loss caused by a diagonal secondary?
He tilted the primary and viewed the image directly
Speculum mirrors reflected so poorly that removing the diagonal made a real difference in brightness.
Q 20Who built the 72-inch 'Leviathan of Parsonstown', the world's largest telescope from 1845 to 1917?
William Parsons, 3rd Earl of Rosse
Built at Birr Castle in Ireland, it revealed the spiral form of galaxies.
Q 24The 100-inch Hooker telescope, the world's largest from 1917 to 1949, is on which California mountain?
Mount Wilson
Edwin Hubble used it to show that nebulae lay far beyond the Milky Way and that the universe is expanding.
Q 25The 200-inch Hale Telescope at Palomar has a primary mirror made of which glass?
Pyrex
Corning Glass Works cast the honeycomb, low-expansion disc; the telescope saw first light in January 1949 under Edwin Hubble.
Q 26Which telescope ended the Hale Telescope's reign as the world's largest in 1976?
The Soviet BTA-6
Hale then remained the second largest until Keck 1 in Hawaii in 1993.
Q 27What is the general term for a telescope that uses both mirrors and lenses to form its image?
Catadioptric
The Schmidt camera, invented by Bernhard Schmidt in 1930, is a famous wide-field example.
Q 28Who invented the simple alt-azimuth reflector beloved of amateur astronomers, the Dobsonian, in 1956?
John Dobson
It is essentially a Newtonian on a plywood box mount.
Q 29Which Bell Labs engineer first detected radio waves from space in 1932?
Karl Jansky
He had been asked to find sources of static that might interfere with radiotelephone service.
Q 30Where did radio amateur Grote Reber build the first purpose-built radio telescope in 1937?
In his back yard in Wheaton, Illinois
The sky survey he made with it is often considered the beginning of radio astronomy.