A 1666 Mexico manuscript linked to Galileo Galilei may challenge the accepted history of the telescope. The document describes a sophisticated four-lens instrument and says Galileo made it. If the attribution is correct, he experimented with this type of telescope more than a decade earlier than historians have generally believed.
José María Moreno Madrid, a researcher at the University of Limerick in Ireland, identified the account while studying a 17th-century manuscript held at the National Library of Spain. His analysis was published in the journal “Annals of Science.”
The manuscript was written by Spanish Dominican friar Ignacio Muñoz. It contains a section titled “On Star Telescopes,” which provides a detailed description of a four-lens terrestrial telescope. Muñoz states that the instrument was “made by Galileo.”
The claim could shift the timeline of early telescope development. Questions about the history of optical instruments extend much further back, including debate over whether the ancient Greeks had technology resembling telescopes.
Four-lens telescope appeared earlier than expected
Galileo is best known for improving a simpler telescope that combined a convex objective lens with a concave eyepiece. He turned improved versions toward the sky in 1609, making observations that helped transform astronomy.
Muñoz described something more complex. The instrument used four lenses and produced an upright image, making it especially useful for viewing objects on Earth.
Historians have generally dated the first four-lens telescopes to around 1643 to 1645. The manuscript could push experimentation with the design back to 1630 or earlier.
Moreno Madrid argues that, if the attribution is correct, Galileo would become the earliest known experimenter with this four-lens configuration.
The document also contains unusually detailed drawings. Muñoz recorded the telescope’s optical components, distances between lenses, and tube lengths. Such evidence is rare for early scientific instruments. Other devices, including the astrolabe, played important roles in astronomy and navigation long before telescopes appeared.
Scientific test in Mexico City
Muñoz produced the description under unusual circumstances. He had been exiled to Portuguese India after attempting to establish a Dominican order in the Philippines without authorization. He later proposed a new nautical method to Spain’s King Philip IV and sought royal support for his journey home.
A 1666 manuscript from Mexico City may rewrite the history of Galileo’s telescope.
The document describes a sophisticated four-lens instrument said to have been made by Galileo, potentially pushing the technology back more than a decade. pic.twitter.com/JbFFhCYS6K
— Tom Marvolo Riddle (@tom_riddle2025) September 4, 2026
His travels eventually brought him to Mexico City in New Spain. Viceroy Antonio Sebastián de Toledo Molina y Salazar, Marquis of Mancera, apparently doubted Muñoz’s scientific abilities. He gave the friar a telescope and asked him to analyze it. Muñoz responded with the detailed technical account now being studied.
Galileo’s links to the Spanish court
Moreno Madrid proposes that the telescope may have reached Mexico through the Spanish royal court. Between 1618 and 1631, Galileo sought support from the Spanish monarchy for his proposed method of determining longitude at sea. He believed observations of eclipses involving Jupiter’s moons could help sailors determine their position.
Historical evidence shows Galileo sent three telescopes to King Philip IV and the queen. Moreno Madrid suggests the instrument examined by Muñoz could have been one of them and may later have reached Mancera through his royal connections.
The theory remains unconfirmed. No known correspondence between Mancera and the Spanish court mentions the telescope. Muñoz’s statement therefore remains the central evidence connecting the instrument to Galileo.
The finding nevertheless fits into a much longer history of attempts to understand the heavens. Greek thinkers such as Aristarchus developed sophisticated astronomical ideas centuries earlier, helping lay foundations for the development of astronomy that eventually reached Galileo.
Rare evidence of early telescope technology
Only a small number of telescopes from the first half of the 17th century survive, and securely identifying instruments made by Galileo remains difficult.
Galileo also left no detailed technical account explaining how he constructed his telescopes. That makes Muñoz’s description potentially significant.
If researchers eventually confirm the attribution, the manuscript could provide the most detailed surviving technical description of a telescope made by Galileo. It could also push the history of four-lens telescope experimentation back by more than a decade.
For now, the manuscript provides intriguing evidence rather than proof. Further discoveries in Spanish or Mexican archives could help establish whether a little-known Galileo telescope really reached Mexico City more than 350 years ago.
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