Galileo ver­sus the Church

From experiments to in­qui­si­tion, dis­cover the Re­nais­sance sci­en­tist’s iconic clash with the pope and how he proved that the Earth goes around the Sun

All About History - - CON­TENTS - Writ­ten by Jes­sica Leggett

In­side the Re­nais­sance sci­en­tist’s iconic clash with the pope

Galileo Galilei was never des­tined for a life as an as­tronomer and physi­cist. Iron­i­cally, he at­tended school at the lo­cal monastery and after this had been well on his way for a fu­ture as a doc­tor. His fa­ther, Vin­cen­zio, had high hopes for his son and ar­ranged for him to study medicine at the Univer­sity of Pisa from 1581. In spite of this, Galileo never cared for bi­ol­ogy, devel­op­ing a far greater in­ter­est in phi­los­o­phy and math­e­mat­ics. Against the protes­ta­tions of his fa­ther, he promptly switched sub­jects and never looked back.

Study­ing hard for four years, Galileo left univer­sity with­out a de­gree and turned his hand to pri­vate tu­tor­ing. Dur­ing this time he wrote his short trea­tise, Cos­mog­ra­phy, which he used to teach his stu­dents about the mys­te­ri­ous ce­les­tial bod­ies.

Cos­mog­ra­phy ad­hered to the widely ac­cepted, tra­di­tional geo­cen­tric philoso­phies of Aris­to­tle and Ptolemy, which placed the Earth at the cen­tre of the uni­verse.

He soon moved on from his tu­tor­ing ca­reer and re­turned to the Univer­sity of Pisa in 1589, where he spent the next three years as the pro­fes­sor of math­e­mat­ics. It is likely that this is when he suc­ceeded in dis­prov­ing Aris­to­tle’s the­ory that ob­jects of dif­fer­ent mass fall at dif­fer­ent speeds, though whether Galileo ac­tu­ally tested this by drop­ping balls of the Lean­ing Tower of Pisa is dis­puted as the only record we have of it is a bi­og­ra­phy writ­ten by his pupil Vin­cenzo Vi­viani in 1717.

Un­for­tu­nately, his un­con­ven­tional be­liefs made Galileo un­pop­u­lar so his con­tract at the univer­sity was not re­newed. He moved once again in 1592 and trav­elled north to Padua, where he as­sumed a new, higher paid po­si­tion as a pro­fes­sor of math­e­mat­ics at the city’s univer­sity. Here, Galileo re­ally be­gan to hone his re­search. He con­ducted a num­ber of experiments, many of which were in the field of me­chan­ics.

Start­ing in 1602, he made some of the first sci­en­tific ob­ser­va­tions re­gard­ing pen­du­lums. He also un­cov­ered the prin­ci­ple of isochro­nism, where a pen­du­lum would take the same time to com­plete a swing re­gard­less of how big that swing was. Ul­ti­mately, this led to the in­ven­tion of the ac­cu­rate me­chan­i­cal clock in 1656 – a de­vice hu­man­ity came to rely on.

After a few years of ded­i­cat­ing his time to his experiments, ev­ery­thing changed. In 1609, Galileo heard ru­mours that a de­vice that could make dis­tant ob­jects ap­pear close had been in­vented in the Nether­lands: the tele­scope. Once he learned that it had been sim­ply made with just a tube and a lens on both ends, he im­me­di­ately set out to re-cre­ate one for him­self. His ini­tial ver­sions ranged in mag­ni­fy­ing power, up to eight times, but by 1610, he had de­vel­oped a tele­scope that could be mag­ni­fied 20 times – far more pow­er­ful than the orig­i­nal, rudi­men­tary in­ven­tion.

Armed with his tele­scope, the pos­si­bil­i­ties open to Galileo were end­less. Just be­tween 1609 and 1610 alone, he dis­cov­ered moun­tains on the Moon, the four satel­lites of Jupiter and nu­mer­ous stars in the Milky Way. He ob­served the dif­fer­ent phases of Venus and, mis­tak­enly, be­lieved that he had found two ‘ears’ that ac­com­pa­nied Saturn. Al­though he did not re­alise it, Galileo had ac­tu­ally ob­served Saturn’s iconic ring, which would first be con­firmed in 1656.


Galileo’s ce­les­tial dis­cov­er­ies, cou­pled with his math­e­mat­i­cal ge­nius, placed him light years ahead of his con­tem­po­raries. His sud­den fame came at a time when the Coper­ni­can Rev­o­lu­tion was al­ready well un­der­way. Back in 1543, Ni­co­laus Coper­ni­cus pub­lished On the Rev­o­lu­tion of Heav­enly Spheres, which ar­gued that the Sun, not the Earth, was at the cen­tre of the uni­verse. This the­ory be­came known as ‘he­lio­cen­trism’ (from the Greek ‘hēlios’ mean­ing ‘sun’), and con­tra­dicted the no­tion that the uni­verse re­volved around our planet, or geo­cen­trism (from

‘gē’ mean­ing ‘Earth’). As Galileo was mak­ing his own ce­les­tial ob­ser­va­tions, Ger­man as­tronomer Jo­hannes Ke­pler was also con­duct­ing sig­nif­i­cant re­search in the field.

Ke­pler’s Astrono­mia Nova was pub­lished in 1609 after his decade-long re­search into the mo­tion of Mars. One of the most mo­men­tous works to ever grace the world of sci­ence, not only did Ke­pler con­clude that or­bital paths were el­lip­ti­cal and not cir­cu­lar, he also ar­gued that his find­ings sup­ported he­lio­cen­trism. With his tele­scope, Galileo’s revo­lu­tion­ary re­search was about to prove that Coper­ni­can­ism was not just a hy­poth­e­sis – it was re­al­ity.

Galileo de­cided to share his new dis­cov­er­ies, start­ing with his book Sidereus Nun­cius in 1610. Also known by its English name, Starry Mes­sen­ger, it drew a lot of in­ter­est and raised his celebrity pro­file to new heights. That same year, he was ap­pointed to the pres­ti­gious po­si­tion of court math­e­ma­ti­cian to Cosimo II de’ Medici, Grand Duke of Tus­cany, one of his for­mer pupils. How­ever, Starry Mes­sen­ger also at­tracted a lot of crit­i­cism. Galileo’s con­clu­sion that it was the Sun at the cen­tre of the uni­verse was not ac­cepted by the Catholic Church, the most pow­er­ful in­sti­tu­tion in Italy – it stead­fastly sup­ported the tra­di­tional geo­cen­tric views of Aris­to­tle and Ptolemy.

But all was not yet lost for Galileo. He was not con­fronted with to­tal op­po­si­tion to his as­tro­nom­i­cal find­ings – for in­stance, Je­suit as­tronomers man­aged to re­peat his ob­ser­va­tions them­selves. Galileo even had a few ad­mir­ers from the Church, most no­tably Car­di­nal Maf­feo Bar­berini. De­spite be­ing faced

“Galileo re­fused to back down”

with all the ev­i­dence, the Church re­fused to rec­on­cile with the Coper­ni­can model. Some as­tronomers within the Church, such as the Je­suits, ad­vo­cated the Ty­chonic sys­tem, de­vel­oped by as­tronomer Ty­cho Brahe, which math­e­mat­i­cally sup­ported Galileo’s re­search but also main­tained the sta­tus quo. Ac­cord­ing to Brahe, the Sun and Moon re­volved around the Earth but the other plan­ets or­bited the Sun – a mix of the two the­o­ries.

In­fin­itely frus­trated that his ev­i­dence was be­ing ig­nored, Galileo re­fused to back down. He cam­paigned in­ces­santly in favour of Coper­ni­cus’ the­o­ries and clashed with the­olo­gians, who des­per­ately clung to their geo­cen­tric views. Even though he pro­voked at­ten­tion, his com­bat­ive be­hav­iour back­fired and the Je­suits turned their back on him. Now the Catholic Church de­cided that they had let Galileo run wild long enough – it was time to put its foot down.

What fol­lowed was one of the most mo­men­tous events in his­tory re­gard­ing the ten­ta­tive re­la­tion­ship be­tween religion and sci­ence: the ‘Galileo Af­fair’. In 1616, the Ro­man Catholic In­qui­si­tion in­ves­ti­gated Galileo’s work, for which he was be­ing ac­cused of heresy. A group of the­olo­gians were asked to as­sess the the­ory of he­lio­cen­trism that Galileo had so de­fi­antly de­fended and whether it held any merit.

Of course, the the­olo­gians’ pri­mary task was the de­fence of the Catholic Church and the Bi­ble and less than a week later, the judge­ment was passed. They an­nounced that he­lio­cen­trism con­tra­dicted the Holy Scrip­tures and thus Coper­ni­can­ism amounted to heresy. No sooner had the ver­dict been de­liv­ered than Galileo was ordered to stop his sup­port for the the­ory and all works as­so­ci­ated with it, in­clud­ing his, were banned pend­ing suit­able cor­rec­tions. In­stead of get­ting ac­cep­tance, Galileo had been left with dis­as­ter.

ABOVE This paint­ing de­picts Galileo teach­ing a stu­dent while work­ing at the Univer­sity of Padua

Galileo’s draw­ings of the phases and sur­face of the Moon from Sidereus Nun­cius, 1610 BE­LOW

A replica based on Galileo’s de­sign for a pen­du­lum clock ABOVE


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