GANYMEDE, CALLISTO, IO & EUROPA; GALILEAN MOONS

Today, The Grandma has received the wonderful visit of her closer friend Joseph de Ca'th Lon, who is a fan of History, Science and Astronomy. They kave been talking about the Galilean moons, that were firstly observed by Galileo Galilei on a day like today in 1610.

The Galilean moons, or Galilean satellites, are the four largest moons of Jupiter: Io, Europa, Ganymede, and Callisto.

They are the most readily visible Solar System objects after the unaided visible Saturn, the dimmest of the classical planets, allowing observation with common binoculars, even under night sky conditions of high light pollution.

The invention of the telescope enabled the discovery of the moons in 1610. Through this they became the first Solar System objects discovered since humans have started tracking the classical planets, and the first objects to be found to orbit a planet other than the Earth.

They are planetary-mass moons and among the largest objects in the Solar System; Titan and Triton, together with the Moon, are larger than any of the Solar System's dwarf planets. 

The largest of the four is Ganymede, which is the largest moon in the Solar System, and Callisto, both of which are either larger or almost as large as the planet Mercury, though not nearly as massive. The smaller ones, Io and Europa, are about the size of the Moon. 

The three inner moons -Io, Europa, Ganymede- are in a 4:2:1 orbital resonance with each other. While the Galilean moons are spherical, all of Jupiter's remaining moons have irregular forms because of their weaker self-gravitation, in addition to being much smaller.

The Galilean moons are named after Galileo Galilei, who observed them in either December 1609 or January 1610, and recognized them as satellites of Jupiter in March 1610; they remained the only known moons of Jupiter until the discovery of the fifth largest moon of Jupiter Amalthea in 1892.

Galileo initially named his discovery the Cosmica Sidera (Cosimo's stars) or Medicean Stars, but the names that eventually prevailed were chosen by Simon Marius. 

Marius discovered the moons independently at nearly the same time as Galileo, 8 January 1610, and gave them their present individual names, after mythological characters that Zeus seduced or abducted, which were suggested by Johannes Kepler in his Mundus Jovialis, published in 1614.

Their discovery showed the importance of the telescope as a tool for astronomers by proving that there were objects in space that cannot be seen by the naked eye. The discovery of celestial bodies orbiting something other than Earth dealt a serious blow to the then-accepted Ptolemaic world system, a geocentric theory in which everything orbits around Earth.

As a result of improvements Galileo Galilei made to the telescope, with a magnifying capability of 20×, he was able to see celestial bodies more distinctly than was previously possible. This allowed Galileo to observe in either December 1609 or January 1610 what came to be known as the Galilean moons.

More information: The Planetary Society

On 7 January 1610, Galileo wrote a letter containing the first mention of Jupiter's moons. At the time, he saw only three of them, and he believed them to be fixed stars near Jupiter. He continued to observe these celestial orbs from 8 January to 2 March 1610. In these observations, he discovered a fourth body, and also observed that the four were not fixed stars, but rather were orbiting Jupiter.

Galileo's discovery proved the importance of the telescope as a tool for astronomers by showing that there were objects in space to be discovered that until then had remained unseen by the naked eye. More importantly, the discovery of celestial bodies orbiting something other than Earth dealt a blow to the then-accepted Ptolemaic world system, which held that Earth was at the center of the universe and all other celestial bodies revolved around it.

Galileo's 13 March 1610, Sidereus Nuncius (Starry Messenger), which announced celestial observations through his telescope, does not explicitly mention Copernican heliocentrism, a theory that placed the Sun at the center of the universe. Nevertheless, Galileo accepted the Copernican theory.

A Chinese historian of astronomy, Xi Zezong, has claimed that a small reddish star observed near Jupiter in 364 BCE by Chinese astronomer Gan De may have been Ganymede. If true, this might predate Galileo's discovery by around two millennia.

The observations of Simon Marius are another noted example of observation, and he later reported observing the moons in 1609. However, because he did not publish these findings until after Galileo, there is a degree of uncertainty around his records.

The names that eventually prevailed were chosen by Simon Marius, who discovered the moons independently at the same time as Galileo: he named them at the suggestion of Johannes Kepler after lovers of the god Zeus (the Greek equivalent of Jupiter), in his Mundus Jovialis, published in 1614:

Jupiter is much blamed by the poets on account of his irregular loves. Three maidens are especially mentioned as having been clandestinely courted by Jupiter with success. Io, daughter of the River Inachus, Callisto of Lycaon, Europa of Agenor. Then there was Ganymede, the handsome son of King Tros, whom Jupiter, having taken the form of an eagle, transported to heaven on his back, as poets fabulously tell... I think, therefore, that I shall not have done amiss if the First is called by me Io, the Second Europa, the Third, on account of its majesty of light, Ganymede, the Fourth Callisto... This fancy, and the particular names given, were suggested to me by Kepler, Imperial Astronomer, when we met at Ratisbon fair in October 1613. So if, as a jest, and in memory of our friendship then begun, I hail him as joint father of these four stars, again I shall not be doing wrong.

More information: NASA

We cannot teach people anything;
we can only help them discover it
within themselves.

Galileo Galilei

GALILEO GALILEI, "EPPUR SI MUOVE / AND YET IT MOVES"

Università di Pisa

Today, Joseph de Ca'th Lon and his friends have visited the University of Pisa, one of the most prestigious centres of knowledge and studies in Europe. Joseph likes Astronomy and Science in general and he has wanted to discover new information about Galileo Galilei the great figure of the 16th and 17th centuries.
 

Galileo Galilei (15 February 1564-8 January 1642) was a Tuscan astronomer, physicist and engineer, sometimes described as a polymath. Galileo has been called the father of observational astronomy, the father of modern physics, the father of the scientific method, and the father of modern science.

Galileo studied speed and velocity, gravity and free fall, the principle of relativity, inertia, projectile motion and also worked in applied science and technology, describing the properties of pendulums and hydrostatic balances, inventing the thermoscope and various military compasses, and using the telescope for scientific observations of celestial objects.

His contributions to observational astronomy include the telescopic confirmation of the phases of Venus, the observation of the four largest satellites of Jupiter, the observation of Saturn and the analysis of sunspots.

Galileo Gallilei

Galileo's championing of heliocentrism and Copernicanism was controversial during his lifetime, when most subscribed to geocentric models such as the Tychonic system. He met with opposition from astronomers, who doubted heliocentrism because of the absence of an observed stellar parallax. The matter was investigated by the Roman Inquisition in 1615, which concluded that heliocentrism was foolish and absurd in philosophy, and formally heretical since it explicitly contradicts in many places the sense of Holy Scripture.

Galileo later defended his views in Dialogue Concerning the Two Chief World Systems (1632), which appeared to attack Pope Urban VIII and thus alienated him and the Jesuits, who had both supported Galileo up until this point. He was tried by the Inquisition, found vehemently suspect of heresy, and forced to recant. He spent the rest of his life under house arrest. While under house arrest, he wrote Two New Sciences, in which he summarized work he had done some forty years earlier on the two sciences now called kinematics and strength of materials.

Galileo was born in Pisa, then part of the Duchy of Florence, on 15 February 1564, the first of six children of Vincenzo Galilei, a famous lutenist, composer, and music theorist, and Giulia, who had married in 1562.

More information: National Institutes of Health-US NLM

Galileo became an accomplished lutenist himself and would have learned early from his father a scepticism for established authority, the value of well-measured or quantified experimentation, an appreciation for a periodic or musical measure of time or rhythm, as well as the results expected from a combination of mathematics and experiment.

When Galileo Galilei was eight, his family moved to Florence, but he was left with Jacopo Borghini for two years. He was educated from 1575 to 1578 in the Vallombrosa Abbey, about 30 km southeast of Florence.

Galileo Galilei

Although Galileo seriously considered the priesthood as a young man, at his father's urging he instead enrolled in 1580 at the University of Pisa for a medical degree.

In 1581, when he was studying medicine, he noticed a swinging chandelier, which air currents shifted about to swing in larger and smaller arcs.

To him, it seemed, by comparison with his heartbeat, that the chandelier took the same amount of time to swing back and forth, no matter how far it was swinging. When he returned home, he set up two pendulums of equal length and swung one with a large sweep and the other with a small sweep and found that they kept time together. It was not until the work of Christiaan Huygens, almost one hundred years later, that the tautochrone nature of a swinging pendulum was used to create an accurate timepiece.

Up to this point, Galileo had deliberately been kept away from mathematics, since a physician earned a higher income than a mathematician. However, after accidentally attending a lecture on geometry, he talked his reluctant father into letting him study mathematics and natural philosophy instead of medicine. He created a thermoscope, a forerunner of the thermometer, and, in 1586, published a small book on the design of a hydrostatic balance he had invented, which first brought him to the attention of the scholarly world.

More information: Sciencing

Galileo also studied disegno, a term encompassing fine art, and, in 1588, obtained the position of instructor in the Accademia delle Arti del Disegno in Florence, teaching perspective and chiaroscuro. Being inspired by the artistic tradition of the city and the works of the Renaissance artists, Galileo acquired an aesthetic mentality. While a young teacher at the Accademia, he began a lifelong friendship with the Florentine painter Cigoli, who included Galileo's lunar observations in one of his paintings.

In 1589, he was appointed to the chair of mathematics in Pisa. In 1591, his father died, and he was entrusted with the care of his younger brother Michelagnolo. In 1592, he moved to the University of Padua where he taught geometry, mechanics, and astronomy until 1610.

The Dialogue by Galileo Galilei

During this period, Galileo made significant discoveries in both pure fundamental science, for example, kinematics of motion and astronomy, as well as practical applied science, for example, strength of materials and pioneering the telescope.

His multiple interests included the study of astrology, which at the time was a discipline tied to the studies of mathematics and astronomy.

In the whole world prior to Galileo's conflict with the Church, the majority of educated people subscribed either to the Aristotelian geocentric view that the earth was the center of the universe and that all heavenly bodies revolved around the Earth, or the Tychonic system that blended geocentrism with heliocentrism.

More information: Space

On February 19, 1616, the Inquisition asked a commission of theologians, known as qualifiers, about the propositions of the heliocentric view of the universe.

In 1633 Galileo was ordered to stand trial on suspicion of heresy. He was interrogated while threatened with physical torture.

Galileo was found guilty, and the sentence of the Inquisition, issued on 22 June 1633.

According to popular legend, after recanting his theory that the Earth moved around the Sun, Galileo allegedly muttered the rebellious phrase And yet it moves"

It was while Galileo was under house arrest that he dedicated his time to one of his finest works, Two New Sciences. Here he summarised work he had done some forty years earlier, on the two sciences now called kinematics and strength of materials, published in Holland to avoid the censor.

Galileo continued to receive visitors until 1642, when, after suffering fever and heart palpitations, he died on 8 January 1642, aged 77.

The Grand Duke of Tuscany, Ferdinando II, wished to bury him in the main body of the Basilica of Santa Croce, next to the tombs of his father and other ancestors, and to erect a marble mausoleum in his honour.

More information: Galileo Galilei to trial against the Inquisition

Who would set a limit to the mind of man?

Who would dare assert that we know all there is to be known?

Galileo Galilei

PISA, THE AGE OF THE REPUBLIC & THE LEANING TOWER

The Grandma & Claire visit Pisa, Tuscany

Today, Claire Fontaine and her friends have visited Pisa, one of the most beautiful cities in Tuscany. Pisa is well-known thanks to its Leaning Tower and its inhabitants like Galileo Galilei.

Pisa is a city and comune in Tuscany, straddling the Arno just before it empties into the Ligurian Sea. It is the capital city of the Province of Pisa. Although Pisa is known worldwide for its leaning tower, the bell tower of the city's cathedral, the city contains more than 20 other historic churches, several medieval palaces, and various bridges across the Arno. Much of the city's architecture was financed from its history as one of the Italian maritime republics.

The city is also home of the University of Pisa, which has a history going back to the 12th century and also has the Scuola Normale Superiore di Pisa, founded by Napoleon in 1810, and its offshoot, the Sant'Anna School of Advanced Studies, as the best-sanctioned Superior Graduate Schools in Italy.

More information: Visit Tuscany  

The origin of the name, Pisa, is a mystery. While the origin of the city had remained unknown for centuries, the Pelasgi, the Greeks, the Etruscans, and the Ligurians had variously been proposed as founders of the city, for example, a colony of the ancient city of Pisa, Greece.

Archaeological remains from the fifth century BC confirmed the existence of a city at the sea, trading with Greeks and Gauls.

The presence of an Etruscan necropolis, discovered during excavations in the Arena Garibaldi in 1991, confirmed its Etruscan origins.

Ancient Roman authors referred to Pisa as an old city. Strabo referred Pisa's origins to the mythical Nestor, king of Pylos, after the fall of Troy. Virgil, in his Aeneid, states that Pisa was already a great center by the times described; the settlers from the Alpheus coast have been credited with the founding of the city in the Etruscan lands.

Joseph & Jordi visit the Leaning Tower of Pisa

During the last years of the Western Roman Empire, Pisa did not decline as much as the other cities of Italy, probably due to the complexity of its river system and its consequent ease of defence. In the seventh century, Pisa helped Pope Gregory I by supplying numerous ships in his military expedition against the Byzantines of Ravenna: Pisa was the sole Byzantine centre of Tuscia to fall peacefully in Lombard hands, through assimilation with the neighbouring region where their trading interests were prevalent. Pisa began in this way its rise to the role of main port of the Upper Tyrrhenian Sea.

After Charlemagne had defeated the Lombards under the command of Desiderius in 774, Pisa went through a crisis, but soon recovered.

The power of Pisa as a maritime nation began to grow and reached its apex in the 11th century, when it acquired traditional fame as one of the four main historical maritime republics of Italy (Repubbliche Marinare).

More information: Discover Tuscany

In 1113, Pisa and Pope Paschal II set up, together with the count of Barcelona and other contingents from Provence and Italy, Genoese excluded, a war to free the Balearic Islands from the Moors; the queen and the king of Majorca were brought in chains to Tuscany.

Though the Almoravides soon reconquered the island, the booty taken helped the Pisans in their magnificent programme of buildings, especially the cathedral, and Pisa gained a role of pre-eminence in the Western Mediterranean.

In 1238, Pope Gregory IX formed an alliance between Genoa and Venice against the empire, and consequently against Pisa, too.

The great expansion in the Mediterranean and the prominence of the merchant class urged a modification in the city's institutes. The system with consuls was abandoned, and in 1230, the new city rulers named a capitano del popolo, people's chieftain, as civil and military leader. In spite of these reforms, the conquered lands and the city itself were harassed by the rivalry between the two families of Della Gherardesca and Visconti.

 

Tonyi Tamaki visits the Leaning Tower of Pisa

The decline is said to have begun on August 6, 1284, when the numerically superior fleet of Pisa, under the command of Albertino Morosini, was defeated by the brilliant tactics of the Genoese fleet, under the command of Benedetto Zaccaria and Oberto Doria, in the dramatic naval Battle of Meloria. Furthermore, in the 15th century, access to the sea became more and more difficult, as the port was silting up and was cut off from the sea.

When in 1494, Charles VIII of France invaded the Italian states to claim the Kingdom of Naples, Pisa grabbed the opportunity to reclaim its independence as the Second Pisan Republic.

Pisa acquired a mainly cultural role spurred by the presence of the University of Pisa, created in 1343, and later reinforced by the Scuola Normale Superiore di Pisa (1810) and Sant'Anna School of Advanced Studies (1987).

The Leaning Tower of Pisa, in Italian Torre pendente di Pisa, or simply the Tower of Pisa is the campanile, or freestanding bell tower, of the cathedral of the Italian city of Pisa, known worldwide for its nearly four-degree lean, the result of an unstable foundation. The tower is situated behind the Pisa Cathedral and is the third oldest structure in the city's Cathedral Square (Piazza del Duomo), after the cathedral and the Pisa Baptistry.

More information: Love from Tuscany

The tower's tilt began during construction in the 12th century, due to soft ground on one side, which was unable to properly support the structure's weight. The tilt increased in the decades before the structure was completed in the 14th century. It gradually increased until the structure was stabilized, and the tilt partially corrected, by efforts in the late 20th and early 21st centuries.

The height of the tower is 55.86 metres from the ground on the low side and 56.67 metres on the high side. The width of the walls at the base is 2.44 m. Its weight is estimated at 14,500 metric tons. The tower has 296 or 294 steps; the seventh floor has two fewer steps on the north-facing staircase.

In 1990 the tower leaned at an angle of 5.5 degrees, but following remedial work between 1993 and 2001 this was reduced to 3.97 degrees, reducing the overhang by 45 cm at a cost of £200m. It lost a further 4 cm of tilt in the two decades to 2018.

There has been controversy about the real identity of the architect of the Leaning Tower of Pisa. For many years, the design was attributed to Guglielmo and Bonanno Pisano, a well-known 12th-century resident artist of Pisa, known for his bronze casting, particularly in the Pisa Duomo. 

Pisano left Pisa in 1185 for Monreale, Sicily, only to come back and die in his home town. A piece of cast bearing his name was discovered at the foot of the tower in 1820, but this may be related to the bronze door in the façade of the cathedral that was destroyed in 1595.

A 2001 study seems to indicate Diotisalvi was the original architect, due to the time of construction and affinity with other Diotisalvi works, notably the bell tower of San Nicola and the Baptistery, both in Pisa.

More information: Tower of Pisa

Construction of the tower occurred in three stages over 199 years. Work on the ground floor of the white marble campanile began on August 14, 1173 during a period of military success and prosperity. This ground floor is a blind arcade articulated by engaged columns with classical Corinthian capitals.

The tower began to sink after construction had progressed to the second floor in 1178. This was due to a mere three-metre foundation, set in weak, unstable subsoil, a design that was flawed from the beginning. Construction was subsequently halted for almost a century, because the Republic of Pisa was almost continually engaged in battles with Genoa, Lucca, and Florence. This allowed time for the underlying soil to settle.

Numerous efforts have been made to restore the tower to a vertical orientation or at least keep it from falling over. Most of these efforts failed; some worsened the tilt.

In May 2008, engineers announced that the tower had been stabilized such that it had stopped moving for the first time in its history. They stated that it would be stable for at least 200 years.

More information: Walks of Italy

 

 I gave birth to our daughter Coco in Pisa,

and it was a wonderful time in all our lives.

Trudie Styler

GALILEO GALILEI TO TRIAL AGAINST THE INQUISITION

Galileo Galilei

February, 13 1633. Galileo Galilei arrives in Rome for his trial before the Inquisition. This trial changes the History. It is a fight between a man and a great power, a fight between reason, logic and knowledge against Inquisition.

February, 13 2019. The History repeats. A new fight between democratic ideas and dark forces, which want to keep their power over population, economy and politic power, is happening.

The Grandma wants to talk about the great figure of Galileo Galilei, a man who changed the line of the History. Before talking about Galileo, The Grandma has studied a new lesson of her Intermediate Language Practice (Grammar 3).

More information: Present Time 2

The Galileo affair, in Italian Il processo a Galileo Galilei, was a sequence of events, beginning around 1610, culminating with the trial and condemnation of Galileo Galilei by the Roman Catholic Inquisition in 1633 for his support of heliocentrism.

In 1610, Galileo published his Sidereus Nuncius, describing the surprising observations that he had made with the new telescope, namely the phases of Venus and the Galilean moons of Jupiter. With these observations he promoted the heliocentric theory of Nicolaus Copernicus, published in De revolutionibus orbium coelestium in 1543.

More information: Famous Trials

Galileo's initial discoveries were met with opposition within the Catholic Church, and in 1616 the Inquisition declared heliocentrism to be formally heretical.

Galileo with some students

Heliocentric books were banned and Galileo was ordered to refrain from holding, teaching or defending heliocentric ideas.

Galileo went on to propose a theory of tides in 1616, and of comets in 1619; he argued that the tides were evidence for the motion of the Earth. In 1632 Galileo, now an old man, published his Dialogue Concerning the Two Chief World Systems, which implicitly defended heliocentrism, and was immensely popular. Responding to mounting controversy over theology, astronomy and philosophy, the Roman Inquisition tried Galileo in 1633 and found him vehemently suspect of heresy, sentencing him to indefinite imprisonment. Galileo was kept under house arrest until his death in 1642.

Galileo's contributions caused difficulties for theologians and natural philosophers of the time, as they contradicted scientific and philosophical ideas based on those of Aristotle and Ptolemy and closely associated with the Catholic Church. In particular, Galileo's observations of the phases of Venus, which showed it to circle the Sun, and the observation of moons orbiting Jupiter, contradicted the geocentric model of Ptolemy, which was backed and accepted by the Roman Catholic Church, and supported the Copernican model advanced by Galileo.

More information: UCLA

Tommaso Caccini, a Dominican friar, appears to have made the first dangerous attack on Galileo. Caccini arrived at the Inquisition's offices in Rome to denounce Galileo for his Copernicanism and various other alleged heresies supposedly being spread by his pupils.

On February 19, 1616, the Inquisition asked a commission of theologians, known as qualifiers, about the propositions of the heliocentric view of the universe.

The papal Congregation of the Index preferred a stricter prohibition, and so with the Pope's approval, on March 5 the Congregation banned all books advocating the Copernican system, which it called the false Pythagorean doctrine, altogether contrary to Holy Scripture.

The Trial of Galileo

With the loss of many of his defenders in Rome because of Dialogue Concerning the Two Chief World Systems, in 1633 Galileo was ordered to stand trial on suspicion of heresy for holding as true the false doctrine taught by some that the sun is the center of the world.

Galileo was interrogated while threatened with physical torture. Galileo was found guilty, and the sentence of the Inquisition, issued on 22 June 1633, was in three essential parts:

-Galileo was found vehemently suspect of heresy, namely of having held the opinions that the Sun lies motionless at the center of the universe, that the Earth is not at its centre and moves, and that one may hold and defend an opinion as probable after it has been declared contrary to Holy Scripture. He was required to abjure, curse, and detest those opinions.

-He was sentenced to formal imprisonment at the pleasure of the Inquisition. On the following day this was commuted to house arrest, which he remained under for the rest of his life.

-His offending Dialogue was banned; and in an action not announced at the trial, publication of any of his works was forbidden, including any he might write in the future.

According to popular legend, after his abjuration Galileo allegedly muttered the rebellious phrase Eppur si muove (and yet it moves), but there is no evidence that he actually said this or anything similar.

After a period with the friendly Archbishop Piccolomini in Siena, Galileo was allowed to return to his villa at Arcetri near Florence, where he spent the rest of his life, until his death in 1642, under house arrest. He continued his work on mechanics, and in 1638 he published a scientific book in Holland.

Download Dialogue Concerning the Two Chief World Systems-G.Galilei

The sun, with all those planets revolving around it 

and dependent on it, can still ripen a bunch of grapes 

as if it had nothing else in the universe to do.

Galileo Galilei