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Galileo, 1564–1642, great Italian astronomer, mathematician, and physicist. By his persistent investigation of natural laws he laid foundations for modern experimental science, and by the construction of astronomical telescopes he greatly enlarged humanity's vision and conception of the universe. He gave a mathematical formulation to many physical laws.

Galileo Galilei was born on February 15, 1564, in Pisa in the Duchy of Florence, Italy. He was the first of six children born to Vincenzo Galilei, a well-known musician and music theorist, and Giulia Ammannati. In 1574, the family moved to Florence, where Galileo started his formal education at the Camaldolese monastery in Vallombrosa.In 1583, Galileo entered the University of Pisa to study medicine. Armed with high intelligence and talent, he soon became fascinated with many subjects, particularly mathematics and physics. While at Pisa, Galileo was exposed to the Aristotelian view of the world, then the leading scientific authority and the only one sanctioned by the Roman Catholic Church. At first, Galileo supported this view, like any other intellectual of his time, and was on track to be a university professor. However, due to financial difficulties, Galileo left the university in 1585 before earning his degree.

GALILEOGALILEIELDER

DAUGHTER

Galileo continued to study mathematics, supporting himself with minor teaching positions. During this time he began his two-decade study on objects in motion and published The Little Balance, describing the hydrostatic principles of weighing small quantities, which brought him some fame. This gained him a teaching post at the University of Pisa, in 1589. There Galileo conducted his fabled experiments with falling objects and produced his manuscript Du Motu (On Motion), a departure from Aristotelian views about motion and falling objects. Galileo developed an arrogance about his work, and his strident criticisms of Aristotle left him isolated among his colleagues. In 1592, his contract with the University of Pisa was not renewed.

Galileo quickly found a new position at the University of Padua, teaching geometry, mechanics and astronomy. The appointment was fortunate, for his father had died in 1591, leaving Galileo entrusted with the care of his younger brother Michelagnolo. During his 18-year tenure at Padua, he gave entertaining lectures and attracted large crowds of followers, further increasing his fame and his sense of mission.

HELIOCENTRICMODEL OF THESOLAR SYSTEM

One of Galileo's most famous "inventions" was his confirmation that the sun is the center of our solar system, a theory first put forward by Nicolaus Copernicus. Galileo confirmed the theory partly through his observation of the phases of the planet Venus as it reflected light from the sun while orbiting the star. This was revolutionary at the time because most of the world still believed Earth was the center of the universe. The Catholic Church arrested Galileo as a heretic for this.

Although the telescope was invented in 1608 by Dutchman Hans Lippershey, Galileo built his own in 1609, without ever having seen Lippershey's, and he improved it over time from 3X magnification to about 30X. He built his first telescope based on descriptions he had heard. He was the first to use a telescope to observe the heavens.

THE PENDULUM

While watching a chandelier swing back and forth at the Cathedral of Pisa in 1583, Galileo noticed something curious. We might expect a chandelier swinging farther to take longer, but not so. Galileo noticed that the time period to swing through one complete cycle is independent of the amplitude through which it swings. One can duplicate Galileo's pendulum experiments by timing a weight swinging on the end of a string. For not too large amplitudes, the time period for one complete cycle will be the same regardless of amplitude. The period does however depend on the length of the string. A longer pendulum will take longer to complete one cycle. For these experiments we would use a stopwatch, perhaps one built into most digital watches these days. But in Galileo's time, wristwatches were not yet available. He timed the swings with his pulse, the only timing device at hand.

Galileo was one of the first Europeans to observe sunspots, although Kepler had unwittingly observed one in 1607, but mistook it for a transit of Mercury. He also reinterpreted a sunspot observation from the time of Charlemagne, which formerly had been attributed (impossibly) to a transit of Mercury. The very existence of sunspots showed another difficulty with the unchanging perfection of the heavens as posited in orthodox Aristotelian celestial physics. And the annual variations in sunspots' motions, discovered by Franesco Sizzi and others in 1612–1613, provided a powerful argument against both the Ptolemaic system and the geoheliocentric system of Tycho Brahe. A dispute over priority in the discovery of sunspots, and in their interpretation, led Galileo to a long and bitter feud with the Jesuit Christoph Scheiner; in fact, there is little doubt that both of them were beaten by David Fabricius and his son Johannes. Scheiner quickly adopted Kepler's 1615 proposal of the modern telescope design, which gave larger magnification at the cost of inverted images; Galileo apparently never changed to Kepler's design.

GALILEANMOONS

The Galilean moons are the four moons of Jupiter discovered by Galileo Galilei around January 1610. They are by far the largest of the moons of Jupiter and derive their names from the lovers of Zeus: Io, Europa, Ganymede, and Callisto. They are among the most massive objects in the Solar System outside the Sun and the eight planets, with radii larger than any of thedwarf planets. The three inner moons – Ganymede, Europa, and Io – participate in a 1:2:4 orbital resonance.

Io

Europa

Ganymede

Callisto

Galileo,Kepler and TheTheories of Tides

Cardinal Bellarmine had written in 1615 that the Copernican system could not be defended without "a true physical demonstration that the sun does not circle the earth but the earth circles the sun". Galileo considered his theory of the tides to provide the required physical proof of the motion of the earth. This theory was so important to him that he originally intended to entitle his Dialogue on the Two Chief World Systems the Dialogue on the Ebb and Flow of the Sea. The reference to tides was removed by order of the Inquisition.

For Galileo, the tides were caused by the sloshing back and forth of water in the seas as a point on the Earth's surface sped up and slowed down because of the Earth's rotation on its axis and revolution around the Sun. He circulated his first account of the tides in 1616, addressed to Cardinal Orsini. His theory gave the first insight into the importance of the shapes of ocean basins in the size and timing of tides; he correctly accounted, for instance, for the negligible tides halfway along the Adriatic Sea compared to those at the ends. As a general account of the cause of tides, however, his theory was a failure.

If this theory were correct, there would be only one high tide per day. Galileo and his contemporaries were aware of this inadequacy because there are two daily high tides at Venice instead of one, about twelve hours apart. Galileo dismissed this anomaly as the result of several secondary causes, including the shape of the sea, its depth, and other factors. Against the assertion that Galileo was deceptive in making these arguments, Albert Einstein expressed the opinion that Galileo developed his "fascinating arguments" and accepted them uncritically out of a desire for physical proof of the motion of the Earth. Galileo dismissed the idea, held by his contemporary Johannes Kepler, that the moon caused the tides.He also refused to accept Kepler's elliptical orbits of the planets, considering the circle the "perfect" shape for planetary orbits

Galileo Achievements

In 1609 Galileo Galilei made a telescope by using two Lenses on the sides of the pipe made of lead. It was better than the telescope of Lebrshy. After that he improved his telescope and He sold many of his inventions in many European countries. He became very famous, especially in Venice.

It was believed that the earth is the center of the universe and the stars and the sun turning around it, And the Milky Way is a light found in the sky, With his telescope he discovered that is wrong.

He found that there were heights on the moon and Jupiter has moons like the our moon which found around the earth.

He found that the Milky Way is a cloud consist on a big number of nebula and separated stars.

He Was the first to introduce inertia science and fall objects and put the modern laws for it and he was the first man looked at the sky with telescope and he discovered a large number of stars.

He was the first man who discover sunspots, but as a result of that Galileo faced large objection from the church when he said that the earth revolves around the sun, he was right, but the church ordered  to kill him, but with the development of science emerged the fact that he was right in what he said.

Galileo studied several other sciences, such as mathematics and medicine as his father taught him to play the lute and poets as it was a masterful painter but opposed a lot of the theories of Aristotle, which was important for scientists at the time.

The invention of the telescope is very important for people at the time and used by sailors in seeing distant ships as he discovered that there are many stars in the galaxy has scored 4 moons orbiting Jupiter, as well as rings of Saturn Church objected to all this and looked at the planets it is driven by the angels and the sun is orbiting the earth.Church imprisoned Galileo and hanged after that, but after several years science triumphed over the Church and proved the validity of his theories.

Books on Galileo Galilei

DEATH OF GALILEOGalileo 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. These plans were scrapped, however, after Pope Urban VIII and his nephew, Cardinal Francesco Barberini, protested, because Galileo was condemned by the Catholic Church for "vehement suspicion of heresy". He was instead buried in a small room next to the novices' chapel at the end of a corridor from the southern transept of the basilica to the sacristy. He was reburied in the main body of the basilica in 1737 after a monument had been erected there in his honour; during this move, three fingers and a tooth were removed from his remains.One of these fingers, the middle finger from Galileo's right hand, is currently on exhibition at the Museo Galileo in Florence, Italy.