Italian astronomer and mathematician Galileo Galilei built his first telescope in 1609. Using it he saw craters and mountains on the Moon.
Galileo is best known for gathering evidence that supported the Copernican theory that the Earth revolved around the Sun. At the time, Galileo's discoveries were controversial because they challenged the Catholic Church's beliefs and resulted in him being put on trial and imprisoned.
Photo: Illustration showing Galileo in 1638 (Mary Evans Picture Library)
The Italian astronomer challenges orthodox views.
Patrick Moore talks about early Moon observer Galileo.
Sir Patrick Moore and his guest Dr Allan Chapman from Oxford University marvel at how accurate Galileo's maps of the Moon were given that he was using only the most basic of telescopes.
The Italian astronomer's findings challenge orthodox views.
Galileo observes the surface of the Moon for the first time and describes an uneven, imperfect heavenly body.
Dr Allan Chapman explains the instrument's development.
Sir Patrick Moore's guest Dr Allan Chapman explains the telescope's development and importance.
The 17th century scientist sees blemishes on the Sun.
The Italian physicist and mathematician Galileo Galilei was the first person to observe the Sun through a telescope. He saw sunspots moving across the Sun's surface and realised that it was rotating.
Galileo Galilei (Italian pronunciation: [ɡaliˈlɛːo ɡaliˈlɛi]; 15 February 1564 – 8 January 1642), was an Italian astronomer, physicist, engineer, philosopher, and mathematician who played a major role in the scientific revolution during the Renaissance. He is widely heralded as one of the greatest scientists of all time. His achievements include improvements to the telescope and consequent astronomical observations and support for Copernicanism. Galileo has been called the "father of modern observational astronomy", the "father of modern physics", the "father of science", and "the father of modern science".
His contributions to observational astronomy include the telescopic confirmation of the phases of Venus, the discovery of the four largest satellites of Jupiter (named the Galilean moons in his honour), and the observation and analysis of sunspots. Galileo also worked in applied science and technology, inventing an improved military compass and other instruments.
Galileo's advocacy of heliocentrism was controversial within his lifetime, when most philosophers and astronomers still subscribed to the view that the Earth stood motionless at the centre of the universe. After 1610, when he began publicly supporting the heliocentric view, which placed the Sun at the centre of the universe, he was opposed by astronomers, philosophers and clerics. One of the latter, Niccolò Lorini, eventually lodged an informal complaint against Galileo with the prefect of the Congregation of the Index, and another, Tommaso Caccini, formally denounced him to the Roman Inquisition, early in 1615. The subsequent investigation led to the Catholic Church's condemning heliocentrism as "false" and "altogether contrary to the Holy Scripture" in a decree by the Congregation of the Index in February 1616. Although Galileo was not then judged to have committed any offence, he was nevertheless warned to abandon his support for heliocentrism—which he promised to do. When he later defended his views in his most famous work, Dialogue Concerning the Two Chief World Systems, published in 1632, he was tried by the Inquisition, found "vehemently suspect of heresy", forced to abjure, and spent the remaining nine years of his life under house arrest. It was during this period that he wrote one of his finest works, Two New Sciences, in which he summarised the work he had done some forty years earlier, on the two sciences now called kinematics and strength of materials.