Appreciating People Human environments: People living and working in the local area; People living and working in a contrasting part of Ireland

Copernicus’s explanation for this was that the planets revolved around the sun rather than around the Earth. His ideas went against the teachings of the Catholic Church, which said that the Earth was at the centre of the universe. Going against the Church frightened Copernicus so much that his book was published only after his death. When news of his theories reached the Vatican (the headquarters of the Catholic Church in Rome), his ideas were condemned. However, his theories spread because copies of his book continued to be printed.

Galileo Galilei (1564–1642)

When Copernicus’s theories reached Florence, Italy, they fascinated the astronomer Galileo Galilei. The telescope had recently been invented. Galileo made improvements that allowed the telescope to magnify objects to eight or nine times their size. He used his new telescope to make important discoveries. He studied the planet Jupiter and discovered four of its moons: Io, Europa, Ganymede and Callisto. When he studied the Earth’s moon, he saw that its surface was covered in craters and mountains, which cast shadows that changed according to the position of the sun. He used the length of the shadows to calculate the height of the mountains. Galileo discovered that the Milky Way was made up of thousands of individual stars. He also discovered that Venus had phases, just like the moon. This confirmed Copernicus’s theory that Venus (and the other planets) revolved around the sun rather than the Earth. Galileo’s use of observation and experimentation formed the basis of the scientific method that we still use today. However, when he published his discoveries, the Catholic Church banned his books and put him on trial for arguing against its teachings. He was found guilty, but fortunately he had powerful friends who saved him from being executed. Galileo spent the rest of his life under house arrest. He continued to work on his theories at home until his death. As telescopes became more powerful, evidence to support heliocentrism became widely accepted. In 1885, Copernicus and Galileo’s writings were taken off the Catholic Church’s list of banned books.

The Vatican Surface of the moon Galileo Galilei ©The Educational Company of Ireland Trial of Galileo