Nicolaus Copernicus was a Polish astronomer. Pictured below is his view of the Universe. He proposed that it was the Sun - not the Earth - which was at the centre of the Universe. The Earth and the other planets simply revolved around it. His idea was proved correct in the 1620s when the Italian Galileo Galilei used an early telescope to observe the planet Jupiter. He could clearly see that there were other moons in orbit round Jupiter. Here were bodies which were not moving round the Earth. This meant one thing: that the Earth was not the centre of the Universe.
Fact file
Galileo's telescopes were more powerful than any that had been used before. He was the first person to study the night sky through a telescope.
resources: Tell me why (CHancellor Press)
image 1: https://dailyasianage.com/library/1518980366_5.jpg
image 2: https://news.nationalgeographic.com/news/2009/08/photogalleries/galileos-telescope-pictures-anniversary/images/primary/090825-01-galileos-telescope_big.jpg