Ptolemy, copernicus, Galileo

Ptolemy  believed that the Universe was arranged rather like layers of an onion, with the Earth at the centre and the stars at the outermost layer.  Ptolemaic - geocentric

 Copernicus suggested that the Earth was not the centre of the Universe. Instead, he suggested that the Sun was at the centre of a solar system, with the Earth and other planets in orbit around it. Copernaic - heliocentric

Galileo used telescope observations to support Copernicus’ theory.  He observed Jupiter's moon orbitting Jupiter suggesting that not everything orbits the earth and supporting Copernicus theory.  He used a telescope to observe light on Venus suggesting in moves in front of and behind the sun as the Copernican model predicted.

astronomers do not just have telescopes that detect visible light. They have telescopes sensitive to other parts of the electromagnetic spectrum, such as gamma rays, radio waves and X-rays