Astronomer, physicists, and engineer from the italian city-state of pisa. he came up with new and improved designs for the compass and the thermometer. in 1609 he started working to improve the telescope and his improved telescope was 10 times more powerful than previous ones. he used the telescope to study the moon and space and realized that ptolemy was wrong. he published his finding in the 1610 book the starry messenger which showed that he agreed with copernicus which confirmed the heliocentric model. a: galen b: galilei c: andrew vesalius d: ptolemy