Astro Facts  

Nicolaus Copernicus (1437-1543) advocated the Heliocentric Theory (a theory that Earth moves around the Sun) in opposition to the Geocentric Theory (a theory that Earth is the center of the Universe). Galileo Galilei (1564-1642) used a handmade telescope to research planets, supporting the Heliocentric Theory. Johannes Kepler (1571-1630) studied the orbit of planets and also believed that the Heliocentric Theory is accurate at the same time as Galileo. Kepler invented the Keplerian telescope, another type of refracting telescope of the Galilean telescope. Since the eyepiece of the Keplerian telescope uses a convex lens, the image seen through the telescope looks upside down. However, it allows us a wider field of view and higher magnification, so many astronomers preferred the Keplerian telescope.