Reflecting Telescope Inventor: Isaac Newton

The question asks to identify the person credited with inventing the reflecting telescope. This type of telescope uses mirrors to reflect light and form an image, unlike refracting telescopes which use lenses.

Isaac Newton's Contribution to Reflecting Telescopes

Isaac Newton is widely credited with inventing the first practical reflecting telescope. Around 1668, he built his own reflecting telescope design. Key features of his design included:

• Using a parabolic mirror as the primary mirror to focus light.
• Employing a flat secondary mirror, tilted at a 45-degree angle, to direct the focused light to the side of the telescope tube.
• Placing the eyepiece on the side, avoiding the obstruction caused by the objective lens in refracting telescopes.

Newton's primary motivation was to overcome the problem of chromatic aberration (color fringing) that plagued refracting telescopes of his time. His use of a mirror instead of a lens eliminated this issue, leading to clearer images.

Other Astronomers and Their Contributions

While the other options were significant figures in astronomy, they are not credited with inventing the reflecting telescope:

• Johannes Kepler: Improved the design of the refracting telescope, proposing a model with two convex lenses, which increased the field of view, though it still suffered from chromatic aberration.
• Christiaan Huygens: Made significant contributions to optics and astronomy, including improving refracting telescopes and inventing the Huygenian eyepiece. He did not invent the reflecting telescope.
• Galileo Galilei: Significantly improved the refracting telescope design and was the first to systematically use it for astronomical observations, discovering Jupiter's moons and Venus's phases. However, he used refracting telescopes, not reflecting ones.

Therefore, based on historical records and the development of optical instruments, Isaac Newton is the recognized inventor of the practical reflecting telescope.