Loading...

Glossary term: Galilean Telescope

Description: In a refracting telescope, light first encounters a convex lens, called the objective lens, which serves to bundle infalling parallel light rays. Such almost perfectly parallel light rays correspond to light we receive from a distant object, such as a star. In order to produce an image that can be observed by eye, those converging rays must be made parallel again. In a Galilean telescope, named after the model of telescope built by Galileo Galilei in 1609 and used for some of the first systematic astronomical telescope observations, this is achieved by inserting a convex lens. In contrast, in a Keplerian telescope, invented by Johannes Kepler in 1611, the converging light rays are allowed to cross, and the resulting divergent light rays are then made parallel using a second convex lens.

Related Terms:


See this term in other languages

Term and definition status: This term and its definition is still awaiting approval

The OAE Multilingual Glossary is a project of the IAU Office of Astronomy for Education (OAE) in collaboration with the IAU Office of Astronomy Outreach (OAO). The terms and definitions were chosen, written and reviewed by a collective effort from the OAE, the OAE Centers and Nodes, the OAE National Astronomy Education Coordinators (NAECs) and other volunteers. You can find a full list of credits here. All glossary terms and their definitions are released under a Creative Commons CC BY-4.0 license and should be credited to "IAU OAE".