Gregorian telescope

English

Etymology

Designed by Scottish mathematician and astronomer James Gregory in the 17th century.

Noun

Gregorian telescope (plural Gregorian telescopes)

1. A type of reflecting telescope having two concave mirrors: the primary mirror (a paraboloid) collects the light and brings it to a focus before the secondary mirror (a ellipsoid), where it is reflected back through a hole in the centre of the primary, and thence out the bottom end of the instrument, where it can be viewed with the aid of the eyepiece.