Britannica
Sources used in this answer
What was William Herschel’s 40-foot telescope like?
Created from Britannica articles
using AI.
AI can make mistakes, so verify using Britannica articles.
William Herschel
Sir William Herschel, detail of an oil painting by L. Abbott, 1785; in the National Portrait Gallery, London.
Sir William Herschel’s 40-foot telescope was a reflecting telescope constructed with the financial support of the King of England. The instrument featured a 120-cm (approximately 4-foot) mirror and a focal length of 12 metres (39 feet), which is often referred to as his 40-foot telescope.1
Herschel utilized this powerful instrument to conduct pioneering astronomical observations, specifically laying the groundwork for the study of extragalactic "nebulas," which are now understood to be galaxies located outside of our own Milky Way system.1