Greenwich 28-inch refractor

The Greenwich 28-inch refractor is a long-focus telescope housed within a distinctive onion-domed structure at the Royal Observatory. The instrument combines a 19th-century mounting design with a later optical tube configuration.

The mounting system originated in the 1850s through a design by Royal Observatory director George Airy and the engineering firm Ransomes and Simms. The optical tube was added later, with the complete instrument becoming operational in 1893.

The telescope contributed to astronomical research with over 1300 observations of double stars conducted between 1960 and 1963 at the Royal Observatory.

Visitors need to climb through several levels to see the complete structure and function of the telescope. Comfortable shoes are helpful, and joining a guided tour provides better understanding of how the instrument works.

During World War II, the objective lens was removed and stored separately to protect it from bomb damage during air raids. This action reflects how valuable the instrument was considered to the scientific community at the time.

Location: Royal Borough of Greenwich

Operator: Greenwich Royal Observatory

Website: https://rmg.co.uk/royal-observatory/flamsteed-house-and-meridian/28-inch-telescope

GPS coordinates: 51.47774,-0.00114

Latest update: December 12, 2025 12:05