Thecelatone was a device invented byGalileo Galilei to observeJupiter's moons with the purpose of findinglongitude on Earth. It took the form of a piece of headgear with atelescope taking the place of an eyehole.

In 2013, Matthew Dockrey created a replica celatone, using notes from a version created by Samuel Parlour. From April 2014 to January 2015, Dockrey's celatone was on display in theRoyal Observatory, Greenwich in east London.

• Longitude prize
• Galilean moons

• Sobel, Dava (1995).Longitude: The True Story of a Lone Genius Who Solved the Greatest Scientific Problem of His Time. Penguin.ISBN 0-14-025879-5.

• Video animation of a Celatone and its use in discovering the longitude for marine navigation
• Dockrey celatone
• "Apparatus to render a telescope manageable on shipboard"

• Astronomical instruments

• Articles with short description
• Short description matches Wikidata