---
title: "Celatone"
chunk: 1/1
source: "https://en.wikipedia.org/wiki/Celatone"
category: "reference"
tags: "science, encyclopedia"
date_saved: "2026-05-05T09:40:16.196142+00:00"
instance: "kb-cron"
---

The celatone was a device invented by Galileo Galilei to observe Jupiter's moons with the purpose of finding longitude on Earth.  It took the form of a piece of headgear with a telescope taking the place of an eyehole.


== Modern versions ==
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 the Royal Observatory, Greenwich in east London.


== See also ==
Longitude prize
Galilean moons


== References ==

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.


== External links ==
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"