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Scale of the object compared with an adult hand.

Curriculum links

About the object

Sailors use sextants to work out their ship’s location at sea so they can navigate. This brass sextant was made in the late nineteenth century.

Sextants were used to measure angular altitudes of celestial bodies whilst at sea, enabling sailors to determine latitude and local time.

Sextants were also used to calculate longitude at sea using the so-called ‘lunar distance’ method, carried out by comparing an accurate measurement of the angular distance between the Moon and a fixed star to a set of pre-calculated tables.

Navigation today

Today satellite navigation tools, such as GPS, are the most common form of navigation for people at sea.

However, many sailors still learn the skills to navigate using time, mathematics, the Moon and the stars to aid their journeys.

Discussion questions

  1. Have you ever been unsure of where you are? If you were lost, what could you do to try and find out where you are?
  2. GPS is an incredible tool that uses satellites to track your location. As such, others can track your signal and know your past and present location. Who would you be alright with knowing your location at all times? Your friends? Your family? The government?

Explore the sextant