Story: Astronomy – overview

Captain Cook with sextant

Captain Cook with sextant

This stamp, issued in 1997 by the New Zealand Post Office to celebrate the navigational work of Captain James Cook, depicts his map of New Zealand and his sextant. Sextants were used to determine a ship’s latitude. They work by measuring the angle between two objects. The observer sights along a half-silvered mirror at the horizon and manipulates a second mirror until an image of the sun, moon, or a star is directed onto the half-silvered mirror and overlays the horizon, then the angle between the horizon and the celestial object is read off the scale.

On 9 November 1769 James Cook and Charles Green determined the latitude and longitude of Mercury Bay during their observation of the transit of Mercury.

Using this item

New Zealand Post
Reference: 1997 Discoverers of New Zealand stamp issue

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How to cite this page:

Maggy Wassilieff, 'Astronomy – overview - The first astronomers', Te Ara - the Encyclopedia of New Zealand, http://www.TeAra.govt.nz/en/photograph/7988/captain-cook-with-sextant (accessed 22 July 2019)

Story by Maggy Wassilieff, published 12 Jun 2006