Where on Earth are We?
Using the Sky for Mapping the Nordic Countries 1500 – 2000

Martin Ekman

Summer Institute for Historical Geophysics, Åland Islands, 2011
ISBN 978-952-92-9137-3
Hard cover, 138 pages, 17 tables, 25 figures

Description of the book (from its back cover)

This is a book about 500 years of Nordic answers to a very specific question: Where on Earth are we? The theme of the book may be described as: How to use the sky – sun, stars, moons, satellites etc. – to find positions on the Earth in order to construct a map. What we study here is the fundamental positioning for the mapping of the Nordic countries from the 1500s up till today. This is of a wider international interest than might be assumed.

Moreover, the book has a combined scientific and historical perspective throughout. On one hand, science is used to contribute to understanding the historical development of positioning and mapping. On the other hand, the historical development is used to contribute to understanding the principles behind modern scientific positioning. Original scientific sources (and maps) are used throughout. This means throwing light also on important works no longer known to modern scientists.

Finally, in order to broaden the outlook in somewhat unexpected directions, some special aspects related to the positioning and mapping problems are included at the end of the book.

This book spans from astronomy via geodesy to mapping (and partly navigation). It is intended for reading by a wide range of geoscientists or other people with a professional interest in the mapping of the Earth.

Table of contents


  1. Introduction: Combining the sky and the Earth
    1.1 How does one make a map?
    1.2 Northern positioning with international connections
    1.3 Coordinates on the Earth and in the sky
  2. Sun and latitude: General maps of the first generation
    2.1 The sun at the Arctic circle
    2.2 The first maps based on sun observations
  3. Stars and latitude: General maps of the second generation
    3.1 The observatory on the island: The stars at Uranienborg
    3.2 The first maps based on star observations
    3.3 The moving pole in the sky
    3.4 New observatories at Paris and Greenwich
  4. Moons and longitude: General maps of the third generation
    4.1 The Jupiter moons at Uppsala
    4.2 The first maps based also on moon observations
    4.3 Connections to Paris and Greenwich
  5. Stars, clocks and triangles along coasts: Marine charts
    5.1 Solving an international controversy: The arc at the Arctic circle
    5.2 The triangles across the Baltic Sea
    5.3 Triangulation along the coasts and the first nautical charts
    5.4 Shipping clocks across the North and Baltic Seas
  6. Stars and triangles on continents: Topographic maps
    6.1 The Earth as an ellipsoid of revolution
    6.2 Triangulation inland and the first topographic maps
    6.3 Continental triangulations and maps
  7. Stars and satellites: Mapping in a global system
    7.1 Star observations and hidden masses inside the Earth
    7.2 How to connect continents?
    7.3 Distant galaxies and close satellites
    7.4 The moving pole on the Earth – and the moving continents
    7.5 A brief review
  8. Some special aspects
    8.1 Modern coordinates of old fundamental observatories
    8.2 A triangulation lost and retrieved
    8.3 Ships instead of satellites
    8.4 Making maps with needles

References (in chronological order)