Calculating Changes in Longitude and Time Along a Parallel of Latitude.

If two ships are both positioned exactly on the Equator but are separated by 900 nautical miles in an east/west direction, then in terms of longitude, they will be 15o apart and in terms of Greenwich Mean Time, they will be … Continue reading

The Importance of Azimuth and Altitude in Astro Navigation

In the diagram above, the celestial sphere is drawn in the plane of the observer’s meridian with the observer’s zenith (Z) at the top.  Point O represents both the observer and the Earth. Z represents the observer’s zenith. X is … Continue reading

Bearing, Azimuth and Azimuth Angle.

For students of astro navigation, the various definitions of azimuth, azimuth angle and bearing can cause much confusion. It is hoped that the following will help to clarify this topic. Bearing is the direction of something in relation to a … Continue reading

A Plan Of Mathematical Perfection. (Learning from the Polynesians)

In the two previous posts of this series, we focussed on astro navigation aspects of the ancient voyaging techniques of the Polynesians and the Micronesians.  Because of that narrow focus, we did not do justice to the abounding knowledge and … Continue reading

Pillars of the Sky (Learning from the Polynesians).

The last post in this series discussed the Polynesian’s Star Compass and their use of ‘steering stars’ for direction finding.  Although the Polynesians made extensive use of a form of dead reckoning to estimate position, as far as we know, … Continue reading

The Polynesian Star Compass (Learning from the Polynesians)

Updated version. “Know the stars and you will always have a compass”  (The Revenant) * Nainoa Thompson tells us how that, for centuries before European sailors reached the Pacific Ocean, the South Sea Islanders accurately found their way from island … Continue reading

Astro Navigation In A Nutshell Part Four

Part 4 – Full procedure for establishing an astronomical position line. This post brings together all of the information from parts 1, 2 and 3 of this series to demonstrate the full procedure for establishing an astronomical position line. .Links:  Astro … Continue reading

Astro Navigation In A Nutshell Part 1

Links Astro Navigation in a Nutshell Part 2 Astro Navigation in a Nutshell Part 3 Astro Navigation in a Nutshell Part 4 Part 1 – The Importance of Azimuth and Altitude.  The theory of astro navigation depends on the ability … Continue reading

Astro Navigation In A Nutshell Part 2.

Part 2 – The Intercept Method Link:  Astro Navigation In A Nutshell Part One Astro Navigation in a Nutshell Part 3 Astro Navigation in a Nutshell Part 4 Suppose we are in a yacht and we measure the altitude of … Continue reading

Astro Navigation in a Nutshell Part 3

Part 3 – Calculating Altitude and Azimuth at the Assumed Position by Spherical Trigonometry. Links:  Astro Navigation In A Nutshell Part One Astro Navigation In A Nutshell Part Two Astro Navigation in a Nutshell Part 3 Astro Navigation in a Nutshell … Continue reading