Tag Archives: astro navigation

In Defence of Mer Pas

The noon sight for latitude is a method of calculating latitude from the altitude of the sun at the instant it crosses your meridian and for this reason, the method is also known as ‘Meridian Passage’ or ‘Mer. Pas’.  I … Continue reading

Posted in astro navigation, astronomy, celestial navigation, gps, navigation | Tagged , , ,

Celestial Navigation – Theory and Practice

I have received a number of messages asking why my book ‘Celestial Navigation – The Ultimate Course’ is not currently available.  The truth is that I have been spending the winter months revising and updating this book and it will … Continue reading

Posted in astro navigation, astronomy, celestial navigation | Tagged , ,

Why Astro?

In a recent article the discussion centred on our over-reliance on GPS for navigation at sea and the need for back-up systems.  The conclusion drawn was that we already have a back-up system, one that has been tried and tested … Continue reading

Posted in astro navigation, celestial navigation, electronic navigation systems, global positioning system, gps, Marine Navigation, navigation | Tagged , , ,

Astro Navigation in the Forests of the Iroquois

Link: History of the Mason Dixon line Jeremiah Dixon and Charles Mason plotted the famous Mason Dixon Line in 1765, long before the days of GPS or any other electronic navigation equipment. How was it then that they were they able … Continue reading

Posted in astro navigation, astronomy, celestial navigation | Tagged , , ,

Translating A Celestial Position Into A Geographical Position.

This follows the previous post which discussed the Celestial Co-ordinate System. If we wish to use a celestial body’s position in the celestial sphere to help us to navigate on the Earth’s surface, we must be able to translate that … Continue reading

Posted in astro navigation, astronomy, celestial navigation, celestial sphere | Tagged , , , ,

The Celestial Co-ordinate system.

In astronomy, we need a celestial co-ordinate system for fixing the positions of the celestial bodies in the celestial sphere. We express a celestial body’s position in the celestial sphere in relation to its angular distance north or south of … Continue reading

Posted in astro navigation, astronomy, celestial navigation, celestial sphere | Tagged , , ,

What’s The Point of Astro Navigation When We Have The GPS?

Imagine that you are driving through Birmingham when, suddenly, your ‘Sat Nav’ starts to tell you that you are in Manchester.  In such a situation, you would quickly realise that the GPS had gone haywire; however, if you were in … Continue reading

Posted in astro navigation, Astro Navigation Topics, astronomy, celestial navigation, coronal mass ejections, electronic navigation systems, gps | Tagged , , , ,

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

Posted in astro navigation, Astro Navigation Demystified, celestial navigation, navigation | Tagged , , , ,

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

Posted in astro navigation, astronomy, celestial navigation, navigation | Tagged , ,

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

Posted in astro navigation, astronomy, celestial navigation, Marine Navigation, navigation | Tagged , , , , , ,