# Monthly Archives: January 2012

## Titanic and the Traverse Tables

Recent discussions regarding the possibility that the SOS position sent by the Titanic was incorrect due to mistakes made in applying the traverse tables make interesting reading. Traverse tables have been used for about 200 years to solve the mathematical … Continue reading

## Planning Star and Planet Observations

I have been asked about using ABC tables to calculate azimuth and altitude when planning star and planet observations.  Unlike the Sun and the Moon which are easily identified, the approximate positions of stars and planets need to be established … Continue reading

## Astro Navigation In A Survival Situation

In a recent survey, the majority of people questioned were surprised to learn that astro navigation can be used in a survival situation.  In the same survey, 60% said that they would use satellite navigation systems to find their way … Continue reading

## Finding Latititude In A Survival Situation.

The  full method of calculating your latitude from the altitude of the Sun can be found at this link.  However, in a survival situation, the following simplified method can be used. Equipment Needed.  A clinometer or other device for measuring angles. … Continue reading

## Astro Navigation – What is it and why do we need it?

Astro-navigation (or celestial navigation as it is also known) is a fascinating subject that encompasses many areas of knowledge including geography, astronomy, history and mathematics.  As you unravel the principles and techniques upon which navigation is based, you will be … Continue reading

## Finding Longitude In A Survival Situation.

We know that the Earth revolves about its axis once every 24 hours.  In other words, the Sun completes its apparent revolution of 360o in 24 hours.  This means that the Sun crosses each of the 360 meridians of longitude once … Continue reading

## Latitude from Polaris

Using The Pole Star (Polaris)  To Find Your Latitude Assume that the Pole Star (Polaris)is exactly in line with the Earth’s axis produced, as shown in the following diagram. To an observer O on the Equator (lat. 0o) the Pole … Continue reading

## Spherical Trigonometry Introduction

In the diagram above, the inner circle represents the Earth and the outer circle represents the celestial sphere.  Point N represents the North Pole, B represents an observer’s position on the surface of the Earth, and U represents the geographical … Continue reading

## Distance to the Horizon

The Pharos Lighthouse.  The Pharos Lighthouse or the Lighthouse of Alexandria as it was also known, was commissioned by Ptolemy Soter the ruler of Egypt and completed during the reign of his son Ptolemy II in about 270BC.  It was … Continue reading

## Revise Pythagoras’ Theorem

If after reading some of my other posts, you feel you are a bit rusty on Pythagoras’ Theorem, here is a quick brush up for you.  We can see in the diagram below that, in the triangle ABC, if a … Continue reading