I have often heard that from the north or south pole every direction on a compass points either north or south respectively, which leaves me wondering how polar explorers navigate and what equipment do they use. Do they rely on GPS or have some sort of special compass or equipment. How do they know which is the ''right'' direction, presumably allowing for magnetic variation in usual sense when in the british hills would be totally useless. Also old-time polar explorers like scott and shackleton etc would obviously not have had modrn technology so what method did they use to navigate.
Navigating in Polar Regions
- Thread starter Joonsy
- Start date
The magnetic compass needle not only points south (or north) no matter what direction you face (assuming it will point at all) but every direction IS south or north from the opposite poles.
Now-a-days polar navigation is done by GPS or other electronic means. I've also often wondered how the explorers did so pre the modern age. Stellar nav perhaps?
Now-a-days polar navigation is done by GPS or other electronic means. I've also often wondered how the explorers did so pre the modern age. Stellar nav perhaps?
Most texts I have come across refer to using the suns position and a good chronometer.
This could vary between using a sextant to a simple wooden "bearing dial" type device that I saw in one book. (I'm still investigating that one.)
This could vary between using a sextant to a simple wooden "bearing dial" type device that I saw in one book. (I'm still investigating that one.)
At the magnetic poles, the magnetic compass does not point south or north, it points down! At the magnetic poles, the direction of the magnetic flux is perpendicular to the surface of the earth. However, as the magnetic poles and the geographic poles are not in the same place, this is only a problem at the magnetic poles.
When navigating in polar regions, astronomical methods work well, and a system called "Isogriv" mavigation can be used as well. Isogriv navigation relies on the angle of magmetic variation between the users posititon, the magnetic pole and the destination. Used by someone who is skilled in the method, it is quite accurate, but in inexperienced hands it is easy to make enormous errors.
Some years ago, an aircraft was shot down over Central Siberia following a trans-polar flight which supposed to be going to Tokyo. The enquiry concluded that the navigator, who had never used the Isogriv system before, had made an error of almost 90 degrees, and at the time of the interception was nearly 1200 miles off course.
Marine and aircraft compasses are designed to function over about 98% of the earth's surface, and only become inaccurate within a few miles of the magnetic poles.
Due to the influence of electro-magnetic phenomena in the upper atmosphere, GPS is unreliable in high latitudes, and ground-based radio navigation systems can also be badly affected. Rather than a conventional sextant, which requires a level horizon, the bubble sextant or the theodolite are used for astro navigation.
Modern navigation aids like gyro cmpasses and inertial navigation systems make polar navigation easier, and some radio navigation systems can be used, as long as the navigator is aware of, and takes account of,the limitations of the system in use.
I hope this information is helpful.
Alan.
When navigating in polar regions, astronomical methods work well, and a system called "Isogriv" mavigation can be used as well. Isogriv navigation relies on the angle of magmetic variation between the users posititon, the magnetic pole and the destination. Used by someone who is skilled in the method, it is quite accurate, but in inexperienced hands it is easy to make enormous errors.
Some years ago, an aircraft was shot down over Central Siberia following a trans-polar flight which supposed to be going to Tokyo. The enquiry concluded that the navigator, who had never used the Isogriv system before, had made an error of almost 90 degrees, and at the time of the interception was nearly 1200 miles off course.
Marine and aircraft compasses are designed to function over about 98% of the earth's surface, and only become inaccurate within a few miles of the magnetic poles.
Due to the influence of electro-magnetic phenomena in the upper atmosphere, GPS is unreliable in high latitudes, and ground-based radio navigation systems can also be badly affected. Rather than a conventional sextant, which requires a level horizon, the bubble sextant or the theodolite are used for astro navigation.
Modern navigation aids like gyro cmpasses and inertial navigation systems make polar navigation easier, and some radio navigation systems can be used, as long as the navigator is aware of, and takes account of,the limitations of the system in use.
I hope this information is helpful.
Alan.
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I remember when that happened, it was more than "a few years ago" though; it was in the early 80s; I was still stationed in Bergstom AFB, Texas. By that time airliners had been using electronic nav (although not GPS yet) for decades though, so it's unlikely he was relying on a magnetic compass. The standard aviation nav systems at that time would have been INS, earlier sat navs, and/or radio beacon nav.
Yes those systems have some limitations too, as you pointed out. But they're generally reliable if cross referenced against each other.
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Thankyou Wayland for adding that. After googling i have learned that both sextant and theodolite were used by Amundsen and Scott as told in this link http://answers.yahoo.com/question/index?qid=20090921065737AApFBeH though it explains how they found the pole not how they found their way ''back'' from the pole but similar tactics i imagine
Thankyou Ratcatcher for adding that reply, it is indeed both helpful and interesting.
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