Saturday, 19 November 2016

The South Pole(s)

Is it true there is more than one South Pole?
How do you know when you've got to the South Pole?

Two good questions!

There are actually four South Poles (and some of them don’t even stay in the same place). They are the Geographic South Pole, the Magnetic South Pole, the Geomagnetic South Pole and – my favourite – the South Pole of Inaccessibility.

The Geographic South Pole
This lies at a latitude of 90 degrees south. It is the southernmost point of the earth, so whichever direction you look, you will be looking north. This South Pole was the goal that all the early explorers were trying to reach, and where Edmund Hillary headed on his Ferguson tractor in December 1957. Today there is an American station there, called the US Amundsen-Scott South Pole Station, and if you are very lucky, you can fly there.  

The Magnetic South Pole
The position of the Magnetic South Pole changes over time, as you can see from this map – in fact it now lies in the Southern Ocean, over 2800 km from the Geographic South Pole.
If you use a compass in the southern hemisphere, the needle points south to the Magnetic South Pole, which means a compass is no good for finding your way to the Geographic South Pole.
Lots more good info about magnets here, including what would a compass do at the Magnetic South Pole, and a suggested answer to the question about how you would know you've got to the South Pole, and especially how the early explorers knew, if they couldn't rely on compasses (keep scrolling down for that one - a clue - it's to do with the sun.)  

The Geomagnetic South Pole
I’m not even going to try and explain what this one is but here’s one of the best explanations I’ve found for the differences between those three Poles.
The South Pole of Inaccessibility
This is the very centre of Antarctica, if you define “the centre” as being the part furthest away from the sea. But there are different opinions as to exactly where that is, because it depends on where you say the coastlines are, when some are buried under ice sheets. (There is also a North Pole of Inaccessibility in the Arctic, and Poles of Inaccessibility in the other continents - you can read about them here.)
Another site suggests there are three more South Poles (making seven altogether): the South Pole of Rotation, the South Celestial Pole and the South Pole of Cold. You can find out more here.

South Pole; Photo by Josie McNee
©Antarctica New Zealand Pictorial Collection [1989-1990] CC licence

No comments:

Post a Comment