MOVING THE SOUTH POLE
A. S. Whitt
Dec. 26, 1993,
Well, it's Boxing Day here at South Pole Station. It's also Sunday so
the ASA staff has the day off, and we're fending for ourselves on the
The weather has been utterly beautiful. Yesterday was -25 F but still
not bad for short walks. Today there's some breeze, and it's amazing how
much colder that makes it feel!
At 2:00 this afternoon the official South Pole was placed in its carefully
Cathleen McDermott and Dale Benson of the USGS (United States Geological
Service) brought the pole with them on the plane trip to the Pole. The
geographical marker on the pole moves about 9.91 meters per year with
the flowing ice. They used two methods to find the new spot.
One is called the Shadow Tip Method. If you stand where the pole is
and look, you can see the straight line of poles stretching off toward
the distance. The Shadow Tip method involves putting a tripod on top of
the old marker and sticking an eight foot rod vertically on the tripod.
Of course all directions at the South Pole are technically "north".
For that reason we have to define another type of north, called "grid
north," which points along the longitude line called the Prime Meridian.
If you were to follow this line of longitude north eventually you would
reach Greenwich, England. Other directions at the South Pole are then
defined with respect to grid north and are expressed as angles of azimuth.
Zero degrees azimuth is in the direction of grid north. Other azimuths
angles are then described as west(turning to the left) or east(turning
to the right) of grid north. For example, if you faced exactly grid north
and then put your left hand straight out to your side it would be pointing
to ninety degrees west azimuth.
When the sun gets to azimuth 40 degrees west of grid north, it is lined
up with the other markers, and the tip of the shadow of the eight foot
pole marks where the new pole should go. (The first of these pole markers
was places with the sun at that azimuth.) And an eight foot rod is used
on top of a six foot tripod, because together they cast a shadow that
is the right length for the rate that the ice is moving each year. At
this time of the year the Sun is near its maximum elevation of 23.5 degrees.
This method is approximate, but is an easy way to find where the pole
should be based upon what we know about the direction and rate of the
flow of the ice.
The other method used the Global Positioning system (GPS). A satellite
network was used to determine the exact spot where 90 degrees south latitude
is on planet Earth. The GPS reading is a few inches off from the shadow-tip
reading, so that there is an official South Pole at the shadow tip and
a little pipe at the GPS spot.
The South Pole marker is about twelve feet long, but about two-thirds
gets pounded into the ground (ice). There were about 30 - 35 people out
in the blowing snow (the sky clouded over at about 10:30 this morning,
the temperature was -9 F, wind chill -46 F: colder than yesterday!)
Dale explained how the position of the pole was determined. He said
that it has been 350 days since the last pole was placed (Jan. 8 of this
year). Cathy put the pole on the spot and Dave Fischer got to take the
first whack at pounding it in, with the special neon orange mallet.
Then each of us got to take a turn pounding it in. Tom Devine (sled
pilot extraordinaire and electrical technician) took my picture, since
I had forgotten the camera, and don't know how accurate it is anyway.
The pole has a decorative plaque on top, which was protected from our
pounding by some bubble wrap and a small block of wood held on with rubber
After everyone had had their picture taken pounding on the pole, somebody
finished pounding it in the rest of the way, and the protective wood was
removed. The plaque has a little dome on it that looks like the station
dome. When I have time, and the wind dies down, I will go look more carefully
at the others.
It was lots of fun, but the wind was so cold we went back in for hot
chocolate right away. And the REAL POLE is set for another year.