A: Not all of them did know. And worse, some knew they hadn’t achieved their goal, but lied anyway in their eagerness to be first. But in principle, it was simple: When they reached 90 degrees latitude, as determined from sextant readings, they were there.

"Shooting the Sun at the South Geographical Pole. Amundsen (left) is holding the sextant. Helmer Hanssen (right) is bending over the artificial horizon, which is a tray of mercury. Amundsen is lining up the direct image of the Sun with its reflection in the surface of the mercury," writes Amundsen in his book, The South Pole. Peter Ifland, author of Taking the Stars, suspects that the picture is posed. "It would be impossible to take a sight while standing so far away from the artificial horizon. Normally, one would kneel down and hold the sextant a few inches from the artificial horizon to catch the image of the sun reflected by the mercury pool." Courtesy of the National Oceanic & Atmosphere Administration (NOAA)

The first man to the North Pole and the first man to the South Pole turns out (now that we’ve evaluated all the claims) to be the Norwegian, Roald Amundsen. In 1926, he floated over the North Pole in the Airship Norge — an undisputed sighting. In 1911, he trekked to the South Pole, and actually got within 200 yards (200 m) of his goal.

This is an amazing feat, considering that modern sextants measure to 0.2 minutes of arc, an error that translates to a distance of about 400 yards (400 m). Robert Scott, who arrived about a month later, missed the pole by about 450 yards (450 m).

In 1929, Hubert Paton takes a Sun sight aboard the Lydonia, using a sextant much like Amundsen used in 1911. Courtesy of NOAA.

The early polar explorers used the same simple navigation plan that served seafarers well for centuries.

The system worked well for Amundsen, with one slight modification. Instead of calculating distance from speed and time measurements, he measured distance with odometers screwed to his sledges. Basically, an odometer counts the number of revolutions of a wheel, and, knowing the circumference of its wheel, computes the distance.

"Polar Transport", from Amundsen’s book. Each sledge contained an odometer to measure distance traveled. Courtesy of NOAA.

Amundsen and his ‘brave little band" (Olav Bjaaland, Helmer Hanssen, Sverre Hassel and Oscar Wisting) trekked to the South Pole in three sledges pulled by sled dogs. To find their way through featureless white plains, they followed an order of march: a lead skier (perhaps Hassel), "to show the direction and encourage the dogs". Next came Helmer Hanssen as "our most efficient dog-driver." He carried the most-accurate compass on his sledge and checked the lead skier’s direction. After him came Bjaaland, also with a compass. "Lastly, I came, with sledge-meter and compass..," wrote Amundsen in his epic book, The South Pole.

The lead skier, in this case Hassel, had it rough. "It is no easy matter to go straight on a surface without landmarks," explains Amundsen. "Imagine an immense plain that you have to cross in thick fog; it is dead calm, and the snow lies evenly, without drifts. What would you do? An Eskimo [aka Inuit] can mange it, but none of us. We should turn to the right or to the left, and give the leading dog-driver with the standard compass endless trouble." That’s why Hansen, in the first sledge with the best compass, would correct the forerunner’s direction. "A little to the right," he would shout, and imply (knowing full well he could do no better, but still exasperated), "Duffer!"

"Roald Amundsen", a savvy planner and brilliant explorer, from Amundsen’s book. Courtesy of NOAA.

But these folk were good — their dead reckoning right on the money. They had adjusted their compasses and sledge-meters at their base station, and knew that they could rely on them. But even they were surprised at the accuracy of their dead reckoning.

The present-day South Pole Station on a day without horizons. Amundsen writes of one such day: "A grey haze, the most unpleasant (after fog) kind of light, lay upon the landscape, making the Barrier and the sky merge into one. There was no horizon to be seen." Courtesy of NOAA.

For instance on December 7, for the first time in three days, they could see a few miles around. They had been walking blind in grey twilight, unable to make a sextant observation of the Sun at its zenith since 86 degrees 47 minutes S. Finally, the Sun appeared — "not very brilliant" but "good enough". They caught the Sun at its highest. Then, the question: How good was their dead reckoning for the past three unverified days over "impossible" ground?

They ran the calculations; then looked at each other with "sheer incredulity." 88 degrees 16 minutes S, precisely to a minute the same as their dead reckoning, 88 degrees 16 minutes S. A minute is 101 feet (31 m).

They were nearing the pole (90 degrees S). On December 14, "at three in the afternoon, a simultaneous ‘Halt!’ rang out from the drivers." The drivers had carefully examined their sledge-meters, and the meters showed they had reached the Pole (by dead reckoning), wrote Amundsen. "Of course, every one of us knew that we were not standing on the absolute spot; it would be an impossibility with the time and the instruments at our disposal to ascertain that exact spot."

But they didn’t stop trying. They sneaked up on the pole from there in three steps. See Figure 7. They made camp there (shown as "1" in the figure), at what dead reckoning said was 89 degrees 54 minutes 30 seconds S. Then, they hedged their bet — making darn sure they reached the pole by, in effect, circling it.

Admundsen’s three steps to the South Pole: The symbol "1" on the figure shows where he thought the Pole was by dead reckoning. About this point as center, he established a 12-mi (20-km) circle, which he hoped must capture the true pole. It did. The number "2" shows the camp 6-miles (10 km) further south. "3" shows where Hanssen and Bjaaland walked, another 4 miles (7 km) closer still — within 200 yards (200 m) of the South Pole, it turns out. Idealized drawing by the author.

Step 1. They didn’t have time to make a complete 12-mile-radius (20-km) circle (which they thought would surely do the job) so three brave men (Wisting, Hassel, and Bjaaland) walked (without the good sledge compasses that were too heavy to carry) 12-miles (out of sight) from the camp in three different directions, two at right angles (red and blue lines on Figure 7) to the course that they had been traveling and one continuing the course south (green). Thus, they had the pole surrounded (within their walked triangle, shown purple in the figure). Furthermore, Amundsen and Hanssen took more observations of the Sun there to better establish "south", and to get a better approximation of the South Pole’s location.

Step 2. Then, based on the observations taken in Step 1 and to get even closer for their final observations, they continued on the newly established south course for 6 miles (10 km), and established another camp (shown as "2" in the figure). On December 16 and 17, they took Sun observations with each of their two sextants "every hour through the whole twenty-four." Their observations showed "...we were not on the absolute Pole," but "close." Later a master mathematician verified their sightings: the latitude calculated from these altitude readings was on, the average, 89 degrees 54 minutes S. with a mean error of plus or minus 2 minutes.

They had, however, also established a new south direction and a new approximate Pole location. They weren’t on it yet, and, therefore, could get even closer.

The Fram at the ice edge, January 1912 — ready to go home. Courtesy of NOAA.

Step 3. So finally, Helmer Hanssen and Olav Bjaaland, in order to "come a few inches nearer", walked 4 miles (7 km) south to the Pole. Then, goal reached, back to the good ship, Fram.

Since then, we’ve analyzed the diaries and found the men actually got within 200 meters of the South Pole.

Further Reading:

Roald Amundsen, The South Pole, an account of the Norwegian Antarctic expedition in the Fram, translated from the Norwegian by A.G. Chater, and made available online by The Project Gutenberg.

Peter Ifland, Taking the Stars. Malabar, Florida: Krieger Publishing Company, 1998.

Amundsen’s original South Pole Station by William Spindler, South Pole Station

North Pole Expeditions, Wikipedia

Sextant, Wikipedia

Roald Amundsen, Wikipedia

Navigation, Wikipedia

(Answered Jan. 17, 2006)