理學산책
[스크랩] 최근 지자기 역전현상이 예측!
kongbak
2006. 7. 12. 09:52
 |
| |||||
|
Monday, June 13,2005
| ||||||
|
Our North loses the Pole
After centuries in Canada, the roaming magnetic North Pole has crossed into international waters, en route to Siberia
June 9, 2005 YELLOWKNIFE, N.W.T. - Sometime in the last year, a longtime friend turned its back on Canada and was last spotted heading for Siberia.
For centuries, the magnetic North Pole was ours, a constant companion that wandered the rolling tundra and frozen seas of our Arctic.
But no more.
A Canadian scientist who recently returned from a trip to measure the Pole＇s current location says it has now left Canadian territory and crossed into international waters.
"I think the Pole has probably just moved past the 200-nautical-mile limit," said Larry Newitt, head of the Natural Resources Canada geomagnetic laboratory in Ottawa. "It＇s probably outside of Canada, technically. But we＇re still the closest country to it."
In May, Newitt and his instruments landed on a patch of frozen ocean at 82.5 degrees North to make a more precise measurement of the magnetic Pole＇s position.
The pole, which, unlike the geographic North Pole, is in constant movement, has been within modern Canadian borders since at least the 1600s -- the time of Shakespeare and Sir Isaac Newton.
In 1904 it was measured just off the northern tip of Nunavut＇s King William Island by Norwegian explorer Roald Amundsen, and since then has moved in a north to northwesterly direction at a stately 10 kilometres per year.
But in 2001, scientists discovered that it was picking up the pace, suddenly charging ahead -- and toward the edge of Canadian territory -- at more than 40 kilometres per year.
필자 주(註)
1904년 노르웨이인 아문센이 북극점 정복을 한 이래 매년 10km씩 북서진 해오던 자북극점(磁北極点)이, 2001년을 들어서면서 부터는 캐나다 국경 끝을 향해서 해마다 40km 이상씩 그 이동속도가 높아졌다는 사실을 과학자들이 발견했다는 이야기를 합니다.
This year, bad weather prevented Newitt from reaching the actual location of the pole, and he hasn＇t completed the analysis of his observations. But he got close enough to make two measurements, and says it appears the pole is farther away than expected, and moving even faster than before.
"We landed at two places at around 83 North, and it certainly appears the pole is probably closer to 84 North," he said. "That means that the pole is still continuing to accelerate."
If the pole continues its current course, it will shoot across the top of Earth and end up in Siberia by mid-century.
필자 주(註)
올해 들어서는 자북극이 과학자들이 예상했던 것보다 멀리 떨어져 가면서 이전보다도 더 그 이동 속도가 빨라져서, 북위 83도 근처에서 측정을 시작하였으나, 자북극은 북위 84도 근처에 까지 옮겨가 있는 것처럼 보여지며, 이러한 사실은 자북극에 가속이 붙고 있다는 것, 그래서 지금의 행로를 게속 유지할 경우에는 이 세기 중반까지는 지구꼭대기를 가로질러 시베리아가서 멈추게 될 것이라 예견하고 있습니다.
But the pole＇s movements are difficult to forecast, since its location depends on a terrestrial magnetic field that is produced by extremely complex forces deep inside Earth. Those forces, at their simplest, drive a churning mass of molten iron that rises and falls on convective currents more than 3,000 kilometres below the planet＇s surface. The movement of that iron conducts and produces the magnetic field, whose poles are located fairly close, although still often thousands of kilometres away from, the geographic poles.
Curiously, the speed with which the pole moves could be related to dramatic events like the massive earthquake that caused last December＇s devastating tsunami. That quake was big enough to alter the shape of Earth and jar the planet into a slightly different axis of rotation. It also had enough power to jolt the molten iron that powers the magnetic field, and could be partly responsible for magnetic "jerks" that are propelling the magnetic North Pole, Newitt said.
Scientists have also been intrigued by a weakening in the pole＇s intensity: It has lost 10 per cent of its force in the past few centuries. That could be a sign that the poles are preparing to reverse, a phenomenon that has occurred many times in Earth＇s distant history, said University of Alberta geophysics professor Moritz Heimpel.
필자 주(註)
지난 번 인도네시아의 아체 대지진이 지구를 뒤흔들어 미묘한 지축의 변화와 함께 지구 내부의 용융된 철(외핵)부분에 영향을 끼침으로써 지구의 자북(磁北)의 변화를 가속시키는 원인이 되었을 것이라는 과학자 Newwitt의 언급과 함께 이러한 자북의 세기가 지난 수 백년간 10% 이상 약화되어 왔는데 이것이 과거 지구의 역사에서도 여러 차례 일어났던 지자기 역전현상이 준비되고 있다는 신호가 아닌가 하고 과학자 사이에서 흥미로와 하고 있다고 알버타 대학 지질학과 Moritz Heimpel교수는 언급하고 있습니다.
But the pole＇s continuing movement away from Canadian soil likely won＇t affect anyone, beyond perhaps affecting the northern lights. The magnetic pole draws the charged particles from the sun that create the aurora, and "the people in Fort McMurray might not want it to move away very much," Heimpel said, lest it dim their light shows.
But Canada prides itself on being a northern nation -- it＇s part of that nebulous identity we spend so much time thinking about. Does losing the pole mean losing a piece of ourselves? Will we be launched into the throes of another identity crisis, now that the world＇s compasses no longer point to us?
Carolyn Relf, a geologist with Indian and Northern Affairs, says no.
"As long as Santa＇s still in the North, I don＇t care about the pole," she said.
Besides, there＇s not a whole lot we can do to get it back. The liquid iron that creates Earth＇s magnetic field is located so far beneath the planet＇s crust it＇s beyond the reach of even our most ambitious and patriotic leaders.
Col. Norm Couturier, commanding officer of Canadian Forces Northern Area, is the man charged with protecting Canada＇s Arctic sovereignty -- but guarding the pole is beyond his pay grade.
"It＇s a force of nature that we＇re not equipped to deal with," he said, laughing.
And though Couturier says it is, of course, sad to lose the pole, there is a sunny side. With the pole gone from Canada, it means we have less responsibility for the ill-prepared adventurers who go on half-crazed skiing adventures to reach the magnetic pole.
"It will probably mean now that we＇ll have to stage less rescue missions," he said. "When it was over in Canadian territory, every year we would have to go and assist somebody or recover somebody that was trying to get there.
"Now that it＇s in international waters, a little bit of the pressure is off us."
Still, it could be just a temporary reprieve. The forces that are pushing the pole away from us could just as easily pull it back inside Canadian borders one day.
"I＇m sure we can share it for a little while. But it＇s coming back," said a hopeful James Pugsley, president of Yellowknife＇s Astronomy North.
"We did such a good job of managing it while it was here. It will be back."
WHY IT MATTERS
In an age of satellites and computer technology, why do we still care about the magnetic North Pole anyway?
For most of human history, we needed the pole for navigation, since compasses pointed to it and directed us north. But satellite-based navigation, using GPS (global positioning system) devices, has gained near-universal acceptance in planes and ships.
Doesn＇t that make compasses a relic of the past? Hardly, says Larry Newitt, the Canadian geophysicist who measures the pole＇s location. Figuring out exactly where the pole is allows map-makers to draw what＇s called "magnetic declination," which is the number of compass degrees that separate the direction of magnetic north from True North, which points to the geographic North Pole.
In Edmonton, the magnetic declination is about 17 degrees to the east.
And as it turns out, everyone from boy scouts to workers drilling for oil still depend on compasses -- and need to know the magnetic declination to be able to navigate accurately.
The reason is that GPS calculates direction by calculating movement. So if your location at point B is due west of your location at point A, you＇re moving west. But it doesn＇t work well for slow-moving objects, such as hikers and canoeists, or for sophisticated directional drills, the kind used to hunt for oil in northern Alberta.
"People who do directional drilling in the oilpatch essentially use compasses down behind the drill bit to determine the direction they＇re going to drill if they＇re drilling horizontal wells," Newitt said.
And, surprisingly, many of those high-tech gadgets that we install today, such as satellite dishes and solar panels, also use magnetic compasses to point themselves in the right direction.
Ran with fact box "Why It Matters", which has been appendedto this story. © The Edmonton Journal 2005 | ||||||
출처 : 최근 지자기 역전현상이 예측!
글쓴이 : 깨어있는 마음 원글보기
메모 :