Sunday, January 30, 2011

Earth's Magnetic Field Shifts, Forcing Airport Runway Change



Earth's Magnetic Field Shifts, Forcing Airport Runway Change

Hi there. I notice you're flying past the doughnuts. Grab one for both of us, would you? Off the virtual top shelf so they're the low fat ones, okay? Better snag them before Madge moves the tray on you.

Things are always moving around here. Now, even North isn't really North anymore. Can you believe that? The magnetic north pole is currently hovering over the North Sea and moving toward Siberia . This means two Florida airports are renumbering their runways.

Odd as this connection may appear on the surface, the adjustments under way at Tampa International Airport and beginning next week at Peter O'Knight Airport are the result of a natural, ongoing process.

Earth's magnets

The Earth has an iron core, and movement within its outer part is likely responsible for sustaining a magnetic field, which constitutes much of what we measure at the Earth's surface. As a result, the Earth resembles something of a giant magnet with two poles: magnetic north and magnetic south. However, its field is not perfectly symmetrical and has undulations that are always moving around, according to Jeffrey Love, a research scientist with the U.S. Geological Survey's Geomagnetism Program.

The magnetic poles don't line up with the geographic ones, and the difference between them is an angle called declination . As if this wasn't enough of a nuisance for navigators, the Earth's magnetic field drifts, causing the angle of declination to change over time.

In fact, it drifts about one-fifth of a degree a year at lower latitudes, such as Florida . "So that means if you wait five years, the compass will be off by one degree," Love said.

For long-distance air travel, an error of only a couple of degrees could translate to arriving in the wrong airport, Love said. Yeah, like you get on a flight going to Miami and end up in Vladivostok, eh. “Oops,” said the pilot!

Runways are designated according to the points on a compass, and the drifting magnetic north means that they, periodically, need to be renamed.

Maybe that's what happened to my luggage, eh!

Bob

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