- Magnetic north has recently been moving north from Canada to Russia in a cold hurry.
- It's moving about 33 miles a year instead of the usual 7 miles.
- World navigation models had to updated ahead of schedule to catch up with it.
If you're reading this as you travel the arctic, odds are you're probably already a bit confused. Your compass has been, well, strange, lately. That's because magnetic north has been moving. Quickly. It's never been stationary, but recently it's been moving around 485 feet northward toward Siberia every day. That's about 33 miles per year, as opposed to the average 7 miles a year between 1831 and the 1990s, when its pace quickened.
Fortunately, experts say that if you're south of the 55th parallel, you won't notice much of a difference. However, for national defense agencies, commercial airlines, and others that rely on knowing what their compasses are pointing at, it's a much bigger deal. That's why the World Magnetic Model — a set of online reference calculators, software, and technical details — had to be updated recently ahead of schedule instead of waiting for the next planned revision in 2020.
North, north, and north
Image source: Pyty / Shutterstock
There are actually three flavors of north, and they're all in different places.
- Magnetic north — is defined as the location on the Earth's surface where all of its magnetic lines point straight downward. If you look at a compass while you're there, the needle attempts to dip down; that's why it's also called the "dip pole." Magnetic north is always on the move in response to the constant motion of electrical charges in the Earth's liquid outer mantle, which produces Earth's magnetic field.
- Geomagnetic north — is the northern focus of the Earth's magnetosphere, up in the stratosphere. It moves, too, but not nearly as much, since shifts in the Earth's magnetic field are more smoothed-out up there than on the ground. Its location is pretty stable, located above and off the northwest coast of Greenland.
- True north, or geographic north — is the northern terminus of our lines of longitude. It's located in the middle of the Arctic Ocean.
What’s the hurry?
Image source: Johan Swanepoel / Shutterstock
The suddenly accelerating movement of magnetic north has scientists wondering what's up — not because there's any danger we're aware of — because its behavior is one of the few opportunities they have to catch a glimpse of the dynamics inside the earth's molten outer core.
The most prominent theory is that the speed-up is being driven by, as Nature puts it, "liquid iron sloshing within the planet's core." Giant streams of molten iron and nickel continually twist and swirl in the outer core, a pressure cooker that can reach 9,000° F in temperature. The iron is the source of the magnetic fields that comprise the Earth's magnetosphere. The magnetosphere is the barrier that keeps us protected from destructive ultraviolet solar radiation — its existence keeps Earth habitable. Planets with no magnetic barrier are unable to hold onto their atmosphere. Mars lost its magnetosphere 4.2 billion years ago.
Geophysicist Phil Livermore made the case at an American Geophysical Union meeting in Fall 2018 that what we're seeing is the latest action in an ongoing tug of war between two magnetic fields down in the swirling outer core. One is under Siberia, and one is under Canada. Historically, the Canadian field has been winning, keeping magnetic north in Canada. However, there's been a shift, he tells National Geographic, "The Siberian patch looks like it's winning the battle. It's sort of pulling the magnetic field all the way across to its side of the geographic pole."
Some scientists think that the acceleration may be an early sign that Earth's magnetic poles are about to flip, something that happens every every 200,000 to 300,000 years. Others see no evidence of that. Plus, flips occur over thousands of years, so there'd be no cause for alarm anyway.
Keeping an eye on magnetic north
Earth's magnetic lithosphere mapped by Swarm. Image source: ESA
The position of magnetic north is tracked by the European Space Agency's three Swarm satellites orbiting the Earth about 15 times a day — the satellites' readings are continually checked against ground readings to assess the pole's movements. Every five years, until now, at least, scientists have updated the math in the World Magnetic Model, whose goal is to "ensure safe navigation for military applications, commercial airlines, search and rescue operations, and others operating around the North Pole."
Given how things like this tend to play out over geologic time, it would surprise no one if more frequent model updates will be needed going forward.
University of Western Australia's rooftop observatory.
- Researchers from Australia and France team up for a record-breaking laser transmission.
- The new technique avoids atmospheric interference.
- It can be used to test aspects of Einstein's theory of relativity and advance communications.
Scientists achieved the most stable transmission of a laser signal through the atmosphere ever made, beating a world record. The team managed to send laser signals from one point to another while avoiding interference from the atmosphere. Their very precise method can allow for unprecedented comparisons of the flow of time in separate locations. This can enable scientists to carry out new tests of Einstein's celebrated theory of general relativity, and have wide applications across different fields.
For the record transmission, the researchers combined phase stabilization technology with advanced self-guiding optical terminals. They used two identical phase stabilization systems, which had their transmitters located in one building while receivers were in another. One system used optical terminals to send the optical signal over a 265 m free-space path between the buildings. Another system transmitted using a 715 m-long optical fiber cable, essentially to keep tabs on the performance of the free-space link.. The terminals were outfitted with mirrors to prevent interference like phase noise and beam wander.
The scientists hailed from Australia's International Centre for Radio Astronomy Research (ICRAR) and the University of Western Australia (UWA), as well as the French National Centre for Space Studies (CNES) and the French metrology lab Systèmes de Référence Temps-Espace (SYRTE) at Paris Observatory.
The study's lead author Benjamin Dix-Matthews, a Ph.D. student at ICRAR and UWA, highlighted the innovation and potential of their technique. "We can correct for atmospheric turbulence in 3-D, that is, left-right, up-down and, critically, along the line of flight," said Dix-Matthews in a press release. "It's as if the moving atmosphere has been removed and doesn't exist. It allows us to send highly stable laser signals through the atmosphere while retaining the quality of the original signal."
Block diagram of the experimental link that shows two identical phase stabilization systems on the CNES campus. Both of the systems have their transmitter in the Auger building (local site), and both receivers are located in the Lagrange building (remote site). One transmits the optical signal over a 265 m free-space path in-between the buildings while utilizing tip-tilt active optics terminals. The other transmits using 715 m of optical fiber.
Credit: Dix-Matthews, Nature Communications
Dr. Sascha Schediwy, ICRAR-UWA senior researcher, envisioned numerous applications for their technology, whose precise performance beats even the best optical atomic clocks. Putting one of these optical terminals on the ground while another one is on a satellite in space would help the exploration of fundamental physics, according to Schediwy. Other applications could extend to testing Einstein's theories with greater precision as well as understanding the time-related changes of fundamental physical constants and making advanced measurements in earth science and geophysics.
Optical communications, a field that that utilizes light for sending information, could also benefit. The new tech can improve its data rates by "orders of magnitude," thinks Dr. Schediwy. "The next generation of big data-gathering satellites would be able to get critical information to the ground faster," he added.
Check out the new study in Nature Communications.
