Compasses at Greenwich are about to do something not observed for 360 years

Credit: JS Pailly

What a time to be alive says ScienceAlert.
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For the first time in centuries, compasses in Greenwich are about to point directly at true north: an epic coincidence of time and magnetism that hasn’t taken place for some 360 years.

This serendipitous occurrence – which is set to occur within the next fortnight – serves as a startling reminder of how Earth’s magnetic north pole is constantly wandering, unlike the fixed ‘true north’ of Earth’s geographic north pole.

The angular difference between those two different points is called magnetic declination, and while the gap might not be something ordinary people spend a great deal of time thinking about, it’s a disparity that can last for centuries at a time.

For hundreds of years now in the UK, due to Earth’s shifting magnetic north pole, declination has been negative, meaning compass needles have been pointing west of true north.

But nothing lasts forever.

Earth’s mantle is magnetic, researchers find

Still plenty of work for scientists to do to gain a better understanding of our rotating Earth’s electromagnetic processes.

Scientists assumed Earth’s mantle, the layer stretching from the crust to a depth of 255 miles, was magnetically dead. New research suggests they were mistaken, reports Phys.org.

Most scientists thought Earth’s magnetism was powered by materials in the crust and core, but according to a new study published this week in the journal Nature, hematite, a common iron oxide, retains its magnetic qualities at high temperatures.

“This new knowledge about the Earth’s mantle and the strongly magnetic region in the western Pacific could throw new light on any observations of the Earth’s magnetic field,” Ilya Kupenko, mineral physicist and researcher from the University of Munster in Germany, said in a news release.

Space weather events linked to nuclear testing

One high-altitude nuclear test even managed to create its own artificial aurora. Others knocked out orbiting satellites.

Our Cold War history is now offering scientists a chance to better understand the complex space system that surrounds us, says Phys.org.

Space weather — which can include changes in Earth’s magnetic environment— is usually triggered by the sun’s activity, but recently declassified data on high-altitude nuclear explosion tests have provided a new look at the mechanisms that set off perturbations in that magnetic system.

Such information can help support NASA’s efforts to protect satellites and astronauts from the natural radiation inherent in space. From 1958 to 1962, the U.S. and U.S.S.R. ran high-altitude tests with exotic code names like Starfish, Argus and Teak.

The tests have long since ended, and the goals at the time were military. Today, however, they can provide crucial information on how humans can affect space.

Changes to Earth’s magnetic field recorded in 600-year-old Judean pottery

Kingdom of Judah [credit: IB Times]

The ‘two Iron Age spikes’ in magnetism could be worth investigating further.

Ancient clay jar handles can act as a record of the Earth’s magnetic history, a new study finds, confirming evidence of sudden, sharp spikes in the strength of the field, as the IB Times reports.

Fragments of pottery were historically stamped with an emblem of the rulers of the Kingdom Judah, which encompassed Jerusalem and nearby areas. These jars were also marked by the state of the Earth’s geomagnetic field at its time of construction, offering researchers a unique chance to reconstruct the past of the Earth’s magnetic field.

The study is based on the technique of archaeomagnetism. Some minerals in clay are magnetic, and before they are heated they are aligned randomly. As the pottery is heated during the firing process, the magnetic particles tend to align with the Earth’s magnetic field. The stronger the magnetic field, the greater the degree of alignment in the magnetic minerals.

What did Earth’s ancient magnetic field look like?

Credit: NASA

Whether or not dynamo theories are sound, this research highlights historic variability in Earth’s magnetic field behaviour and could have ‘widespread implications’. Phys.org reporting.

New work from Carnegie’s Peter Driscoll suggests Earth’s ancient magnetic field was significantly different than the present day field, originating from several poles rather than the familiar two. It is published in Geophysical Research Letters.

Swarm tracks Earth’s turbulent magnetic field

Earth’s magnetosphere [image credit: SPL / BBC]

The BBC report by Jonathan Amos includes two ‘blink-and-you-miss-it’ videos that offer a global view of the magnetic patterns. The three-year east-west oscillation sounds interesting.

Europe’s Swarm mission is providing an unprecedented view of Earth’s turbulent magnetic field, scientists say. The three-satellite constellation is now routinely mapping its convulsions, allowing researchers to probe the mechanisms that drive the “invisible shield” in remarkable new detail.

Major earthquake hits Nepal

Earthquake zone [credit: BBC]

BBC reports: Several thousand* people [*last Talkshop update: 28 April] are known to have died in a powerful earthquake that struck Nepal, wrecking many historic buildings, officials have said.

The quake measured 7.9 and struck an area between the capital Kathmandu and the city of Pokhara, the US Geological Survey said.

Tremors were felt across the region, as far afield as Pakistan, Bangladesh and neighbouring India.

A Nepali minister said there had been “massive damage” at the epicentre.

Report (on first day of ‘quake): Nepal earthquake: More than 100 dead, many injured – BBC News.

Big earthquakes generally occur at low sunspot numbers

Location		Date	Magnitude2
1.	Chile	May 22, 1960	9.5
2.	Prince William Sound, Alaska	March 28, 19643	9.2
3.	Andreanof Islands, Aleutian Islands	March 9, 1957	9.1
4.	Japan	March 11, 2011	9.0
5.	Kamchatka	Nov. 4, 1952	9.0
6.	Off western coast of Sumatra, Indonesia	Dec. 26, 2004	9.0
7.	Off the coast of Ecuador	Jan. 31, 1906	8.8
8.	Offshore Maule, Chile	Feb. 27, 2010	8.8
9.	Rat Islands, Aleutian Islands	Feb. 4, 1965	8.7
10.	Northern Sumatra, Indonesia	March 28, 2005	8.7

Here’s a rough plot of these biggest quakes against sunspot number

Mr Vukevic offers a resource

Our friend Vukevic called by and gave me a pointer to a links page at his site which provides a resource for those interested in studying planetary, solar and magnetic phenomena.

http://www.vukcevic.co.uk/GandF.htm

Here’s an example demonstrating the match between the sunspot number and Vuk’s planetary motion derived formulas:

Hopefully, Vuk will call back to give us some further info on his research.

North magnetic pole position shifts

Here’s another interesting correlation. The Position of the north magnetic pole has been shifting rapidly over the last several decades. The rate of change of it’s declination correlates with the variations in Earth’s length of day and the motion of the sun relative to the centre of mass of the solar system which we discussed in my first post.

North Pole rate of change of declination vs LOD vs SSBz

More interesting information on Earth’s magnetism and it’s relationship with the sun here: http://www.appinsys.com/GlobalWarming/EarthMagneticField.htm

If the changes in Length of Day are related to changes in the circulation of currents of molten material beneath the Earth’s crust, we could speculate that magnetic  iron ores are shifting their predominant accumulations and this affects the location of the magnetic north pole.