Earth’s magnetic shield booms like a drum when hit by impulses –

Earth’s magnetic shield booms like a drum when hit by impulses –
February 12, 2019, Queen Mary, University of London

Artist rendition of a plasma jet impact (yellow) generating standing waves at the magnetopause boundary (blue) and in the magnetosphere (green). The outer group of four THEMIS probes witnessed the flapping of the magnetopause over each satellite in succession, confirming the expected behaviour/frequency of the theorised magnetopause eigenmode wave. Credit: E. Masongsong/UCLA, M. Archer/QMUL, H. Hietala/UTU

The Earth’s magnetic shield booms like a drum when it is hit by strong impulses, according to new research from Queen Mary University of London.

As an impulse strikes the outer boundary of the shield, known as the magnetopause, ripples travel along its surface which then get reflected back when they approach the magnetic poles.

The interference of the original and reflected waves leads to a standing wave pattern, in which specific points appear to be standing still while others vibrate back and forth. A drum resonates like this when struck in exactly the same way.

This study, published in Nature Communications, describes the first time this effect has been observed after it was theoretically proposed 45 years ago.

Movements of the magnetopause are important in controlling the flow of energy within our space environment with wide-ranging effects on space weather, which is how phenomena from space can potentially damage technology like power grids, GPS and even passenger airlines.

The discovery that the boundary moves in this way sheds light on potential global consequences that previously had not been considered.

Dr. Martin Archer, space physicist at Queen Mary University of London, and lead author of the paper, said: “There had been speculation that these drum-like vibrations might not occur at all, given the lack of evidence over the 45 years since they were proposed. Another possibility was that they are just very hard to definitively detect.

NASA’s THEMIS mission proves a 45-year-old theory that the outer boundary of Earth’s magnetic field vibrates like a drum. Credit: Martin Archer, Queen Mary University of London

“Earth’s magnetic shield is continuously buffeted with turbulence so we thought that clear evidence for the proposed booming vibrations might require a single sharp hit from an impulse. You would also need lots of satellites in just the right places during this event so that other known sounds or resonances could be ruled out. The event in the paper ticked all those quite strict boxes and at last we’ve shown the boundary’s natural response.”

The researchers used observations from five NASA THEMIS satellites when they were ideally located as a strong isolated plasma jet slammed into the magnetopause. The probes were able to detect the boundary’s oscillations and the resulting sounds within the Earth’s magnetic shield, which agreed with the theory and gave the researchers the ability to rule out all other possible explanations.

Many impulses which can impact our magnetic shield originate from the solar wind, charged particles in the form of plasma that continually blow off the Sun, or are a result of the complicated interaction of the solar wind with Earth’s magnetic field, as was technically the case for this event.

The signals recorded by the THEMIS probes converted to audible sound. Credit: Martin Archer, Queen Mary University of London

The interplay of Earth’s magnetic field with the solar wind forms a magnetic shield around the planet, bounded by the magnetopause, which protects us from much of the radiation present in space.

Other planets like Mercury, Jupiter and Saturn also have similar magnetic shields and so the same drum-like vibrations may be possible elsewhere.

Further research is needed to understand how often the vibrations occur at Earth and whether they exist at other planets as well. Their consequences also need further study using satellite and ground-based observations.

Explore further:
School students identify sounds caused by solar storm

More information:
‘Direct Observations Of A Surface Eigenmode Of The Dayside Magnetopause’. M.O. Archer, H. Hietala, M.D. Hartinger, F. Plaschke, V. Angelopoulos. Nature Communications (2019). DOI: 10.1038/s41467-018-08134-5

Related Stories

School students identify sounds caused by solar storm

October 17, 2018

School students have successfully identified sounds caused by a solar storm in the Earth’s magnetic shield, as part of a Queen Mary University of London research project.

Mercury’s magnetic field measured by MESSENGER orbiter

May 15, 2012

Researchers working with NASA’s Mercury Surface, Space Environment, Geochemistry, and Ranging (MESSENGER) spacecraft report the frequent detections of Kelvin-Helmholtz (KH) waves at the edge of the innermost planet’s magnetosphere. …

Magnetic pumping pushes plasma particles to high energies

November 5, 2018

As you walk away from a campfire on a cool autumn night, you quickly feel colder. The same thing happens in outer space. As it spins, the sun continuously flings hot material into space, out to the furthest reaches of our …

Earth’s magnetosphere behaves like a sieve

October 24, 2012

ESA’s quartet of satellites studying Earth’s magnetosphere, Cluster, has discovered that our protective magnetic bubble lets the solar wind in under a wider range of conditions than previously believed.

A stellar achievement: Magnetized space winds in the laboratory

November 5, 2018

New insights have been gained about stellar winds, streams of high-speed charged particles called plasma that blow through interstellar space. These winds, created by eruptions from stars or stellar explosions, carry with …

Taking a spin on plasma space tornadoes with NASA observations

November 17, 2017

Interplanetary space is hardly tranquil. High-energy charged particles from the Sun, as well as from beyond our solar system, constantly whizz by. These can damage satellites and endanger astronaut health—though, luckily …

Recommended for you

Van Allen probes begin final phase of exploration in Earth’s radiation belts

February 12, 2019

Two tough, resilient, NASA spacecraft have been orbiting Earth for the past six and a half years, flying repeatedly through a hazardous zone of charged particles around our planet called the Van Allen radiation belts. The …

Gory, freaky, cool: Marine snail venom could improve insulin for diabetic patients

February 12, 2019

Although moderately mobile, marine cone snails have perfected several strategies to capture prey. Some fish-hunting species release venom into the surrounding water. Within the plume of toxic venom, the fish succumbs to fast-acting …

Hyperbolic metamaterials enable nanoscale ‘fingerprinting’

February 12, 2019

Hyperbolic metamaterials are artificially made structures that can be formed by depositing alternating thin layers of a conductor such as silver or graphene onto a substrate. One of their special abilities is supporting the …

Ancient spider fossils, surprisingly preserved in rock, reveal reflective eyes

February 12, 2019

Usually, soft-bodied species like spiders aren’t fossilized in rock like animals with bones and teeth. More often, ancient spiders and insects are more likely to be discovered preserved in amber.

New method of fertilizer production can better suit the needs of farms in Africa and around the globe

February 12, 2019

Nitrogen, phosphorous, and potassium are the three elements that support the productivity of all plants used for agriculture, and are the constituents of commercial fertilizers that farmers use throughout the world.

Universal basic income experiment made people happier but not more likely to get a job

February 12, 2019

Finland’s Social Insurance Institution (FSII) has published the results of an income experiment it carried out for two years to learn more about ways to reduce unemployment. They report that their experiment showed that giving …

James Clerk Maxwell Telescope discovers flare 10 billion times more powerful than those on the sun

February 12, 2019

The Hawaii-based James Clerk Maxwell Telescope (JCMT) has discovered a stellar flare 10 billion times more powerful than the Sun’s solar flares, a history-making discovery that could unlock decades-old questions about the …


Read More