Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Magnetic ’slinky effect’ may power aurora

17.01.2003


The spectacular aurora borealis displays that light up the northern nights could be powered by a gigantic "slinky" effect in Earth’s magnetic field lines, according to research performed at the University of Minnesota. Earth’s magnetic field resemble a slinky in that when "wiggled," it undulates in waves that travel down the field lines at speeds up to 25 million miles per hour. These waves can pass energy to electrons, accelerating them along the magnetic field lines toward Earth. When the electrons hit atoms in the atmosphere, the atoms become excited and produce the colors of the aurora. Using electric and magnetic field data and images from NASA’s POLAR satellite, the researchers showed that energy from such waves is sufficient to power auroras and that statistically, the waves occur in the same locations as auroras--in a ring around the poles. The work will be published in the Jan. 17 issue of Science.




"We don’t know exactly what wiggles the field lines, but similar processes could explain the heating of the solar corona [the sun’s atmosphere], the release of energy during solar flares and the acceleration of the solar wind [a stream of charged particles from the sun]," said physics associate professor John Wygant, second author of the study. "At the edges of sunspots, other researchers have actually seen magnetic field lines waving. Understanding how such waves are caused and how they transmit energy is important to unraveling the complex processes behind larger-scale particle accelerations that occur, for example, in jets of material being ejected from black holes at the centers of galaxies." The paper’s first author is Andreas Keiling, who headed the study while a doctoral student and, later, a research scientist at the University of Minnesota. He is now at the Center for Space Research on Radiation in Toulouse, France.

The ultimate source of energy for auroras is the solar wind. Flowing with the wind--which is mostly single protons and electrons--is a magnetic field that encounters Earth’s own field tens of thousands of miles above the planet surface. Earth is like a huge bar magnet, with magnetic field lines coming out near the poles, curving through space, and re-entering near the opposite pole. When the solar wind’s magnetic field sweeps by, it joins with some of Earth’s magnetic field lines and stretches them into space on the night side of Earth. The stretching energizes this part of the magnetic field until it suddenly "snaps" away from the solar wind and reconnects with Earth. This process, called reconnection, may send waves rippling through the magnetic field, like wiggling a slinky, said Wygant.


Energy from the waves then passes to electrons, sending them in beams along the magnetic field lines into the atmosphere. The color of the aurora depends on how deeply the electrons penetrate the atmosphere and which atoms they excite. Measurements of electrical energy at altitudes near 12,000 miles, where the electrons are accelerated, showed sufficient energy from the waves to power auroras, Wygant said.

Auroras also occur in south polar regions, where they are known as the aurora australis. Waves in the magnetic field lines are called Alfven waves, after Hannes Alfven, a Swedish physicist who helped found the field of plasma physics, said Wygant.

POLAR’s electric field measurements were performed by an instrument built by the University of California at Berkeley. Other authors of the paper are Cynthia Cattell, physics professor, University of Minnesota; Forrest Mozer, professor of physics, Berkeley; and Christopher Russell, professor of physics, UCLA. The work was supported by NASA.



POLAR satellite images of the auroral ring are at www1.umn.edu/urelate/newsservice/aurora.html.

Contacts:
John Wygant, (510) 642-7297 (Jan. 13 and 14), (612) 626-8921 (Jan. 15 and later)
Cynthia Cattell, (612) 626-8918 (until noon Jan. 15)
Andreas Keiling, 33 (0) 561 55 66 60 (Toulouse, France)
Deane Morrison, University News Service, (612) 624-2346


Deane Morrison | EurekAlert!
Further information:
http://www.umn.edu/
http://www1.umn.edu/urelate/newsservice/aurora.html

More articles from Earth Sciences:

nachricht NASA finds newly formed tropical storm lan over open waters
17.10.2017 | NASA/Goddard Space Flight Center

nachricht The melting ice makes the sea around Greenland less saline
16.10.2017 | Aarhus University

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Neutron star merger directly observed for the first time

University of Maryland researchers contribute to historic detection of gravitational waves and light created by event

On August 17, 2017, at 12:41:04 UTC, scientists made the first direct observation of a merger between two neutron stars--the dense, collapsed cores that remain...

Im Focus: Breaking: the first light from two neutron stars merging

Seven new papers describe the first-ever detection of light from a gravitational wave source. The event, caused by two neutron stars colliding and merging together, was dubbed GW170817 because it sent ripples through space-time that reached Earth on 2017 August 17. Around the world, hundreds of excited astronomers mobilized quickly and were able to observe the event using numerous telescopes, providing a wealth of new data.

Previous detections of gravitational waves have all involved the merger of two black holes, a feat that won the 2017 Nobel Prize in Physics earlier this month....

Im Focus: Smart sensors for efficient processes

Material defects in end products can quickly result in failures in many areas of industry, and have a massive impact on the safe use of their products. This is why, in the field of quality assurance, intelligent, nondestructive sensor systems play a key role. They allow testing components and parts in a rapid and cost-efficient manner without destroying the actual product or changing its surface. Experts from the Fraunhofer IZFP in Saarbrücken will be presenting two exhibits at the Blechexpo in Stuttgart from 7–10 November 2017 that allow fast, reliable, and automated characterization of materials and detection of defects (Hall 5, Booth 5306).

When quality testing uses time-consuming destructive test methods, it can result in enormous costs due to damaging or destroying the products. And given that...

Im Focus: Cold molecules on collision course

Using a new cooling technique MPQ scientists succeed at observing collisions in a dense beam of cold and slow dipolar molecules.

How do chemical reactions proceed at extremely low temperatures? The answer requires the investigation of molecular samples that are cold, dense, and slow at...

Im Focus: Shrinking the proton again!

Scientists from the Max Planck Institute of Quantum Optics, using high precision laser spectroscopy of atomic hydrogen, confirm the surprisingly small value of the proton radius determined from muonic hydrogen.

It was one of the breakthroughs of the year 2010: Laser spectroscopy of muonic hydrogen resulted in a value for the proton charge radius that was significantly...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

ASEAN Member States discuss the future role of renewable energy

17.10.2017 | Event News

World Health Summit 2017: International experts set the course for the future of Global Health

10.10.2017 | Event News

Climate Engineering Conference 2017 Opens in Berlin

10.10.2017 | Event News

 
Latest News

Researchers release the brakes on the immune system

18.10.2017 | Health and Medicine

Separating methane and CO2 will become more efficient

18.10.2017 | Life Sciences

Ocean atmosphere rife with microbes

17.10.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>