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 Six-decade-old space mystery solved with shoebox-sized satellite called a CubeSat
15.12.2017 | National Science Foundation

nachricht NSF-funded researchers find that ice sheet is dynamic and has repeatedly grown and shrunk
15.12.2017 | National Science Foundation

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: First-of-its-kind chemical oscillator offers new level of molecular control

DNA molecules that follow specific instructions could offer more precise molecular control of synthetic chemical systems, a discovery that opens the door for engineers to create molecular machines with new and complex behaviors.

Researchers have created chemical amplifiers and a chemical oscillator using a systematic method that has the potential to embed sophisticated circuit...

Im Focus: Long-lived storage of a photonic qubit for worldwide teleportation

MPQ scientists achieve long storage times for photonic quantum bits which break the lower bound for direct teleportation in a global quantum network.

Concerning the development of quantum memories for the realization of global quantum networks, scientists of the Quantum Dynamics Division led by Professor...

Im Focus: Electromagnetic water cloak eliminates drag and wake

Detailed calculations show water cloaks are feasible with today's technology

Researchers have developed a water cloaking concept based on electromagnetic forces that could eliminate an object's wake, greatly reducing its drag while...

Im Focus: Scientists channel graphene to understand filtration and ion transport into cells

Tiny pores at a cell's entryway act as miniature bouncers, letting in some electrically charged atoms--ions--but blocking others. Operating as exquisitely sensitive filters, these "ion channels" play a critical role in biological functions such as muscle contraction and the firing of brain cells.

To rapidly transport the right ions through the cell membrane, the tiny channels rely on a complex interplay between the ions and surrounding molecules,...

Im Focus: Towards data storage at the single molecule level

The miniaturization of the current technology of storage media is hindered by fundamental limits of quantum mechanics. A new approach consists in using so-called spin-crossover molecules as the smallest possible storage unit. Similar to normal hard drives, these special molecules can save information via their magnetic state. A research team from Kiel University has now managed to successfully place a new class of spin-crossover molecules onto a surface and to improve the molecule’s storage capacity. The storage density of conventional hard drives could therefore theoretically be increased by more than one hundred fold. The study has been published in the scientific journal Nano Letters.

Over the past few years, the building blocks of storage media have gotten ever smaller. But further miniaturization of the current technology is hindered by...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

See, understand and experience the work of the future

11.12.2017 | Event News

Innovative strategies to tackle parasitic worms

08.12.2017 | Event News

AKL’18: The opportunities and challenges of digitalization in the laser industry

07.12.2017 | Event News

 
Latest News

Engineers program tiny robots to move, think like insects

15.12.2017 | Power and Electrical Engineering

One in 5 materials chemistry papers may be wrong, study suggests

15.12.2017 | Materials Sciences

New antbird species discovered in Peru by LSU ornithologists

15.12.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>