Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Unveiling the aurora

12.12.2001


The Northern Lights: powered by an immense electrical circuit.
© Corbis


Satellites have detected the shifting forces that weave the Northern Lights.

A group of four spacecraft has given scientists their first glimpse of the immense electrical circuit above the Earth that creates the shimmering veil of the aurora borealis, or Northern Lights1.

In January 2001 the four satellites of the European Space Agency’s Cluster mission encountered a beam of electrons moving away from the Earth near the North Pole. The beam was on the outward-bound leg of its journey from the Sun, through the Earth’s atmosphere - where it creates the aurora - and back into space.



Passing through the beam in close succession, the satellites recorded it growing and vanishing over 200 seconds, Goran Marklund of the Royal Institute of Technology in Stockholm, Sweden, and co-workers report. Such fluctuations leave their mark in the shifting curtains of the spectacular display over the North Pole.

Auroral displays happen when the solar wind - the stream of electrically charged particles ejected from the Sun - penetrates the ionosphere, the region of the Earth’s upper atmosphere between 80 and 200 km above the ground. The edge of the planet’s magnetic field deflects most of the solar wind. But the field lines channel some particles down towards the poles.

The particles collide with molecules in the atmosphere above the North Pole, producing the glow of the aurora borealis.

The particles streaming down from the Sun are mostly negatively charged electrons. The funnel-shaped electric field at the North Pole focuses these electrons into a kind of beam. This beam generates the aurora when it enters the ionosphere, which is rich in charged particles.

Beam up

But the electrons must keep moving. The beam gets bent sideways in the auroral region so that it runs parallel to the Earth’s surface, before turning upward and streaming back into space.

It has long been thought that another, positively charged electric field draws the electrons up from the ionosphere and fires them back into space. According to this idea, the aurora is a consequence of this vast electrical circuit, in which electrons flow from a negative to a positive terminal, like those of a battery.

The aurora owes its ever-changing beauty to the inconstancy of the circuit. Solar winds ’beat’ the magnetic fields, causing them to flicker on and off.

Cluster consists of four satellites launched in 2000 - Rumba, Salsa, Samba and Tango - that orbit between 19,000 and 119,000 kilometres above the Earth, passing in and out of the planet’s magnetic field.

Previous spacecraft have detected the upward flow of electrons. But it hasn’t been possible to follow how the beam changes over time. The Cluster mission can study this because the four satellites, orbiting in formation, pass through the same region of the magnetic field at different times.

The upward beam of electrons creates a kind of ’anti-aurora’ or black aurora, sometimes visible from the ground as black patches or rings in the Northern Lights.

References

  1. Marklund, G. T. et al. Temporal evolution of the electric field accelerating the electrons away from the auroral ionosphere. Nature, 414, 724 - 727, (2001).

PHILIP BALL | © Nature News Service

More articles from Physics and Astronomy:

nachricht NASA laser communications to provide Orion faster connections
30.03.2017 | NASA/Goddard Space Flight Center

nachricht Pinball at the atomic level
30.03.2017 | Max-Planck-Institut für Struktur und Dynamik der Materie

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

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

Im Focus: A Challenging European Research Project to Develop New Tiny Microscopes

The Institute of Semiconductor Technology and the Institute of Physical and Theoretical Chemistry, both members of the Laboratory for Emerging Nanometrology (LENA), at Technische Universität Braunschweig are partners in a new European research project entitled ChipScope, which aims to develop a completely new and extremely small optical microscope capable of observing the interior of living cells in real time. A consortium of 7 partners from 5 countries will tackle this issue with very ambitious objectives during a four-year research program.

To demonstrate the usefulness of this new scientific tool, at the end of the project the developed chip-sized microscope will be used to observe in real-time...

Im Focus: Giant Magnetic Fields in the Universe

Astronomers from Bonn and Tautenburg in Thuringia (Germany) used the 100-m radio telescope at Effelsberg to observe several galaxy clusters. At the edges of these large accumulations of dark matter, stellar systems (galaxies), hot gas, and charged particles, they found magnetic fields that are exceptionally ordered over distances of many million light years. This makes them the most extended magnetic fields in the universe known so far.

The results will be published on March 22 in the journal „Astronomy & Astrophysics“.

Galaxy clusters are the largest gravitationally bound structures in the universe. With a typical extent of about 10 million light years, i.e. 100 times the...

Im Focus: Tracing down linear ubiquitination

Researchers at the Goethe University Frankfurt, together with partners from the University of Tübingen in Germany and Queen Mary University as well as Francis Crick Institute from London (UK) have developed a novel technology to decipher the secret ubiquitin code.

Ubiquitin is a small protein that can be linked to other cellular proteins, thereby controlling and modulating their functions. The attachment occurs in many...

Im Focus: Perovskite edges can be tuned for optoelectronic performance

Layered 2D material improves efficiency for solar cells and LEDs

In the eternal search for next generation high-efficiency solar cells and LEDs, scientists at Los Alamos National Laboratory and their partners are creating...

Im Focus: Polymer-coated silicon nanosheets as alternative to graphene: A perfect team for nanoelectronics

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are less stable. Now researchers at the Technical University of Munich (TUM) have, for the first time ever, produced a composite material combining silicon nanosheets and a polymer that is both UV-resistant and easy to process. This brings the scientists a significant step closer to industrial applications like flexible displays and photosensors.

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

International Land Use Symposium ILUS 2017: Call for Abstracts and Registration open

20.03.2017 | Event News

CONNECT 2017: International congress on connective tissue

14.03.2017 | Event News

ICTM Conference: Turbine Construction between Big Data and Additive Manufacturing

07.03.2017 | Event News

 
Latest News

'On-off switch' brings researchers a step closer to potential HIV vaccine

30.03.2017 | Health and Medicine

Penn studies find promise for innovations in liquid biopsies

30.03.2017 | Health and Medicine

An LED-based device for imaging radiation induced skin damage

30.03.2017 | Medical Engineering

VideoLinks
B2B-VideoLinks
More VideoLinks >>>