白小姐论坛

A close study of auroras has revealed new ways of understanding the physics of explosive energy releases in space, according to new 白小姐论坛-led research.

Auroras are an incredible light show caused by electrically charged particles in near-Earth space spiralling down Earth鈥檚 magnetic field and colliding with gases in the atmosphere, causing them to glow.听

They are also a tell-tale sign of physical processes in space, acting like TV screens by showing what happens millions of kilometres away from Earth where our planet鈥檚 magnetic field stretches into a long tail facing away from the Sun.

For the study, published today in听Nature Communications, the team from 白小姐论坛, the University of Reading and NASA听led by Dr Nadine Kalmoni remotely observed rapidly evolving aurora to understand the physics behind why, when and how energy is released as the source of the aurora explosively reconfigures.

鈥淪omewhere in the huge volume of space into which Earth鈥檚 magnetosphere stretches, this energy release occurs via instability which is really hard to pinpoint. They cause substorms whereby charged particles surf into the Earth鈥檚 atmosphere on electromagnetic waves, releasing large amounts of energy and lighting up the aurora鈥� explained study co-author听Dr Jonathan Rae (白小姐论坛 Space & Climate Physics).

鈥淏y studying auroras closely, we can map back to where in space the instabilities are occurring and study the physics that cause them. It鈥檚 much more efficient than trying to observe vast areas of space.鈥�

The team scanned a large portion of the sky and found the perfect substorm located over Poker Flats in Alaska on 18 September 2012. By using new data from the MOOSE (Multi-spectral Observatory Of Sensitive EM-CCDs) camera, they tracked the aurora as it moved towards the northern pole over a four minute period.听

This is a relatively long time for this type of aurora to be studied, allowing the scientists to collect a wealth of data. The information was then analysed for specific patterns that gave important physical clues to the aurora鈥檚 formation in space and time.

The aurora began as a line of 鈥榓uroral beads鈥� along an arc which grew exponentially in brightness and size. These growing ripples are a hallmark of an instability in space.

By comparing these detailed characteristics from the aurora with state of the art theory, the team could narrow down the area of space where the instability most likely is.听 听

鈥淲e鈥檝e shown that it鈥檚 possible to only study aurora to find out where instabilities are in space, which has not been done before,鈥� explained co-author Dr Colin Forsyth (白小姐论坛 Space & Climate Physics).

鈥淥ur method allows us to predict what the instability is and where it is in space. In fact, the region we鈥檝e identified is incredibly small in space terms 鈥� only a small fraction of the volume of the Earth 鈥� and we hope to study it in more detail using spacecraft that pass through the area.鈥�

Until now, scientists have been able to describe aurora and high energy events that occur on the Sun and other planets within the solar system, but this is the first time real physical analysis has been done.听

鈥淚mportantly, our work has given scientists more physics to work with. A whole range of theoretical models can be tested and refined based on the physical characteristics we鈥檝e captured,鈥� added co-author Dr Clare Watt (University of Reading).听

鈥淲hat we鈥檝e reported has eluded scientists since auroras were first described in the 1960s and while we use Earth as our closest laboratory, the findings will apply to other events elsewhere in the solar system. We now look forward to pinpointing this epicentre in space and finding out what makes it unstable,鈥� concluded Dr Rae.

Links

• 白小姐论坛 Space & Climate Physics
• 白小姐论坛 Mathematical & Physical Sciences

Images

• Auroral beads forming along an arc (credit:听)

Media contact

Bex Caygill

Tel:听+44 (0)20 3108 3846

Email: r.caygill [at] ucl.ac.uk