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Predicting solar storm
arrival at Earth

Posted: 14 April

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Many of the talks in today’s solar sessions at the National Astronomy Meeting focused on predicting the timing and effects of solar flares on the Earth. This ‘space weather’ can wipe out power grids and communications on our vulnerable planet and is therefore a vital area of space research.

In one talk, scientists from the University of Leicester presented a technique to predict when blasts of solar wind will reach Earth, Venus and Mars using NASA’s STEREO and ACE satellites.

A mosaic of the extreme ultraviolet images from the STEREO Ahead observatory's SECCHI/Extreme Ultraviolet Imaging Telescope taken on 4 December 2006, its first day of imaging. Image: STEREO (NASA).

The team focused on Coronal Interaction Regions (CIRs), high pulses of solar wind that arise when fast moving solar wind particles spewing out of a coronal hole catch a slower flow ahead and the plasma becomes compressed. When these CIRs collide with the upper layers of planetary atmospheres, they invoke high levels of activity manifesting as a high-density area of plasma followed by a region of increased windspeed.

Using the twin STEREO spacecraft, the ACE solar monitoring spacecraft, Mars Express and Venus Express, the Leicester team monitored some 30 CIR events during the period 1 July 2007 to 31 August 2008 on their journey from the Sun to Venus and Mars, tracking their speed and direction.

"Our estimates from ACE and STEREO are in good agreement with data from Mars Express,” says Anthony Williams, who presented the results today. “However, by the time these in-situ measurements are made, the CIRs are already crossing the Earth's orbital path. To develop a good forecasting system, we need to be able to track the features much closer to the Sun.” The team have already started developing this system by modelling the path of the CIRs close to the Sun using ACE measurements, and comparing them with maps built up from HI images.

Bad space weather caused by high levels of solar activity can impact on power grids here on Earth. Image: K. Turnbull/J. Wild/ESA.

In a separate talk presented by Katie Turnbull on behalf of a team of scientists at Lancaster University and the British Geological Survey (BGS), the effect of geomagnetically induced currents (GICs) on UK power grids and how to predict them was discussed. The team have developed a new model using magnetic field measurements from all over the UK combined with a 3D model of how the ground beneath the UK conducts electricity.

The currents induced at over 250 locations in the high voltage national grid could then be estimated. Interestingly, the work not only showed that the induced current is dependent on the severity of the solar storm, but also on the configuration of the power grid. The model will be used to learn how the UK grid might respond to more damaging space weather events, such as that known as the Carrington flare of 1859, the most powerful solar storm in recorded history.

Capable of causing damage costing trillions of US dollars, understanding the interaction of the Sun with manmade technologies that we so heavily rely upon today is vital.

The Planets
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Hubble Reborn
Hubble Reborn takes the reader on a journey through the Universe with spectacular full-colour pictures of galaxies, nebulae, planets and stars as seen through Hubble's eyes, along the way telling the dramatic story of the space telescope, including interviews with key scientists and astronauts.

3D Universe
Witness the most awesome sights of the Universe as they were meant to be seen in this 100-page extravaganza of planets, galaxies and star-scapes, all in 3D!


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