Space weather

  • Space weather
    22.02.2011 11:19


    On 14/15 February the most significant “space weather” storm since 2007 hit the Earth, triggered by a powerful solar flare.

    The sun belched forth a series of coronal mass ejections (CMEs), sending billions upon billions of charged particles across space, causing aurorae to dance across the night sky in high latitudes a couple of days later as they hit the Earth’s magnetosphere, the region of space enclosing its magnetic field.

    Just a few communications were disrupted, notably across China. It could have been far worse because this was still a relatively minor storm in historical terms. In 1989, for example, a huge solar flare caused power failures across Quebec province, Canada. In 1859 an even stronger geomagnetic storm affected telegraph systems globally, even setting some of them ablaze.

    Given humanity’s increasing reliance on GPS, broadband and mobile communications a storm of similar magnitude might cause serious problems, even including the failure of satellites and of aircraft navigation systems.

    This latest flare is one of the signs of the sun awakening after a long period of abnormal quiescence. There is a cycle of approximately 11 years between solar maxima, although the next peak is expected to be delayed by about a year until 2013.

    Clearly, given the increased reliance on vulnerable technology since the last maximum in 2001, there is a need to monitor these bursts of energy, and they can be observed and forecast reasonably well. NASA and other agencies were able to issue warnings well in advance of the “Valentine’s Day Flare”, although mitigation is another matter.

    NASA is discovering more about these flares and how they interact with the Earth’s magnetosphere. In 2008 the agency launched the Interstellar Boundary Explorer (IBEX) satellite, which has been mapping the boundary between the solar system and interstellar space and imaging the heliosphere, the extent of the sun’s “atmosphere”.

    Closer to home, IBEX has also been looking at the magnetic tail (the “magnetotail”) that streams out behind the Earth, and specifically at something called the “plasma sheet”, where magnetic field lines part, come together and release energy.

    Parts of the sheet break off into “plasmoids” which shoot out into space while charged particles curve back towards Earth. IBEX has been able, for the first time, to create images of this region of the magnetosphere with cameras that detect energetic neutral atoms.

    Jim Slavin, a magnetotail researcher and Director of the Heliophysics Division at NASA’s Goddard Space Flight Center, says that “future NASA science missions may be able to make high definition videos of the development of space weather systems around the Earth to advance our scientific understanding of these phenomena and, eventually, enable space weather prediction like Earth weather prediction”.

    By: Stephen Davenport