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Solar blast heads for Earth
Posted: 03 August 2010

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The Sun appears to have jolted from its deep slumber, blasting tonnes of plasma into interplanetary space on Sunday, which is expected to collide with the Earth within the next 24 hours.

“This eruption is directed right at us, and is expected to get here early in the day on 4 August,” says astronomer Leon Golub of the Harvard-Smithsonian Center for Astrophysics. “It’s the first major Earth-directed eruption in quite some time.”

This movie of the magnetic filament breaking away from the Sun's surface was recorded by the extreme ultraviolet cameras onboard the Solar Dynamics Observatory. Credit: SDO (NASA).

NASA's new Solar Dynamics Observatory, along with other solar satellites, had front row seats for the action, spotting a parade of activity from flares to filaments of magnetism lifting off the solar surface, to shaking of the solar corona and a coronal mass ejection (CME). The flare appeared to emanate from sunspot 1092, but at the same time, 400,000 kilometres away, an enormous magnetic filament seemed to rise from the surface. The timing of the events suggests they are connected; a solar tsunami rippling across the northern hemisphere of the Sun likely helped propel the filament into space, where part of it broke away and is now racing across the 150 million kilometres of interplanetary space towards Earth.

When this mass of plasma arrives at the Earth it will buffet against our planet's magnetic field. If the magnetic field conditions at Earth are right then solar particles will stream down the field lies to interact with nitrogen and oxygen atoms in the upper atmosphere, producing spectacular curtains of green and red light known as auroral displays. Observers in northern latitudes should look north this evening and in the early hours of tomorrow morning to try and catch a glimpse of these beautiful natural displays.

Occasionally, geomagnetic storms can wipe out Earth-orbiting communication satellites and ground based power grids, but fortunately this storm is not likely to pose such a threat. The flare rated C3 on the solar flare classification scale, which is the weakest breed of flare; for comparison, M-class flares cause brief, localised radio blackouts while deadly X-class flares can trigger global disruption.

This sudden burst of activity could herald the onset of a period of increased activity that will lead the Sun to solar maximum. The Sun goes through a regular 11-year cycle of activity, with the last solar maximum peaking in 2001.

Read our updated story, Get ready for a second blast, here.