Stormy, with a chance of X-rays

Illustration by Philippe Intraligi
Date:1 July 2010 Tags:

The sun gives the Earth life, but it also poses a planetary threat. X-ray bursts and magnetically driven explosions of solar material can wreak havoc by knocking out satellites, causing power failures and emitting radiation surges that require airline flights to be rerouted. To keep an eye on our local star, this year Nasa launched the Solar Dynamics Observatory (SDO) satellite. “Imagine a weather system where instead of the water cycle, with rain and snow, it has magnetic fields,” SDO project scientist Dean Pesnell says. The five-year, R6,4 billion mission continually beams data to Earth at 150 megabits per second. The information will be used as a warning system and to better predict damages.

Solar dynamics observatory sensors

Helioseismic and magnetic imager (HMI)
Currents of plasma and other material beneath the surface create magnetic elds that generate solar emissions. HMI uses seismic data to map the strength of these elds and forecast eruptions.

Atmospheric imaging assembly (AIA)
AIA takes images of the Sun’s atmosphere and filters them at 10 different wavelengths. These images are combined with data from terrestrial and space instruments to document changes inside the Sun before, during and after spouts of solar material.

Extreme ultraviolet variability experiment (EVE)
EVE measures changes in the Sun’s output of extreme ultraviolet radiation, which in­ uences the amount of protective ozone enveloping the Earth. Ultraviolet surges can also shatter molecules in the atmosphere, forming ions that disturb radio signals.

In history

1859 Astronomers observe the strongest solar storm ever recorded.

1921 New York City trains are disabled by a solar ejection.

1940 A space storm disrupts radio signals and stops US long-distance phone service.

1989 A coronal ejection knocks out power to 6 million Canadians.

1997 A solar ejection disables a R1,5 billion AT&T satellite.

2003 The biggest recorded X-ray flare damages 28 satellites.

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