The US weather service has warned of an unusually intense solar flare which could disrupt satellites and electricity grids. Deutsche Welle takes a look at what a solar storm is and the damage it can do.
Scientists say solar activity peaks every 11 years
It was expected that satellite navigation devices and radios would experience waves of interference on Wednesday, the US National Weather Service (NWS) said, as a massive solar flare erupted on the sun.
The solar storm was also expected to affect power supplies and could cause malfunctions in other electrical systems. Furthermore, flights through polar regions may need to be diverted, the NWS warned.
The so-called Coronal Mass Ejection is a huge burst of solar wind and magnetic fields from the sun which are released into space. Klaus Börger from the Geo Information Service with Germany's armed forces, the Bundeswehr, said such eruptions can develop from sunspots which are visible from Earth.
US space agency NASA said it observed the recent solar activity from 12 unmanned satellite observatories and spacecraft using a specialized telescope for measuring radiation which was installed in a lunar probe and launched in 2009.
Satellites are particularly affected by solar storms
Nuclear fusion reactor
The sun has a diameter of just under 1,400,000 kilometers (roughly 865,000 miles) with an internal temperature of several thousand degrees Celsius. This heat is produced by nuclear fusion which creates millions of tons of hydrogen and helium by the second. These nuclear reactions lead to observable explosions.
Recent days have seen several small outbreaks, culminating in three different types of radiation exposure. Immediately following an explosion, a flash of light sparks out from the sun, taking little over eight minutes to travel the 150 million kilometers to Earth. Around 30 minutes later, charged particles loaded with a voltage in the billions begin striking the Earth's atmosphere. Next comes the actual geomagnetic storm, which consists of particles racing toward the Earth at roughly 900 km/s. They need up to 46 hours to reach our planet.
NASA scientists have classified the current eruption as major and warned it could lead to ongoing radiation storms. The NWS, meanwhile, said it anticipated the effects of the storm would be "low to moderate," given Earth was not directly in the path of the eruption.
According to NASA, this is the most violent solar storm since 2006. The most powerful solar event on record occurred in 1859. Experts warn that if a similar "super eruption" were to take place today it could knock out infrastructure across large swathes of the world.
Scientists have been studying Coronal Mass Ejections for decades
Solar storms are considered a threat to key infrastructure due to our dependency on technology such as satellites, which are particularly sensitive to changes in surrounding electromagnetic fields. Satellite-controlled GPS navigation systems are now an indispensible element of the logistics sector, as well as important for the maritime and aviation industries. They are particularly vulnerable to solar activity.
Satellites send their electromagnetic signals from around 20,000 km above Earth, said Klaus Börger: "At an altitude of between 1,000 and 50 km [the signals] then travel through the ionosphere, and this influences the direction and speed of the signal."
GPS receivers determine their position from signals obtained from at least four satellites. "The signal travel time is multiplied with the speed of light to calculate the distance to the satellite," said Börger.
However, distortions to the electromagnetic field in the ionosphere can change the signal travel time. "This can mean GPS failures depending on dramatic deviations in the ionosphere," Börger said.
Electrical systems are also heavily impacted by solar radiation, as evidenced nearly 40 years ago, long before the Internet and GPS age. In 1973, a solar flare caused a blackout in the Canadian province of Quebec, leaving six million people sitting in the dark. The power interruption was caused by a deformation of the Earth's magnetic field by incoming charged particles.
The aurora borealis lights are visible in the northern reaches of the world
Magnetic fields generated through solar storms which correspond with electrical fields and currents on Earth can also have other effects, said Börger, including even burning out transformer substations.
NASA scientists already know that solar activity follows certain cycles which reach a high point approximately every 11 years. The next apex is expected to come around in 2013. During periods of high sunspot activity, people with shortwave radios will be able to detect reception disruptions.
Earth's magnetic field protects us from cosmic radiation carried by incoming particles in the event of such solar high points. A side effect of this can be seen at the Earth's poles in the aurora borealis and australis, or northern and southern lights. The colorful lights in the sky are caused by the collision of charged particles caused by a solar wind and directed by the Earth's magnetic field.
Author: Fabian Schmidt (AFP, AP) / dfm
Editor: Nicole Goebel