December 7, 2013
Sun’s Magnetic Solar Cycle Depicted In New NASA Visualization
[ Watch the Video: The Sun's Changing Magnetic Field ]
redOrbit Staff & Wire Reports - Your Universe Online
According to Karen C. Fox of the Goddard Space Flight Center, the magenta colored lines represent regions where the overall field is negative, while the green lines represent areas that are positive and the gray lines represent areas of local magnetic variation.
[ Watch the Video: The Sun Reverses its Magnetic Poles ]
“The entire sun's magnetic polarity, flips approximately every 11 years – though sometimes it takes quite a bit longer – and defines what's known as the solar cycle,” Fox wrote on Friday. “The visualization shows how in 1997, the sun shows the positive polarity on the top, and the negative polarity on the bottom.”
Over the course of the next 12 years, however, positive and negative lines can be seen moving slowly towards the opposite pole, ultimately culminating in a complete flip of the magnetic poles. During the peak of each magnetic flip, Fox added, the sun experiences periods of increased solar activity, resulting in additional sunspots and events such as solar flares and coronal mass ejections (CMEs).
NASA released a movie in August, preparing astronomy aficionados for what is known as the solar maximum magnetic flip. In that video, the US space agency revealed that data collected from observatories predicted the event would occur in about three to four months, and the effects would be felt throughout the solar system.
“A reversal of the sun's magnetic field is, literally, a big event. The domain of the sun's magnetic influence (also known as the ‘heliosphere’) extends billions of kilometers beyond Pluto. Changes to the field's polarity ripple all the way out to the Voyager probes, on the doorstep of interstellar space,” NASA’s Tony Phillips explained.
During solar field reversals, the current sheet – a surface protruding outward from the sun’s equator where the magnetic field induces an electrical current – becomes wavy. While the current itself is just one ten-billionth of an amp per square meter, the amperage flows through a region 10,000 kilometers thick and billions of kilometers wide. Disruptions in the current sheet can lead to stormy space weather surrounding Earth.
“Cosmic rays are also affected. These are high-energy particles accelerated to nearly light speed by supernova explosions and other violent events in the galaxy,” Phillips said. “Cosmic rays are a danger to astronauts and space probes, and some researchers say they might affect the cloudiness and climate of Earth. The current sheet acts as a barrier to cosmic rays, deflecting them as they attempt to penetrate the inner solar system. A wavy, crinkly sheet acts as a better shield against these energetic particles from deep space.”
Image 2 (below): An artist's concept of the heliospheric current sheet, which becomes more wavy when the sun's magnetic field flips. Credit: NASA