Tuesday, April 21, 2015

Active Regions Across the Front of the Sun Spotted by SDO, Geomagnetic Storms, CME Expected

Bright spots and illuminated arcs of solar material hovering in the sun's atmosphere highlight what's known as active regions on the sun, in this image from NASA's Solar Dynamics Observatory, captured on April 20, 2015. These are areas of intense and complex magnetic activity that can sometimes give rise to solar eruptions such as solar flares and coronal mass ejections. Credits: NASA/SDO

This solar image taken April 20, 2015, by NASA’s Solar Dynamics Observatory, or SDO, shows a complicated pattern of bright regions and soaring loops stretching across the front of the sun. These active regions have strong magnetic fields and appear as bright areas in extreme ultraviolet images. The twisted magnetic fields within the active region trap the hot, charged particles on the sun, called plasma -- making them hotter and often denser than surrounding areas. As the magnetic fields twist, they stretch and stress until they snap and reconnect into a simpler configuration. Sunspot AR2322 near the sun's western limb has unleashed four M-class solar flares in the past 12 hours alone, while a magnetic filament rose up on the sun's eastern limb, creating a magnificent prominence.Radio blackouts reaching the R1 levels were observed over the past 24 hours. The largest was at 11:57 UTC on Apr. 21. There is a slight chance for (R1-Minor) radio blackouts over the next three days as AR2322 rotates off the visible disk and the active region just beyond the East limb rotates on.

Satellite systems may experience significant charging resulting in increased risk to satellite systems.

Solar eruptions, such as flares and coronal mass ejections (CMEs), are often associated with active regions, although how and when a particular active region is to erupt is still an outstanding science question. Studying active regions as they rotate across the sun helps scientists understand more about what causes them to erupt.

“We know it is the interplay between the magnetic fields that trigger the flare, but we are still looking for a way to integrate our theory and observations to be able to predict exactly when an eruption will happen and how strong it will be,” said Michael Kirk, solar scientist at NASA's Goddard Space Flight Center in Greenbelt, Maryland.

National Oceanic and Atmospheric Administration (NOAA) forecasters estimate a 45% to 65% chance of polar geomagnetic storms during the next 12 to 36 hours. A solar wind stream and a CME are expected to hit Earth's magnetic field in quick succession, sparking G1-class disturbances on Apr. 21 and 22. Aurora may be visible at high latitudes such as Canada and Alaska.

Credit: NASANOAAspaceweather.com

No comments:

Post a Comment