A wild week of space weather
Posted January 30, 2012
The sun was very active last week, releasing numerous solar flares and prompting action worldwide. One of those flares produced a coronal mass ejection (CME) containing up to a billion tons of plasma prompting to warnings from space weather forecasters.
Our ability to predict when these effects will be felt has significantly improved with spacecraft in Earth and solar orbit as well as ground based observations. NOAA's Space Weather Prediction Center in Boulder, Colorado puts out watches and warnings not unlike the National Weather Service does for terrestrial weather. Unlike sunlight which takes a little over 8 minutes to travel the 92 million miles to Earth, CMEs and effects from flares are travel more slowly giving forecasters more time to issue warnings.
Solar activity is monitored from NASA’s Goddard Space Weather Center outside Washington D.C. where images and data from the Solar Dynamic Observatory (SDO), Solar & Heliospheric Observatory (SOHO), and STEREO spacecraft. The later is a pair of spacecraft allowing researchers to view nearly the entire surface of the sun and even construct 3D images for study.
Sunspots, the relatively cool spots created by magnetic activity on the sun choking off the flow of heat, are tracked for flare eruptions as they move around the sun's surface. Activity is also tracked in the corona, the part of the sun which extends out hundreds of thousands of miles. If you've seen a total solar eclipse, the corona the glow that is visible when the moon slides in front of the sun's disk.
Here in Raleigh we are protected by from this solar activity by a magnetic field. That field wraps Earth like a doughnut leaving the northern and southern poles more exposed. The spectacular green and blue swirling hues you may have seen in aurora photos last week from Canada, Sweden, or New Zealand were made possible by charged particles which made their way into the upper atmosphere through the top and bottom of that doughnut. The stronger the magnetic storm the sun sends our way, the less protection that doughnut offers and the further south those aurae can be viewed. Recent auroral activity has been seen as far south as Virginia.
Space weather isn't all pretty light shows. Astronauts living aboard the International Space Station must take shelter in more shielded parts of the station to wait out storms. CMEs and flares can disrupt high frequency communications used by aircraft and ships. Last week Delta and other airlines rerouted flights that would normally fly over the pole to avoid this. Avoiding the polar routes during these times also reduces radiation exposure for passengers and flight crew. Power companies are particularly interested in predictions to give them time to respond to the extra current injected into the power grid by these storms avoiding transformer overloads which can cause outages.
Remember to never look directly at the sun, especially with a non-solar telescope. You can safely see whats going on right now with our sun by visiting http://spaceweather.com or http://www.swpc.noaa.gov/SWN.
Tony Rice is a volunteer in the NASA/JPL Solar System Ambassador program and software engineer at Cisco Systems. You can follow him on twitter @rtphokie.