On Sept. 24, the National Oceanic and Atmospheric Administration’s (NOAA) Space Weather Prediction Center issued a warning for a strong, level G3 geomagnetic storm on Earth from an explosion of the sun’s corona. This caused a shock to Earth’s magnetic field which can at times cause extreme weather known as ÛÏgeomagnetic storming.Û.
The sun experienced a coronal mass ejection in which it expelled particles at 5 million miles per hour. Luckily, this was not aimed directly at Earth, which prevented a shift to extreme weather. However, the area on the sun that caused this to occur is still active, so we can expect to see another coronal mass ejection in the near future. NOAA is monitoring this closely.
Coronal mass ejections are balloon-shaped bursts of solar wind that rise above the solar corona while expanding. Super-heated electrons then begin to move faster than the solar wind along magnetic field lines, which causes solar flares. These flares eject particles at great speeds, some having the power of one billion hydrogen bombs.
Coronal mass ejections are most common at the end of the 11-year solar cycle. The last cycle ended in 2001, so we can expect more solar activity during the next year. The term for disturbances in the Earth’s magnetosphere caused by Sun ejections is space weather. Space weather is caused by changes in the sun’s plasma and energetic particle populations.
The largest storms are caused by coronal mass ejections that can have lasting effects on long-term climate patterns. Other disruptions include: Electrical current surges in power lines; interference in the broadcast of radio, television, and telephone signals; strange behavior in air and marine navigation instruments and compasses; pipeline corrosion, and problems with defense communications. Space weather also can change the atmospheric ozone layer. NOAA and other agencies monitor the sun’s activities closely to prevent damage to electrical grids and radio and satellite telecommunications on Earth.
Monitoring solar activity is especially important for astronauts aboard the International Space Station. In the case of heavy solar flares, NASA must observe exposed radiation levelsclosely. In a 2003 statement, Mike Golightly, manager of the Space Radiation Analysis Group at NASA’s Johnson Space Center, said, ÛÏTo date the recent eruptions, or coronal mass ejections, have not resulted in any additional radiation exposure to the crew, nor is any increase expected from these events.Û
Solar flares also can produce effects such as the aurora borealis and the aurora australis. These are the northern and southern lights most common at the end of the 11-year solar cycle. They are potent geomagnetic storms caused by solar flares, similar to coronal mass ejections. The last occurrence of these lights was on Sept. 26, 2011.
To better study these geomagnetic storms, NASA launched a fleet of five spacecrafts in 2007 in a project called THEMIS (Time History of Events and Macroscale Interactions during Substorms). One particular storm that these satellites observed crossed an entire polar time zone in 60 seconds. Dave Sibeck, project scientist at NASA GSFC, said in a Geology.com article, ÛÏThese satellites have detected magnetic Û÷ropes’ connecting Earth’s upper atmosphere directly to the sun. We believe that solar wind particles flow in among these ropes, providing energy for geomagnetic storms and auroras.Û