March 14, 2013
Sun Burps Up Two CMEs In Less That 12 Hours
Brett Smith for redOrbit.com - Your Universe Online
Earlier this week the sun twice ejected large amounts of solar material during two coronal mass ejections (CMEs) in a 12-hour period, according to a NASA report. The CMEs are not expected to significantly impact Earth.
The second CME began at 6:54 a.m. EDT on March 13, 2013. NASA scientists said that the ejection´s flank may pass by Earth at a speed that will not impact the planet. Faster moving CMEs can cause a shock wave, resulting in the disruption of radio signals.
Based on observations from the Solar Terrestrial Relations Observatory (STEREO) and the Solar and Heliospheric Observatory, NASA models indicate that both CMEs left the sun at around 400 miles per second, which is a normal speed for CMEs.
CMEs are often directed away from Earth, but those passing by our planet can cause a space weather phenomenon known as a geomagnetic storm. This occurs when the CME comes into contact with the magnetosphere, Earth´s magnetic field, for an extended period of time.
Historically, geomagnetic storms from CMEs of this kind are usually mild. They often go unnoticed by the public except for active auroras near the poles.
CMEs occur because of ℠kinks´ in the magnetic fields of the sun´s corona. This phenomenon, which often occurs above sunspots, can suddenly and violently release superheated gas and magnetic fields, or CMEs.
A large CME can contain a billion tons of matter and can reach speeds of up to several million miles per hour. The speed of a CME can be affected when it interacts with the solar wind, which can speed it up or slow it down. CMEs can be associated with solar flares, but can also occur independently, and scientists are currently unaware of any causal relationship between the two.
Besides threatening spacecraft, CMEs can also be harmful to astronauts, potentially exposing them to harmful cosmic radiation.
Solar activity has heightened over the past couple of years as the sun enters its solar maximum. The sun operates on an 11-year cycle, oscillating between periods of high and low activity. The solar maximum is a period of heightened activity and most experts said the current cycle will reach its peak in the fall of 2013.
During this period of heightened activity, scientists expect to see an uptick in intensity that should closely resemble the last solar maximum of 2002.
According to NASA, the space agency has “never been so well prepared for the onset of the next solar cycle.”
“NASA maintains a fleet of Heliophysics spacecraft to monitor the sun, geospace, and the space environment between the sun and the Earth,” said a statement on NASA´s official website.
The agency added that they hope to learn from this year´s activity so that they can better predict solar activity in the future.