Imagine an explosion on the far side of the Sun, so powerful that we can feel it here on Earth. It happened on July 13.
When space weather forecasters first saw this explosion, there was a moment of excitement. The impact from a flash of that magnitude could have been a real catastrophe for us. It seemed to be heading straight for Earth. But data from NASA’s STEREO-A spacecraft showed otherwise. In fact, the CME was headed directly away from us – an event on the far front.
Now for the best part:
Although the explosion occurred on the far side of the Sun, it still showered the Earth with high-energy particles. The Energetic and Relativistic Nuclei and Electrons Detector (ERNE) aboard SOHO recorded a burst of hard radiation shortly after the CME appeared.
How did this radiation reach our planet?
Rami Vainio, professor of space physics at the University of Turku, Finland, who works with ERNE data, says that “it is impossible to answer this question definitely without a detailed analysis involving several spacecraft.” However, she suggests that a global shockwave on the far side of the Sun may have been generated during the KVM takeoff. Particles overflowing over the edge could have spiraled toward our planet.
Of particular interest are the green data points in the graph above. These are the most energetic protons that ERNE can detect. The increase in green after the CME indicates unusually “hard” radiation, the kind that forms at the leading edge of a powerful CME.
The source of the explosion could be the same sunspot (AR2838) that produced the first X-burst of the 25th solar cycle on July 3. This sunspot is currently passing through the far side of the Sun at about the point where the CME came from.
AR2838 is expected to return within the next week – and then the real fun might begin…