Yesterday morning, the sun unleashed a massive flare, its most powerful in nearly five years.
At 3:48 am EDT, it blasted out an X6.9 flare, aimed at the Earth. According to NASA, it's big enough to potentially cause some radio communication blackouts.
It's also produced an increase in solar energetic proton radiation - enough to affect humans in space if they don't protect themselves.
There have already been some reports of disruption to VLF and HF radio systems in Asia.
The effects could have been greater. There was also a coronal mass ejection (CME) associated with the flare - which sends solar particles into space and can affect electronic systems in satellites and on Earth. However, the CME isn't traveling toward Earth on this occasion.
The flare is the largest yet during the sun's current 11-year cycle, expected to last until around 2020. Over the next three to five years, we can expect to see more similar events.
"This flare had a GOES X-ray magnitude of X6.9, meaning it was more than 3 times larger than the previous largest flare of this solar cycle — the X2.2 that occurred on Feb 15, 2011," says NASA's Solar Dynamics Observatory.
According to the NOAA's Space Weather Prediction Center, though, we're now in for a quiet few days. Over the next three days, it says, solar activity is likely to be low to moderate, decreasing as Region 1263 - the source of the flare - rotates away from us.