The strongest solar radiation storm to hit the Earth since 2005 is set to peak this morning.
The storm was triggered by a solar eruption on Sunday night with an M8.7 class flare, an earth-directed coronal mass ejection (CME), and a burst of fast-moving, highly energetic protons known as a solar energetic particle event.
Moving at nearly 1,400 miles per hour - faster-moving than most - the CME is expected to arrive at around 9.00 EST today, according to the National Oceanographic and Atmospheric Administration (NOAA).
Meanwhile, the amount of radiation reaching the Earth has been rising, reaching the S3 - strong - level, although it's expected to start declining soon.
There are concerns that the radiation could hit satellite communications, affecting astronauts on the International Sace Station and airplanes traveling over the poles, as well as GPS systems. Planes are likely to divert to lower latitudes as a result.
According to NASA, though, the physical safety of space station crew isn't at risk.
The CME - the plasma from the sun itself - is currently rated as G2, or moderate, although the NOAA warns that G3 levels are possible.
Its arrival may well intensify the appearance of the Northern Lights. Last night and the night before, sky watchers as far south as Ireland were treated to a dazzling auroral display.
Tonight, the NOAA is predicting that auroras could be seen in the US in New England, upstate New York and the Pacific Northwest.