Space station astronauts and airlines are bracing for a solar storm that could also impact communications and GPS accuracy.
Forecasters at the NOAA Space Weather Prediction Center say a strong geomagnetic storm pulse is likely to reach the Earth on Thursday and Friday.
The pulse comes from a sunspot eruption that was monitored at 12:32 p.m. CT on Tuesday.
"Solar flares can disrupt power grids, interfere with high-frequency airline and military communications, disrupt Global Positioning System (GPS) signals, interrupt civilian communications, and blanket the Earth’s upper atmosphere with hazardous radiation," NOAA said in a written statement.
An unmanned resupply cargo rocket that was to have been launched to the International Space Station on Wednesday was postponed until at least Thursday because of the potential radiation danger.
The sun is at the peak of a weak 11-year storm cycle.
Some passenger jets were being diverted from the poles to avoid potential communication and health issues as the intensity of the solar storm was increased from "moderate" to "strong." GPS devices also were at risk.
But the six men aboard the space station were safe from the solar fallout, NASA said, and satellites also faced no threat. The Cygnus cargo ship aboard the rocket, for example, is built to withstand radiation from solar flare-ups.
The storm also will push the colorful northern lights farther south than usual to the northern U.S. Parts of Colorado, Kansas and Missouri may be treated to a rare glimpse of the phenomenon.