Two blasts of energy from the sun hit the Earth's magnetic field Friday and could disrupt one or more electrical grids, global-positioning systems or other satellite-communications systems, scientists at the National Oceanic and Atmospheric Administration said Friday.

The blasts touched Earth's magnetic field in the form of fast-moving "solar wind" and is blowing by the Earth, Joseph Kunches, a space weather scientist with NOAA's Space Weather Prediction Center, said in an interview.

Mr....