WASHINGTON (AP) -- Space weather officials say the strongest solar storm in more than six years is bombarding Earth with radiation with more to come.The radiation is mostly an issue for satellite disruptions and astronauts in space. It can cause communication problems for polar-traveling airplanes.The Space Weather Prediction Center in Colorado observed the flare Sunday at 11 p.m. EST. Physicist Doug Biesecker says the biggest concern is the radiation, which arrived on Earth an hour later. It will likely continue through Wednesday.Biesecker said the storm's radiation levels are considered strong but other storms have been more severe. It is the strongest level since May 2005.Plasma ejected from the sun arrives Tuesday, but is not as strong. It can extend the visibility of auroras and disrupt the electrical grid.