HOUSTON — A medium-sized solar flare is hurtling toward Earth, set to arrive Sunday with intense solar particles of ionizing radiation lasting through Monday. This sounds scary, but Houston won’t feel much from this event. There will be no danger on the ground. For areas north of 55°N latitude, which includes much of Canada, Alaska, northern Europe and Russia, there could be interference in the shortwave radio bands affecting communications with commercial pilots flying over the north pole, en route to Asia from America and vice versa. In some cases, airlines can delay or cancel flights, fearing extended radio blackouts over desolate arctic terrain. (Imagine if there was an emergency and the pilot couldn’t radio for help?) Amateur radio operators (ham) using “intercontinental”, 10 meter or lower HF frequencies could experience propagation issues, greatly reducing their over-the-horizon reach.