This flare, a wave of particles moving at near the speed of light, arrives at Earth shortly after the light itself, which takes about eight minutes to cross the 93 million miles. In other words, sky-watchers won’t know there has been a solar flare until shortly before the radiation arrives.
The burst is largely cushioned by Earth’s atmosphere, according to Madhulika Guhathakurta, program director for the National Aeronautics and Space Administration’s STEREO mission, which studies solar forces from a pair of spacecraft orbiting the sun.
Because of atmospheric padding, the burst poses little risk to people on the ground. However, airplanes at cruising altitude and spacecraft are much more vulnerable. The flash also can zap electronics on satellites, which lie entirely outside the safety of Earth’s atmosphere.
While this initial burst can be dangerous, there’s a much slower wave of energy – a coronal mass ejection (CME) – that really can mess with electronics.
Not every flare produces a CME, and they often occur when no flare is present. When they do spew out, CMEs send strong waves of electromagnetic force our way. The most visible signs of this are the colorful northern and southern lights. But it also has more serious consequences.
For one, it can cause electrical transformers to trip or fail, which can lead to widespread power outages. A particularly powerful CME storm hit Earth in 1921, before electricity played as big a role in daily life. If a burst of similar magnitude hit today, it would interrupt power for as many as 130 million people, according to a recent report by the National Academy of Sciences. In 1989, a geomagnetic storm knocked out power to 6 million people in Quebec.