Solar Flare Speeding Toward Earth, May Disrupt Power

The largest solar flare in five years is heading toward Earth and could disrupt power, radio communications, GPS and airlines, according to NASA. The flare was expected to hit Earth at 1:25 a.m. EST Thursday morning and last through Friday.

The sun erupted on Tuesday evening and sent two flares hurtling towards Earth at 4 million mph (6.5 million km/h).

It could give us a bit of a jolt, Alex Young, a NASA physicist, told The Associated Press.

Solar flares are intense bursts of radiation that come from the release of energy by the sun, according to NASA.

Flares can cause an increase in the electric current of the ionosphere, a part of Earth's atmosphere. Many communication systems, such as AM radio, bounce signals off of the ionosphere to reflect the signal over long distances. The increase in the electric current can disrupt the reflection.

Airlines rely on radio to communicate with ground control, which can be disrupted by solar flares. Flares also cause a change in the density of the ionosphere, causing GPS systems to become less precise.

Magnetic fields that accompany solar flares can cause a short in the electrical grid and knock out power. In March 1989, a solar flare caused 6 million people to lose power for nine hours, according to the AP.

While Thursday's solar storm has the potential to cause disruptions, scientists said the most likely effect will only be more noticeable auroras, also known as Northern Lights.

When solar flares hit Earth, the energy causes charged particles in the atmosphere to collide and release energy in the form of green, red or blue lights.

Usually seen best around the poles, Thursday's solar storm could create auroras as far south as the Great Lakes, according to The Associated Press. A full moon will make it difficult to see the lights, however.

The sun goes through periods of activity called the solar cycle. There are two periods, solar maximum and solar minimum, each measured by the number of sunspots. Solar flares usually occur in the presence of sunspots, according to NASA.

During solar maximum, there could be several hundred sunspots a day, according to NASA. Several days may pass without any sunspots during solar minimum. Each period lasts about 11 years.

The sun entered solar minimum in 2007.

The largest solar storm in recorded history occurred in September 1859. Numerous flares hit the Earth over two days, causing telegraphs all over the world to fail and auroras to be seen as far south as the Caribbean. The lights were so bright that the glow woke gold miners, who began cooking breakfast because they thought it was morning, according to National Geographic.