A huge coronal mass ejection (CME) from the surface of the sun producing "machine gun flares" will mean the aurora could be visible this week in states like Iowa and Illinois. The hot cloud of plasma was launched from the sun on Sunday and is due to hit our atmosphere between August 17 and 19.

Coronal mass ejections (CMEs) release high-energy clouds of hot plasma from the surface of the sun, which then travel out into space. Most miss the Earth, but occasionally, one heads directly towards us.

As the CME cloud hits the Earth's atmosphere, electrons from the plasma are accelerated along the magnetic field lines towards the Earth's poles, where they collide with oxygen and nitrogen atoms and molecules in Earth's upper atmosphere. This excites the atoms to a higher energy state, after which they release their excess energy as the characteristic blue-green glow of the Northern and Southern Lights.

The stronger the geomagnetic storm, the further inwards from the poles the auroras can be seen.

The CMEs were launched from the Sun's surface on August 14 from a region of the sun known as AR3076. The mid-powered storms forecasted for this week are expected to occur as the CMEs hit our atmosphere in a "machine-gun fashion starting on the 18th," space weather physicist Dr. Tamitha Skov tweeted on Tuesday.

"Geomagnetic responses are likely to escalate to G3 (Strong) conditions on 18 Aug due to the arrival at or near Earth of multiple coronal mass ejections (CMEs) that have departed the Sun since 14 Aug," the U.S. National Oceanic and Atmospheric Administration's (NOAA) Space Weather Prediction Center (SWPC) said in a Tuesday statement.

The first in a succession of SIX #solarstorms is hitting Earth now! NASA/CCMC's Mary Aronne got this run spot on (see graphic). NOAA/SWPC has the other five hitting in machine-gun fashion starting on the 18th. Magnetic field is northward thus far but expect #aurora to build soon! pic.twitter.com/Q7i1nyuLY5

"Impacts to our technology from a G3 storm are usually minimal. However, a G3 storm has the potential to drive the aurora further away from its normal polar residence, and if other factors come together, the aurora might be seen over portions of Pennsylvania, Iowa, to northern Oregon," the NOAA said.

The lights are usually strongest between 9 p.m. and 2 a.m., and the best sightings often occur between 11 p.m. and midnight, according to the travel website Discover The World.

Additionally, according to the NOAA map of the reach of G3 storms, the aurora may be visible from small parts of northern Idaho, Oregon, Wyoming, Iowa, Illinois and Pennsylvania.

Geomagnetic storms are classed on a scale of one through five, with a G1 storm being the weakest and a G5 being the most powerful. While G1 storms are very common, more powerful storms are much rarer.

"[G1 storms] don't have any serious effects. G5 storms can have serious effects. But we haven't had a G5 since October 2003," Mike Hapgood, a Principal Consultant on Space Weather at STFC Rutherford Appleton Laboratory, previously told Newsweek.

The aurora will appear in the sky as slowly rippling curtains of an eerie green-blue light spanning the whole sky. The further south observers are, the closer to the horizon the aurora will appear.

To take the best photos of the aurora, longer exposure times allow the camera to take in as much light as possible, bringing out maximum details and color.

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