Several states may see northern lights this weekend: When and where could aurora appear?

The sun has had a busy week.

The first few days of October have seen plenty of solar activity with two observed coronal mass ejections, including the massive X7.1 solar flare on Tuesday, and then a rare X9 solar flare on Thursday, according to the National Oceanic and Atmospheric Administration's Space Weather Prediction Center.

Solar flares are sudden eruptions of energy that occur on the sun's surface and can trigger aurora sightings here on Earth.

This means the coming weekend could bring the chance for many Americans to potentially see the northern lights ? the colorful phenomena known as aurora borealis ? in the skies on Friday and Saturday evenings.

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Northern lights may peak Saturday evening

As of Friday afternoon, the National Oceanographic and Atmospheric Administration's Space Weather Prediction Center predicts a "mild-strong" geomagnetic storm from Oct. 4-6, with activity peaking on late Saturday evening heading into Sunday.

The center said outside variables could impact the reliability of the forecast including the precise trajectory of the solar eruption, which can change during its 93 million mile journey to Earth.

"This forecast comes with a fair amount of uncertainty because initial space weather predictions rely on remote and limited solar observations," the center said in a statement to USA TODAY Wednesday. "Auroras can be unpredictable, waxing and waning quickly. Visibility might range from bright and relatively high in the sky to faint and low on the Northern Horizon (maybe only visible with long-exposure camera shots), or even not visible at all."

On Friday, the center anticipates that the northern lights will be visible, assuming clear weather conditions, near the Canadian border. On Saturday, the phenomenon may be visible as far south as Oregon, Nebraska, Illinois and Pennsylvania. As of Friday, weather models showed that large portions of the United States are forecast to have clear skies Saturday evening.

Why are the northern lights more frequent?

As auroras form, Earth's magnetic field redirects the particles toward the poles through a process that produces a stunning display of rays, spirals and flickers that has fascinated humans for millennia. Whether hues of green, red, blue and pink dance about in the sky is due to the altitude in which the collisions occur, as well as the composition and density of the atmosphere at the time.

By then sunspots located in regions of intense magnetic activity should increase, according to the NOAA. When that magnetic activity is released, it creates intense bursts of radiation resulting in solar flares – considered by NASA to be our solar system's largest explosive events.

Solar flares emit radiation commonly in the form of ultraviolet light and X-rays that can hurtle toward Earth at the speed of light. Some of these flares can be accompanied by coronal mass ejections, or clouds of plasma and charged particles, that emerge from the sun's outermost atmosphere, the corona.

These ejections can collide with Earth’s magnetosphere, the barrier protecting humanity from the harshest impacts of space weather, to produce geomagnetic storms.

As auroras form, Earth's magnetic field redirects the particles toward the poles through a process that produces a stunning display of rays, spirals and flickers that has fascinated humans for millennia. Whether hues of green, red, blue and pink dance about in the sky is due to the altitude in which the collisions occur, as well as the composition and density of the atmosphere at the time.

Eric Lagatta and Anthony Robledo Jr. contributed to this report.

Max Hauptman is a Trending Reporter for USA TODAY. He can be reached at [email protected]

This article originally appeared on USA TODAY: Northern lights could be visible tonight, this weekend: When and where