Will you be watching for the Northern Lights? Share your photos with CNN iReport

(CNN) Youvathana Sok looked up and saw more than just stars in the crisp, clear Maine night sky.

A colorful, spectacular showing of the aurora borealis greeted Sok, a CNN iReporter, and others at Cadillac Mountain in Acadia National park on Friday.

Greens and whites lit up the night sky, treating viewers to a once-in-a-lifetime showing.

Thanks to a relatively strong solar storm, those living in northern parts of the United States had a chance to take in the vivid colors that normally can only be seen from extremely high latitudes.

Experts say the combined energy from two recent solar events has arrived, prompting the Space Weather Prediction Center to issue a strong geomagnetic storm watch for Saturday.

Wait. What's a solar storm? Basically, the sun is a giant ball of gas : 92.1% hydrogen and 7.8% helium. Every now and then, it spits out a giant burst of gas that contains magnetic properties called a coronal mass ejection.

These ejections are sometimes associated with solar flares, the most explosive events in the solar system. The sun has released two ejections in the past few days, and both are linked to solar flares. NASA says the second flare is an X1.6 class, putting it in the most intense category

The energy from those two ejections is now hitting Earth. Space weather experts aren't sure what this solar storm will do.

Photos: Space weather: Fine, with a chance of solar flares Photos: Space weather: Fine, with a chance of solar flares Researchers studied the major solar flare that occurred October 24, 2014, to develop a better model for understanding and predicting solar eruptions. Hide Caption 1 of 13 Photos: Space weather: Fine, with a chance of solar flares A midlevel flare erupted on the left side of the sun on July 8, 2014. This image from NASA's Solar Dynamics Observatory highlights the high-temperature solar material in a flare, which is typically colorized in teal. Hide Caption 2 of 13 Photos: Space weather: Fine, with a chance of solar flares NASA's Solar Dynamics Observatory, which observes the sun 24 hours a day, captured this image of a solar flare on June 10, 2014. Hide Caption 3 of 13 Photos: Space weather: Fine, with a chance of solar flares NASA captured this second flare, which appears as a bright flash on the left side of the sun, on June 10, 2014. Hide Caption 4 of 13 Photos: Space weather: Fine, with a chance of solar flares A coronal hole, almost square in its shape, is one of the most noticeable features on the sun on May 5-7, 2014. A coronal hole is an area where high-speed solar wind streams into space. It appears dark in extreme ultraviolet light as there is less material to emit in these wavelengths. Inside the coronal hole, you can see bright loops where the hot plasma outlines little pieces of the solar magnetic field sticking above the surface. Because it is positioned so far south on the sun, there is less chance that the solar wind stream will impact us here on Earth. Hide Caption 5 of 13 Photos: Space weather: Fine, with a chance of solar flares A large active region is giving off warning signs that this could be the source of powerful solar storms. It shot off two smaller flares (January 2, 2014) as shown here in a wavelength of extreme ultraviolet light. Hide Caption 6 of 13 Photos: Space weather: Fine, with a chance of solar flares This image from the Solar Dynamics Observatory shows the sun on July 12, 2012, during an X1.4 class flare. The image is captured in the 304 Angstrom wavelength, which is typically colorized in red. Hide Caption 7 of 13 Photos: Space weather: Fine, with a chance of solar flares This image combines two sets of observations of the sun on July 12, 2012, from the Solar Dynamics Observatory to give an impression of what the sun looked like shortly before it unleashed an X-class flare. Hide Caption 8 of 13 Photos: Space weather: Fine, with a chance of solar flares A very large filament became unstable and erupted June 27, 2012, as seen by the STEREO Ahead spacecraft in a wavelength of extreme UV light. Hide Caption 9 of 13 Photos: Space weather: Fine, with a chance of solar flares Active Region 1514 just could not contain itself as it popped off over a dozen flashes, minor eruptions and flares over almost two days June 27-29, 2012. Hide Caption 10 of 13 Photos: Space weather: Fine, with a chance of solar flares Two areas of dark plasma that were close together danced and entwined with each other over March 27-28, 2012. The dark plasma, seen in profile, was somewhat cooler and therefore darker than the material around it. Hide Caption 11 of 13 Photos: Space weather: Fine, with a chance of solar flares This close-up view of a prominence reveals magnetic forces at work as they pull plasma strands this way and that before it gradually breaks away from the sun over November 14-15, 2011. Hide Caption 12 of 13 Photos: Space weather: Fine, with a chance of solar flares Sunspots, which are cooler, darker areas of intense magnetic activity, are most often the source of solar storms. Here, observations of the sun's lower atmosphere in extreme ultraviolet light July 17-18, 2011. Hide Caption 13 of 13

Earth's atmosphere usually protects us humans, but you might want to keep a flashlight handy. Solar storms can knock out power, interfere with GPS and radio communications -- including those on commercial airliners -- and damage satellites.

"People on the ground really don't have to worry," said Lika Guhathakurta, a program scientist with NASA's Solar Dynamics Observatory. She said solar storms don't affect humans on the ground, although astronauts could be at risk.

And our technology.

But don't worry too much. NASA can take steps to protect the crew members on the International Space Station, and satellite operators can turn off sensitive sensors on satellites.

Should we be worried the solar storm will fry our smartphones or other gadgets? "No, very unlikely," Dr. Petrus Martens, an expert on solar flares and a professor in the Department of Physics and Astronomy at Georgia State University, told CNN. "Of course if we lose the (power) grid, that will eventually affect cell phones and the Internet as well."

Besides power grids and satellites, Martens says other possible impacts are:

• Distortions in GPS readings of up to a few yards. That is not much, but it can be crucial for military applications; for example, targeting by drones.

• Increased corrosion of long pipelines like the Alaska oil pipeline.

• Homing pigeons going off course. (Martens is not joking about that one.)

Solar storms have caused havoc on Earth before. On March 13, 1989, a solar storm knocked out power for the entire province of Quebec for 12 hours. Power grids in the United States were affected but didn't have blackouts. NASA says some satellites tumbled out of control for hours during what's known as the Quebec Blackout. The space shuttle Discovery was in orbit at the time and had a mysterious sensor problem that went away after the storm, NASA says.

On the upside, solar storms also create beautiful aurora. Aurora watchers in the northern United States who are outside major metropolitan areas should be watching the skies the next few nights.

"A fantastic display of Northern Lights as far south as the northern half of the U.S." is possible, Martens said.