PITTSBURGH (KDKA) – The Northern Lights may be visible in Western Pennsylvania on Friday.

First Alert meteorologist Ray Petelin says it’s possible, but not guaranteed. The Pittsburgh area should generally be close to an 8 on the K-index, which measures the size of geomagnetic storms. On Friday we will be around 6 or 7, he says.

There was a chance that the Northern Lights would be visible on Thursday, but the chance is even greater for Friday. The K-index will probably be too weak to see them on Saturday.

If the Northern Lights are visible in Western Pennsylvania, look for a dark spot on the northern horizon. It is recommended that you give your eyes some time to adjust to the darkness.

The Northern Lights have already graced the Pittsburgh area a few times this year. Both the Northern Lights and the Perseid meteor shower were visible one evening in August, providing a dazzling celestial show. Green, purple, red and pink shades were also visible in the skies of western Pennsylvania back in May.

What causes the Northern Lights?

When a geomagnetic storm occurs, solar wind is sent towards Earth. Charged protons and electrons follow the Earth’s magnetic field and enter the Earth where the magnetic fields are weakest: the poles. The electrons collide with all the different molecules that make up our atmosphere, creating a dazzling display of colors in the sky.

It is rare for the Northern Lights to be seen so clearly this far south. Usually we’re lucky if it only happens once a year.