ROCHESTER, N.Y. — If you were outside Friday night, you may have seen the blues, purples, and reds lighting up the sky. The aurora borealis was more visible in the Rochester area than it’s been in 20 years. 

But what exactly are the northern lights, and what makes them strong enough to be seen as far south as Rochester? News10NBC asked RMSC Director Jim Bader.

To know how we get to colorful night skies, we have to start 94 million miles away, on the surface of the sun. Like Earth, the sun has a magnetic field, and Bader explained that the field cycles through different levels of energy and activity every 11 years. 

While there’s always activity hitting Earth — called the solar wind — when the activity ramps up, it sometimes takes the form of a geomagnetic storm. 

“We have a scale of about one through five, and it gives us an idea of how severe [the geomagnetic storm] is,” Bader said. “At G1, it’s mostly quiet, you may see some northern lights. And then at G5, we’re really talking our most extreme storms.”

Friday, the National Oceanic and Atmospheric Administration rated the storm that passed Earth as a G5. While the storms usually get pulled to both poles by the earth’s magnetic field, a stronger storm will expand the light show further toward the equator. 

“It takes a lot for it to reach somewhere as far south as Western New York. Even though we are upstate, and we are very north for North America, it’s still pretty rare to reach us here,” Bader said. “For it to be on display and as easy as it was for us to see here – that is spectacular.”

Bader said the charged particles that make up a geomagnetic storm slam into our upper atmosphere. When they do, they interact with certain forms of oxygen and nitrogen, which is what gives us those waves of color.

“If you have the ability, if you have the opportunity to go out and view the northern lights — I cannot recommend it enough,” Bader said. “What a spectacular sight to see.”

Space weather is incredibly difficult to predict, so it’s hard to say exactly when a storm will hit Earth, or how strong it will be. First Alert Meteorologist Stacy Pensgen said another solar event has occurred on the sun, and scientists are waiting to see when it will make contact with Earth’s magnetic field, and how strong it will be.

While it’s unlikely to hit G5, and the storm may touch down during the daytime, Pensgen said the storm may be strong enough to bring yet another night of color to Western New York.