A powerful geomagnetic storm that started Friday and lasted through Sunday caused the aurora borealis, also known as the northern lights, to be visible from much farther south than usual over the weekend, including in Central Oregon.

Observers reported seeing the phenomenon — usually appearing in the arctic and far northern longitudes — as far south as Florida and Oklahoma, due to the strength of the solar storm.

According to NASA, auroras are caused when energy and small particles from a solar storm travel down the magnetic field lines at the north and south poles into Earth’s atmosphere. There, the particles interact with atmospheric gases. Oxygen gives off green and red light. Nitrogen glows blue and purple, according to NASA. The lights at the south pole are called the aurora australis.

It wasn’t the first time the aurora has been visible in Oregon. According to the National Oceanic and Atmospheric Administration, the kind of “extreme G5” solar storm that occurred over the weekend happens an average of four times per 11-year cycle of the sun.