A magnetic storm could light up the sky this weekend over a broad stretch of the northern United States, according to researchers at the federal Space Weather Prediction Center.

With clear skies forecast and a “coronal mass ejection” set to arrive Saturday, an aurora could be visible as far south as Chicago, according to prediction center estimates.

The light of the moon could making viewing difficult, however, as the moon was full on Wednesday and will rise in the eastern sky at about 10:50 p.m. Saturday night.

The Northern Lights, if visible, will be in the northern sky and are best viewed away from light on the ground.