Intense solar activity this year means people across Maine will have plenty of opportunity to check out the northern lights. The Space Weather Prediction Center at the National Oceanic and Atmospheric Administration has issued a forecast that suggests the aurora borealis may be seen this week across parts of Maine. The forecasts are subject to change sometimes on very short notice, and whether you can see them where you are depends on cloud cover and how bright the moon might be. Here is what we know for Sept. 13.