The shortest day is about an hour longer in Juneau, almost 2 hours shorter in Fairbanks. In the parts of Alaska where the sun still rises and sets, its journey through the day describes an arc through the heavens in the southern sky. If you're moving to Alaska, be sure to get a home with south facing windows. Painters have fallen in love with the unusual winter light that often gives the snowclad mountains and landscape a pinkish cast. The Northern Lights are one of the least predictable winter attractions in Alaska.
Folks try though.
The weather page of the Anchorage Daily News includes a Northern Lights forecast and the Geophysical Center at the University of Alaska Fairbanks has put its Northern Light forecasts online. They're rarely seen from Anchorage though, because of the brightness of the city lights. Viewing is better away from the city.