In order to see the northern lights, one needs to travel to the extreme northern part of the planet. The aurora borealis is typically only visible in a band a few degrees of latitude wide, starting 10 to 20 degrees of latitude from the North Pole. Under normal circumstances, this means that only Alaska, northwest Canada, Greenland, Russia and the Scandinavian countries offer good viewing opportunities from land.
While the aurora is typically confined to a narrow band at extremely high latitude, solar activity can cause it to extend southward. When the sun emits a solar flare or coronal mass ejection, if any of the charged particles hit the Earth's magnetosphere, they can set off a geomagnetic storm. This ionization of the atmosphere can cause the northern and southern lights to both intensify and greatly expand. In many cases, the northern lights can extend into the continental United States, and extremely strong storms have made them visible as far south as Arkansas and Mississippi.
One of the most intense geomagnetic storms on record occurred in August 1859. Following a powerful solar flare, the northern lights filled the skies of much of the northern hemisphere with vivid, bright activity that illuminated cities almost like daylight. The energy storm was so intense that telegraph operators were able to disconnect their batteries and send messages using the natural energy flowing into the wires from the atmosphere.