Auroras Off the Page
Did our February 2013 cover story inspire you to become an aurora hunter? The Internet provides several sources for aurora forecasting. Combined with weather predictions, these forecasts are a useful tool for both hardcore hunters and curious tourists.
The Kjell Henriksen Observatory on Svalbard actively tracks the auroral oval and has maps available both online and through its smartphone app, which works on all platforms and is available for download through Windows Marketplace, the iTunes Store, and Google Play. You can check if the northern lights are visible where you live at any time using either method.
There are also several useful webpages, among them:
- The KHO UNIS forecaster, which indicates where the aurora oval is located right now: kho.unis.no/Forecast.htm
- The KHO mobile apps: kho.unis.no/News/3xMobile.htm
- 1-7 days forecast from the University of Alaska Fairbanks: www.gi.alaska.edu/AuroraForecast
- Spaceweather.com gives updates about upcoming auroras, too — and many amateurs submit images of the latest auroras: www.spaceweather.com/
The substorm process is a hard thing to describe. It all starts when the extended feelers of the Sun’s magnetic field interact with Earth’s magnetic field. If the two fields point in opposite directions, they link up. This linking is called magnetic reconnection, and it happens when magnetic lines of force snap into new arrangements, releasing heat and energy. The process opens Earth’s field on the side facing the Sun, allowing particles and magnetic energy to enter our planet’s protective magnetic shield. This energy then travels to the nightside and stretches the shield’s tail, eventually causing it to pinch off and snap back toward the planet in an event called a substorm. When this substorm happens, it sends solar wind particles zooming to Earth’s polar regions.
The Conceptual Image Lab at NASA’s Goddard Space Flight Center created this great animation that shows the whole process.
As if the aurora’s sights weren’t enough, people have long heard clapping noises during auroral storms. Finnish scientists recently caught the sound on tape (the buzz is not the aurora, listen for the sharp sound):
The author of February's article, Pål Brekke, has coauthored a new book on the aurora, the preview video for which is below: