Links About the Northern Lights

I often get questions about:
  •  What website gives the best information about space weather and aurora observing potentials?

I usually look at the Space Weather site and pull down  the right side menu - Space Weather Now option which shows a view from the POLAR satellite of the so-called auroral oval.  If you see a bright ring on the image, then you know that an aurora is going on right now.  The more intense  (redder) the oval, the stronger the display.  Stronger ovals tend to expand further equatorially and therefore become more visible in the Lower-48. 

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dials                                                     The Kp Index helps you determine aurora visibility.

However, despite an active sun which produces Coronal Mass Ejectionsthat heads towards the earth, not all CMEs create aurora. As noted by the left hand dial, the Bz component needs to be negative (have a southward deflection) for the solar energy to be drawn into the earth's upper atmosphere and be made visible.  The more negative the better. A positive Bz all but guarantees that the energy that creates the northern lights is deflected away from the earth and therefore will not cause any aurora to form. The higher the speed of the solar wind, the more energetic the aurora will be if it reaches the earth (middle dial). The right dial measures how dense the solar energy is. The higher the better for viewing the lights.

  • What is the best time of year and day to view the Northern Lights?
Observations from Yerkes Observatory during a 55 year period spanning 5 sunspot cycles did confirm that September and March are the most frequent months for auroras and January and July the least likely. This correlation was also apparently described by Mairan in 1733. Most of the solar activity comes from regions of the sun outside the solar equatorial band +/- 10 degrees to either side of the solar equator. The Earth in its orbit is inside this equatorial band during January and July, and when it is at its maximum heliographic latitudes in September and March, the Earth is in the zone of solar activity.  Despite the fact that most of the United States is located well below the zone of most activity near latitudes of 68 degrees, we get quite a number of Aurora Borealis sightings, even as far south as Arizona! From Fairbanks, Alaska, because of the midnight sun, all night twilight is too bright for the aurora to be seen from about 15 April to 15 August.

Typically in Fairbanks, a display lasts a few minutes and occurs a few times per night. Auroral activity is usually highest during the hours near midnight. During a moderate to large auroral display, which can last up to three hours, the amount of energy released is roughly equivalent to that of a small nuclear explosion.

 Here is a partial list that is culled from back issues of Sky and Telescope magazine:



For events and photos since 2000, see Spaceweather.com Aurora Archived Gallery
  •  Is there a forecast for when the aurora will be visible?
Yes, at:
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