All-sky aurora - 8.10.2018 at 00.07 - 8.10.2018 at 23.50 Oulu Observation number 78264

Visibility V / V

Pertti Rautiainen

I went to photograph the northern lights in two installments, first from 9pm to 10pm, again at 11pm. Quite a nice and varied light show, but not as glorious as the great northern lights that were three years earlier. The clouds shining with light pollution brought a small aesthetic addition to some of the images.

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Additional information

Aurora brightness
- Bright auroras
Colors with unaided eye and other features
- Streaming auroras
  
  Streaming. In streaming aurora fast irregular variations in brightness occur along the horizontal dimension of homogeneous shapes.
- Green auroras
  
  Green, seen with the naked eye, is one the most common colors of the aurora. The green color is derived from atomic oxygen.
  
  Green auroras. Lea Rahtu-Korpela.
  
  Green auroras. Photo by Juha Ojanperä.

Observed aurora forms
- Band
  
  Bands are usually narrower, more twisty at the bottom, brighter, and more active than arches. Bands usually develop from arches.
  
  Bands can form J and U shapes, sometimes even full spirals. The corona can also arise from bands. Bands are a fairly common form of aurora.
  
  Aurora band. Photo by Merja Ruotsalainen.
  
  Aurora band. Photo by Matias Takala.
  
  Aurora band. Photo by Lea Rahtu-Korpela.
  
  Aurora bands. Photo by Lauri Koivuluoma.
  
  Aurora band. Photo by Matias Takala.
- Arc
  
  ARC The arcs are wider than the bands and do not fold as strongly. The arcs are normally neither very bright nor active.
  
  The arc is probably the most common form of aurora. When aurora show is a calm arc in the low northern sky it often doesn’t evolve to anything more during night. In more active shows the arc is often the first form to appear and the last to disappear.
  
  The lower edge of the arc is usually sharp but the upper edge can gradually blend into the background sky. As activity increases rays and folds normally develop, and the arcs turn gradually into bands.
  
  An aurora arc runs across the picture. Vertical shapes are rays. Photo by Atacan Ergin.
  
  Aurora Arc. Photo by Mauri Korpi.
  
  Aurora Arc. Photo by Anna-Liisa Sarajärvi.
  
  Aurora Arc. Photo by Matti Asumalahti.

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All-sky aurora - 8.10.2018 at 00.07 - 8.10.2018 at 23.50 Oulu Observation number 78264