Active aurora band - 8.2.2021 at 23.00 - 8.2.2021 at 23.56 Vaasa, Vähäkyrö Observation number 95965

Copyright © 2021 Satu Rajamäki. All rights reserved.

Visibility III / V

Satu Rajamäki

I had popped in for a moment to photograph the starry sky and found that at very low it shows green with a long exposure. I thought the evening was in it. Wrong! Almost immediately back to the stations and for the next hour was allowed to follow the northern lights display. I photographed the northern lights between about 11 p.m. The arc of northern lights and the belt were visible, as well as the rays during the last show. The class was nicely active all the time. A few times, the red bottom was also visible to the naked eye. According to the car's meter, it was -21 degrees below zero. Northern lights were widespread from west to east. Not a 14mm tube was enough to get one picture of the whole view. Great evening though.

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Additional information

Aurora brightness
- Bright auroras
Colors with unaided eye and other features
- Red coloration of the shapes lower edge
  
  Red lower edge visible with the naked eye. The bands which are starting to level up their activity and are green colored have quite often a narrow red lower edge. This is the most common form of red color which is derived from molecular nitrogen.
  
  Aurora band with purple lower edge. Photo by Ilmo Kemppainen.
  
  The low hanging brightest aurora band is colored red at the lower edge. Photo by Tero Ohranen.
  
  Narrow purple reddish tones at the lower part of this aurora band. Photo by Merja Ruotsalainen.
  
  Purple band at the bottom. Photo by Panu Lahtinen.
- 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
- Rays
  
  The raysare parallel to the lines of force of the magnetic field, i.e. quite vertical, usually less than one degree thick light streaks. The rays can occur alone or in connection with other shapes, mainly with arcs and bands. Short rays are usually brightest at the bottom but dim quickly. The longest rays, even extending almost from the horizon to the zenith, are usually uniformly bright and quite calm, and unlike the shorter rays, most often occur in groups of a few rays or alone. Rays, like bands, are a very typical form of aurora.
  
  Artificial light pillars, which are a halo phenomenon visible in ice mist, can sometimes be very similar to the rays of aurora. Confusion is possible especially when the lamps that cause the artificial light pillars are far away and not visible behind buildings or the forest. The nature of the phenomenon is clear at least from the photographs.
  
  Rays. Picture of Tom Eklund.
  
  Rays. Photo by Mika Puurula.
  
  Two beams rise from the aurora veil. Photo by Anssi Mäntylä.
  
  Two radial bands. Show Jani Lauanne.
  
  Radial band and veil. Photo by Jussi Alanenpää.
  
  Two rays. Photo by Aki Taavitsainen.
  
  It may be possible to confuse such rays with artificial light columns. Compare the image below. Picture of Tom Eklund.
  
  There is no aurora in this image, but all the light poles - including the wide and diffuse bar seen at the top left - are artificial light pillars born of ice mist. Photo by Sami Jumppanen.
  
  Aurora and artificial light pillars. All the radial shapes in the picture above are probably artificial light pillars that coincide appropriately with the aurora band. In the image below, the aurora band has shifted and does not overlap with the pillars produced by the orange bulbs. There is no orange in auroras. Photo by Katariina Roiha
- 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.

Technical information

Exposure times were in the 2-4 sec range, aperture f2.8 and 14mm tube.

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