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Skywarden,
Ursa Astronomical Association
Kopernikuksentie 1
00130 Helsinki
taivaanvahti(at)ursa.fi

Ursa Astronomical Association

Active aurora band - 28.9.2020 at 21.15 - 28.9.2020 at 22.10 Hankasalmi Observation number 93981

Visibility III / V

Juha Kinnunen, Jyväskylän Sirius

The show started reasonably promising, soon after nine o'clock, but a fairly dense cloud cover spread to the scene as early as an hour later. Expectations were higher.



More similar observations
Additional information
  • Aurora brightness
    • Dim auroras
  • Colors with unaided eye and other features
    • Blue auroras info

      Clearly blue auroras can be seen only during the best aurora displays close to the maximum phase or soon after it. Sometimes blue auroras can be seen shortly after the sunset at the top part of the auroral shapes, specially rays. It is created by the mission of the ionized nitrogen molecules created by the suns radiation.

      Strongly colored blue auroras. Photo by Jorma Mäntylä.

      Blue top parts of the aurora. Image by Tom Eklund. 

      Blue top parts of the aurora. Image by Jaakko Hatanpää.

      Partly blue corona. Photo by Tapio Koski.

      Faintly blue top parts of an aurora veil. Photo by Jaakko Hatanpää.

    • Red coloration of the shapes lower edge info

      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 info

      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 info

      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 info

      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.

Technical information

Nikon D800 and Nikkor 14mm / 2.8

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