Contact information

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

Ursa Astronomical Association

All-sky aurora - 26.9.2020 at 02.30 - 26.9.2020 at 02.45 Kolari Observation number 94011

Visibility V / V

Pasi Tuomainen, Ursa (Itä-Suomi)

In Ylläs in the morning 26.9. when I filmed, there was quite a show on offer. As I unpacked the images, I began to wonder more closely about these shapes, and how long they lasted. The pictures show a horseshoe-like shape that lasted 20 minutes in the sky! I took a timelapse while photographing that little cottage. Is this an Omega arc, then, or what? That edge was really impressive, and then it continued after a sharp angle as a longer straighter section that can be seen on top of that bigger building.



More similar observations
Additional information
  • Aurora brightness
    • Bright auroras
  • Observed aurora forms
    • Form not identifiable info

      Form not identifiable
      Sometimes auroras have to be observed in such poor conditions that it is not possible to reliably identify the shape even if for example the structure and conditions could be recognized. Such a situation could be the outcome of for example alight background sky, cloud cover or a covered horizon.

    • 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.

    • Corona info

      CoronaA corona is a hand fan shaped structure, it usually forms south of the observer's zenith, most commonly consisting of rays or bands. The corona is usually the most beautiful part of the aurora show. It is bright and active, but on the other hand also short-lived.

      Aurora corona. Photo by Anna-Liisa Sarajärvi.

      Aurora corona. Photo by Merja Ruotsalainen.

      Corona formed from bands. Photo by Markku Ruonala.

      Aurora corona. Photo by Tapio Koski.

Technical information

Nikon D800, Sigma 20mm f / 1.4 @ f / 1.4. ISO 1000. Exposures 1.6 s - 2.5 s.

Comments: 1 pcs
Pasi Tuomainen - 30.9.2020 at 17.06 Report this

Tuossa ilmansuuntia tarkastellessani, huomasin, että itse asiassa pohjoistaivas tyhjeni revontulista melkein kokonaan, ne painuivat kohti etelää. Tuo "hevosenkenkä" aukeama oli siis pohjoista kohti. 

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