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Ursa Astronomical Association

Quiet aurora arc - 13.8.2013 at 02.01 Tampere Observation number 16941

Visibility II / V

Jari Luomanen, Ursa (Länsi-Suomi)

A calm arc of northern lights and short-lived rays appeared for a moment to adorn the starry sky above the illuminating night clouds.



More similar observations
Additional information
  • Colors with unaided eye and other features
    • 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

    • Arc info

      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.

Comments: 4 pcs
Karri Pasanen - 13.8.2013 at 22.43 Report this

Hieno bongaus, taitaa ollakin ainoat kuvat näisät reposista :)

Jari Luomanen - 14.8.2013 at 10.20 Report this

Kiitos, ainakin Tom löysi kuvistaan reposet myös. Kauaa tuo ei kestänyt ja säteet kävivät näyttäytymässä vain minuutin verran. Itse huomasin reposet juuri säteistä - katsoin, että mitäs ne yökköset siellä elämöivät kunnes tajusin, että niiden päällä tanssii vihreä nauha. Tuli kiire zuumailla niitä vähän tarkemmin. :-D

Tom Eklund - 14.8.2013 at 19.53 Report this

Hienot kuvat, kuten aina tietysti, ja tosi kiva, että edes yksi sai oikeasti kuvattua nuo. Näiden ynnä muuta reposten kanssahan asian ydin on se, että ne eivät useinkaan liian kauan taivaalla viivy ja jos horisonttia ei katso koko ajan, todennäköisesti missaa reposet tai ainakin sen kirkkaan hetken. Minuuttihan on vielä melkein pitkä aika näille! :D

Jari Luomanen - 14.8.2013 at 20.15 Report this

Minuutti oli tosiaan pitkä aika näiden kanssa. :-D Tuossa ykköskuvassa näkyvät suht selvät säteet tulivat vain yhteen 30s valotukseen, toisessa ne ovat jo aika pliisuja.

Ja totta tosiaan, olet tismalleen oikeassa tuon herkeämättömän tarkkailun merkityksestä.

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