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Ursa Astronomical Association

Half-sky auroras - 17.4.2021 at 02.00 Vaasa Observation number 97711

Visibility IV / V

Timo Alanko, Vaasan Andromeda

There was plenty of greenery all night. Here are a few highlights from Gopron’s night child.

Edit. In one exposure, the Gopro cell has received its turbine from a cosmic ray, according to the jury. I added a couple of pictures to the end. In addition to the scratching of the beam, yes, that red hemisphere next to the scratching is a bit surprising. There is nothing before and after that box.

More similar observations
Additional information
  • Aurora brightness
    • Bright auroras
  • Observed aurora forms
    • Veil info

      Veil is the most bland and very common form of aurora. It usually covers its homogeneous dim glow over a wide area of the sky at once. Most often, the veil is seen in the calmer and quiet phase of the night after the aurora maximum as a background for other forms. The veil can also occur alone and in that case it will be quite difficult to reliably identify as an aurora, especially at a observation site which has a lot of light pollution.

      A similar glow of light can also be caused by airborne moisture, smoke, or a very thin layer of clouds that reflects the light that hits them. However, clouds can also be used to identify veil, especially if the middle or upper cloud appears dark against a lighter background, then it is very likely to be aurora veil if the brightness of the background sky is not due to the rising or falling Moon or Sun. When photographing, very long exposure times usually reveal the green colour of the veil auroras.

      Veil and rays. Photo by Esa Palmi.

      Red aurora veil. Photo by Marko Mikkilä.


      Veil. Photo by Milla Myllymaa.


      Aurora veil that changes color from green at the lower edge through purple to blue at the top. Photo by Jaakko Hatanpää.


      Dim green veil. Photo by Jarmo Leskinen.


      Radial aurora band surrounded by veil. Photo by Jussi Alanenpää.

    • 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.

    • 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: 8 pcs
Marko Myllyniemi - 17.4.2021 at 10.01 Report this

Nyt oli tosiaan varsin näyttävät revontulet pitkästä aikaa.

Timo Alanko - 17.4.2021 at 16.24 Report this

Nostin hiukan kuvien kirkkautta, ja näyttääpä goprokin saaneen mukaan keltaista väriä. 

Timo Alanko - 18.4.2021 at 09.45 Report this

Huom! Lisäsin pari vähän kummallisempaa kuvaa syynättäväksi.

Marko Myllyniemi - 18.4.2021 at 23.02 Report this

Enpä ole aiemmin nähnyt kosmisen säteen aiheuttamaa "naarmua" kuvassa, näyttää varsin jännältä (ja hyvä tietää, mikäli osuu joskus omalle kohdalle, että mikä ihme...)

Kaj Höglund - 20.4.2021 at 08.33 Report this

Hieno video! Jännittävä havainto mahdollisesta kosmisesta säteestä!

Tapio Lahtinen - 20.4.2021 at 09.34 Report this

Kyllähän noita kosmisen säteen osumia usein sattuu kennolle.
Mutta tuo punainen välähdys näyttää erikoisemmalle.

Timo Kuhmonen - 20.4.2021 at 19.46 Report this

Omalla tulipallokameralla (Watec910) kosmisen säteen osumia tulee silloin tällöin. Jotkut niistä saattaa hämäävästi näyttää tulipallolta peak hold -kuvassa. Kuitenkin videon toistaminen erottaa ne. Tuollainen jälki näkyy kyseisessä kamerassa yhdessä framessa, kun 25fps video on katsottu läpi. Tulipallossa erottuu liike...

Timo Alanko - 20.4.2021 at 20.00 Report this

Tuo punainen puolipallo. Mikä sen selittäisi. Valitettavasti goprossa ei ollut RAW - tallennus päällä... 

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