Half-sky auroras - 23.3.2023 at 22.45 - 23.3.2023 at 23.52 Hyvinkää Observation number 113748

Copyright © 2023 Senni Rytkönen. All rights reserved.

Visibility IV / V

Senni Rytkönen, Turun Ursa

I was in Helsinki watching professor Brian Cox's lecture on cosmology when during the break I saw that a friend from Turku observed the northern lights and a rocket launch. I also noticed the Northern Lights alert. When the lecture was over, I stepped into the penetrating sea fog on the streets of Helsinki, so there was no hope of the aurora borealis. In the car on the way home to Hyvinkää, we peeked out of the fog curtain and luckily I was sitting in the seat of the scarecrow so I could tell that the sky was on fire! Even the sister who was driving said that "uh, it's in the cloud..for a moment, it's gone!" When the car stopped in front of the front door, we saw the zenith blazing in the fierce corona crown and we admired it for a long time. I moved inside to the shelter of the balcony, from where I could better observe the sky directly to the north and limit the glare of the street lamps. What a show! Bright green that almost tastes good in the mouth (granny smith apples, editor's note), red and even blue that can be seen with the eyes! First the aurora over half the sky with the corona, then active belts with rays. Sometimes the going calmed down, but did not dilute. All the time there was something moving and green. Even looking through the window from the inside, the green was noticeably visible even when teasing the street lights. Just!

I observed the play for more than an hour in total until fatigue took over. What a perfect evening for a stargazer, with first an inspiring lecture and then the heavenly lights!

The images have been ripped with the basic settings of the Huawei P30 Pro camera. This was the kind of experience where the handset could warm up in the pocket and the eyes could take in the beauty as it is.

This description has been automatically translated from Finnish. Click here to see the original text.

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Additional information

Aurora brightness
- Bright auroras
Observed aurora forms
- Corona
  
  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.
- 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.
- 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

Colors with unaided eye and other features
- 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.
- Red coloration of the shapes top
  
  Auroras which have red top part that can be seen with naked eye are most often observed in the bands and long rays. In this case the lower parts are usually green. If the upper parts are in sunlight, red may be stronger than green. This shade of red is due to the discharge of the excitation state of the atomic oxygen.
  
  Aurora that shift to reddish towards the top. Photo by Karri Pasanen.
  
  Red top in a aurora band. Photo by Simo Aikioniemi.
  
  Red at the top of the aurora. Picture of Tom Eklund.
- Pulsating auroras
  
  Pulsating aurora. The brightness of the pulsating aurora usually varies rhythmically over a period that can be only a fraction of a second at its fastest, but can also be several minutes. Pulsing usually only occurs in(strong auroral conditions) higher quality shows , especially towards the end of them. However, the pulsation may be followed by yet another eruption. Sometimes the variation in brightness is at the same stage in the whole form, whereby the whole form "turns on and off" at the same time. Pulsation is also found in arches and bands, but above all in spots..
- Flaming auroras
  
  Flaming. This rare subclass of aurora does not mean so much a single shape, but a large area in the sky. In the flaming aurora, bright waves that are sweeping upward towards the magnetic zenith emerge in the sky. Very rarely waves can wipe downwards. Bands are usually reported during flaming, less often spots.

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