Contact information

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

Ursa Astronomical Association

Kehä - 16.6.2018 at 13.00 Vaasa, Söderfjärden Observation number 74609

Visibility IV / V

Marko Myllyniemi, Lakeuden Ursa

I saw the second circle of the day in Vaasa, Söderfjärden, at the Meteoriihi Observatory's 10th anniversary celebrations.


Additional information
  • Lightsource of the phenomenon
    • Sunlight
  • Common atmospheric phenomena
    • Corona info

      Corona (of the sun) is a colored ring or series of rings visible in the immediate vicinity of the light source. It can appear in both clouds and fog.

      Coronae are formed in very small drops of water. The size of the droplets affects the size of the corona ring. The smaller the droplets on average, the larger the circle is.

      With the water droplets being about the same size as each other, a series of strongly colored corona rings can be seen in the sky. When the droplet size is wide, only one ring with faint colors is visible.

      A corona can also be formed by small ice crystals in the upper clouds, but such coronas are very faint.

      The corona phenomena identification in Skywatch is intended for different kinds of corona rings that appear around the Sun. The coronae of the moon and planets have their own phenomena identification selections.

      Unlike halo rings, which are located apart from the Sun or the Moon, the perimeters form a uniform field of light in the immediate vicinity of the celestial body.

      Corona. Image by Ismo Luukkonen.

      Corona in the morning mist. Photo by Iida Pennanen.

       

      The distortion of the corona is caused by changing droplet sizes in the cloud. Imabe by Eetu Saarti. 

      A solar corona on a thick cloud. The lack of colors and suble changes in shades is hinting about wide range of droplets in different sizes. Photo by Marko Riikonen

      Feeble vaque corona. Image by Matias Takala.

       

      If the size of the droplets changes drasticly, the corona may appear strongly distorted. Photo by Aki Taavitsainen.

Technical information

Canon EOS 70D, Sigma DC 18-250mm OS HSM

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