The camera followed by fans of Aurora Borealis – the Northern Lights – is located in Finland’s darkest municipality

Monday 18.2.2019 : HEIKKI SULANDER

 

photo: Heikki Sulanderphoto: Heikki Sulanderphoto: Heikki Sulander

photo: Heikki Sulander

 We stood to examine the camera that half of Finland’s Northern Lights hunters take a look at online each evening. It wasn’t really that impressive, but it plays a vital role in catching the Northern Lights. A few moments later we would learn that in fact it was just a by-product of other types of skygazing.

Rather more interesting than the small All-Sky camera is the science that is conducted in Hankasalmi. In terms of actual purpose the All-Sky camera is a camera intended for examining cloud conditions when starting to use the equipment at the Hankasalmi observatory. From the material obtained by the camera we see, however, that in Central Finland too the Northern Lights can be observed really frequently. Below is video in which the events of the whole night have been condensed into one short segment on the Hankasalmi observatory’s YouTube channel.

(Video Northern Lights 17.3.2015)

Jyväskylän Sirius ry, the association that conducts the skygazing at the Hankasalmi observatory, and its chairman Arto Oksanen are known worldwide since important observations concerning night sky phenomena are made on a regular basis in this dark corner of Central Finland.

Northern Lightsphoto: Heikki Sulander

 

Oksanen took us on a tour of the Hankasalmi observatory one day in autumn. The sun was shining beautifully as we drove into the farm compound where the observatory is located. Since the observatory is on private property restrained behaviour is called for as we make our approach. The Hankasalmi observatory no longer opens its doors to the general public so if the intention is to visit a private showing must be arranged with Sirius ry.

Will we soon be able to hear the sound of the Northern Lights?

By the end of 2019 a new research project will commence at the observatory the subject of which is controversial: do the Northern Lights generate sounds, can we hear them on the surface of the earth and how are they formed? Highly sensitive microphones will be installed in Central Finland’s Hankasalmi to listen to the heavens – since earlier it has been established that sounds may well be more easily detectable right here rather than in more northerly parts of Finland.

The sounds produced by the Northern Lights were already discussed in Norway at the beginning of the 20th century and at that time the general opinion was that the sounds were emanating from the measuring equipment or that a magnetic storm was creating sounds on the surface of the earth. In the 1960s the idea of the Northern Lights producing sounds was discounted since a study conducted in Alaska involving an audio recording made over a complete winter showed no sounds from the Northern Lights. This study was carried out, however, during a winter when the Northern Lights were a rare occurrence.

In Finland Aalto University’s Emeritus Professor of Acoustics Unto K. Laine pondered the contradiction between scientific measurements and accounts put forward by ordinary people. In folklore the sound of the Northern Lights has always been a part of the tales told: sighing, crackling and booming. He continued his research tenaciously, even using his own money to finance it. It was not until 2016 that Unto K. Laine was able present the findings of his research: recorded sounds.

If recorded sounds from the Northern Lights are now obtained in Hankasalmi, it will be really big news and serve to confirm the results of Laine’s protracted research, says Arto Oksanen. He personally has never heard sounds from the Northern Lights but the “ears” of the research equipment to be employed are really sensitive compared to human hearing.

Spotting the Northern Lights in Central Finland

Heikki Sulander of the Rinkkaputki blog reveals that he saw the first Northern Lights of his life in Jyväskylä in 2015. Prior to that he had always believed that he had at least to be surrounded by higher fells in order to even countenance making such an observation. But there they were glowing greenly. We asked Arto Oksanen for his best tips on witnessing the Northern Lights in Central Finland.

The key requirements for viewing the Northern Lights are:

1) Unrestricted view to the north
2) Cloudless sky
3) Little or no light pollution

The third of these is not absolutely essential but does significantly assist with distinguishing colours. How well the Northern Lights can be seen depends entirely on how strong they are.

Taking photos of the Northern Lights does not differ hugely from astrophotography, though it is somewhat easier in the sense that the Northern Lights do not need to be brought out as much in post-processing: while there must be a way of keeping the camera completely still as well as the ability to adjust the aperture, shutter speed and ISO manually, the actual camera employed is not so relevant. For this purpose a wide-angle lens is a better choice, for instance, than a telephoto option.

Camera settings for shooting the Northern Lights

Heikki recommends the following: a shutter speed of 2-7 seconds (for really bright Northern Lights a shutter speed of less than a second is adequate), the largest possible aperture (in other words the lowest F-stop or “wide open”) and an ISO of between 800 and 2000. And manual focus naturally performed in such a way that the stars and lights are in correct focus – or “close to infinity”. It pays to remember that an over-long shutter speed will cause the Northern Lights to look less like colourful flames in the heavens and more like sky that has been photoshopped.

It should also be mentioned that during the season the Hankasalmi All-Sky camera captures the Northern Lights on virtually a weekly basis, so it cannot be regarded as a rare occurrence. You just need to be in the right place at the right time. It is also a good idea to subscribe to Revontulihälytin and receive an email alert whenever the probability of the Northern Lights occurring is high. On 8.10. a large number of emails hit the inbox, so fantastic was the show.

Another source of valuable advice on spying the Northern Lights is a new book, Revontulibongarin Opas (Into Kustannus Oy 2018, Palmroth, Jussila, Hotakainen), which examines the phenomenon in even greater detail.

So how do the Northern Lights come about?

When particles charged by the solar wind hit the earth’s atmosphere a phenomenon known as Aurora Borealis or the Northern Lights results. The closer to the poles, the more frequently the phenomenon occurs. The most powerful Northern lights are generally visible after strong flare bursts from the sun’s corona. In terms of colour the Northern Lights are usually green, but purple, blue and red hues also occur, depending on the excited states of oxygen and nitrogen atoms and molecules.

The most recent period of strong Northern Lights took place around October 7th-8th, and as you can see, it was a pretty impressive sight.

(Video Skywatch 2018 10 07)

 
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