The never-ending twilights of May

Bright nights are a phenomenon that occurs at latitudes between 53 and 60 degrees latitude North or South, starting in late April and ending at the beginning of August. Nights are dark no longer and plunged into an ever-ending twilight, changing the face of our night sky was we know it. Find out what is happening with stunning imagery from Denmark...

Danish people call it 'Lyse nætter', literally meaning 'bright nights'. This natural phenomenon occurs when the sun does not set lower than 18 degrees under the horizon. Under this zone, the light from the sun does not officially have an influence (unless another light phenomenon occurs, like zodiacal lights...) on the brightness of the sky, this is what we call astronomical night. When the sun is located between 0 and 18 degrees below the horizon, its light is more or less visible to the viewer, and it affects tremendously how we see the sky. This 'twilight' (after sunset) or 'dawn' (before sunrise) zone is divided into three sub-zones depending on the position of the sun. - When the sun is between 0 and 6 degrees below, one calls it civil twilight or dawn. The night sky is still very bright and vibrant, landcapes can easily be seen without any problem. This is usually when our kids can still play outside and see something. Only the brightest stars and planets can be seen. High clouds (like Cirrus) can take vibrant red and orange colors.

- When the sun is between 6 and 12 degrees, one calls it nautical twilight or dawn. This night sky gets considerably dimmer and one can start to spot fainter stars. Landscapes can still be distinguished but less and less clearly.

- When the sun is between 12 and 18 degrees, one calls it astronomical twilight or dawn. The sunlight only affects a very tiny arc on the horizon, making the night sky very dark, but still in blue. The Milky Way, which was washed out, becomes visible to the naked eye provided one is away from heavy light pollution. Landscapes are very dark and almost impossible to make out, especially when looking directly into the twilight/dawn.


At a latitude of 56-57 degrees North like Denmark, the sun never goes down below the astronomical twilight/dawn during late spring and summer days (Late April till early August), making the nights brighter and brighter towards the summer solstice. May is a month of transition in the southern Scandinavian country, but also a month of opportunity and hope. It's the month where a lot of sky phenomena can occur at the same time, making an astrophotographer's life very interesting!


May weather is way sunnier and clearer than the majority of the months of the year. Denmark is still under the influence of the west-bound Gulf Stream, but the hotter temperatures clear up the sky more often. It means a lot more opportunities for night-sky shooting!


The first two weeks of May still offer dark enough skies (astronomical twilight) to witness aurorae borealis, provided there is a good activity, a moonless and cloudless night. I shot some of the best aurora scenes last year at the beginning of May. I assembled a short compilation in a time lapse movie, so you can take my word for it! Look at how vibrant those solar storms were. The twilight makes them take beautiful colors and hues. A show that you surely can't miss if you are in Denmark at this period of the year!

"On May 9th 2016, a magical event occurred over the countries of southern Scandinavia. As a potentially solar storm had been forecast by the NOAA, I hurried outside to try and get at least some pictures, thinking that the bright nights would prevent me from seeing anything. At this time of year, the position of our Sun right under the horizon would outshine any other weak source of light including the well-known aurora borealis. However around 10.30pm, as I was all set upon one of the burial mounts of Ordrupnæs in the north-west of Sjælland in Denmark, huge beam-like structures pierced through the bright twilight. Then I knew that night was not going to be ordinary! The whole sky caught on fire and displayed blazing green, magenta and blue flames throughout the night. What I was witnessing for the first time was the most sustained and powerful G2-G3 solar storm of my four years in Denmark. I tried to set up my cameras in different scenes, but I did not want to go too far away for fear of missing the show. A usual sub-storm begins with an arc that builds up, explodes in hundreds of pillars and then resides with some pulsating aurora. May 9th aurora started as usual and exploded around midnight, but then its fire kept on giving until 2:30 am when the nautical dawn resurfaced. I tried to capture the show as well as I could, even though I was completely overwhelmed by my emotions. One of the scenes is taken very close to the ground, in an alley shaped by tractor tracks in a growing wheat field, and is one of my favorite aurora shots that I call 'microcosmos aurora'. It shows the phenomenon from another angle, to try and mimic how bug would visualize it. You are probably not used to seeing the aurora borealis like that on the horizon, but more overhead. In Denmark, they very rarely come above 50 degrees, but that gives us an advantage because we are seeing the full spectrum of colors and length of the beams from the edge of the solar storm, that are often hidden by the brightness of the greens at higher latitudes. I shot the scenes with the Sony a7rII and Canon 70D and my main challenge during the shooting was the heavy formation of due on my lenses, because of the falling temperature of May nights, the rising humidity from the ground in the filed causing the due point to rise."


While May is not the best month of the year for deep-sky observation, you should definitely consider shooting wide angle and medium format astrophotography. Our galaxy, the Milky Way is still visible, along with the rest of the night sky. The southern portion of the night sky is way darker, enabling you to still get decent shots around midnight/1 am, but you can also take awesome landscapes of the twilight. You can also gaze a some meteor showers, as well as some other possible events. Here is an assortment of the latest pictures I have taken around the 15th of May onwards.


Even though these night shining clouds merely appear when the Earth is at its farthest away from the sun (June, July), some sightings are still possible by the end of May, as the mesosphere gets colder. My goal is still to take a combined picture/movie of NLC and auroras! I also put together the best shots from last year as a teaser for the upcoming NLC season. One more reason to spend the late hours of the mild nights in Denmark!