Dates: days around the Solstice, 20 – 21 June
On the nights around the summer solstice in the northern hemisphere (20 and 21 June), twilight extends its influence further than we imagine, and prevents the night from closing (or shortens it considerably) in Europe, offering a natural spectacle that is magnified the further north it goes.
How it affects different regions:
- From the latitude of the French Finistère northwards: From the latitude of Brest, a city located in the north-west of France, and extending northwards, you do not experience a closed night at this time of year. Twilight keeps the sky illuminated throughout the night, creating a magical and ethereal atmosphere. From the Arctic Circle (which passes through the Finnish city of Rovaniemi), the sun does not set all day (midnight sun).
- South of Brest: South of Brest there are already closed night time bands, the length of which varies according to latitude. For example, in Galicia, northwest Spain, less than 4 hours of total darkness are experienced during these nights.
Cause of the Phenomenon
Twilight is a phenomenon that occurs when the sun is slightly below the horizon, providing indirect illumination that prevents total darkness. During the summer solstice, the sun reaches its highest point in the sky in the northern hemisphere and its path dips just below the horizon during the night in more northern latitudes.
Impact and Natural Beauty
This phenomenon is especially notable in regions near the Arctic Circle, where the «midnight sun» can be experienced: the sun does not set completely throughout the day. Although at more southerly latitudes, such as Brest and Galicia, the sun does set, the prolonged twilight provides nights of magical clarity.
Recommendations
For those who wish to enjoy this natural spectacle, it is recommended to look for places with low light pollution to fully appreciate the beauty of the night sky illuminated by twilight. It is also a good opportunity for lovers of photography and astronomical observation.
In short, the nights of the summer solstice offer a special occasion to contemplate nature at its best, with the twilight adding a touch of magic to the shortest nights of the year.
Jorge Mira (University of Santiago de Compostela)
Jose-Maria Martin-Olalla (University of Sevilla)