An international team of scientists, through observations and measurements, has calculated the area with the darkest sky. There, only 2% of artificial light hinders observers.
The research team collected photometric data at 44 locations around the world. So they want to quantify how dark the night sky is around the globe. They found out that the darkest sky is over the Canary Islands.
The project’s lead researcher, astronomer Miguel Alarcón, is a native of these islands off the west coast of Africa. The work, which will be published in the next issue of The Astronomical Journal, used a series of photometers called TESS. So scientists wanted to get a basic understanding of the darkness of the sky.
The team collected 11 million data points from as far apart as Namibia, Australia and the United States. While this number did not include some popular astronomer sites (such as the highlands of Antarctica), it was a good sample of different conditions for observing the sky. The researchers noted that the Canary Islands experienced the lowest level of background light. Only about 2% of the light comes from artificial lighting at the Roque de los Muchachos observatory on the island of Palma.
However, scientists note that dark skies are not necessarily ideal conditions for observing. They also need to consider other factors, such as atmospheric visibility and temperature fluctuations, which can cause observational problems. The main takeaway from this study is that if you want to see the night sky, it is worth going to the islands off the coast of Africa.
However, there are other, natural sources of light pollution that affect different geographic regions in different ways. The moon and the Milky Way are standard features of the night sky and certainly contribute to its natural brightness. However, there are other, more variable sources that have been observed in this study. These include the glow in the upper atmosphere, which is caused by a combination of factors such as the solar cycle, geographic location, and season.