Research: Light pollution around the world also harms astronomy and affects the functioning of most of the major observatories
Since the beginning of the electric age, about 150 years ago, our environment has been filled with artificial lighting, and in recent years it has increased even more thanks to technology such as LED lighting, which allows strong light with reduced electricity consumption. Illumination of our natural environment due to human activity is also referred to as light pollution, a name that implies that along with its advantages it also has many negative sides: light pollution harms the quality of sleep of humans and disrupts the lives of nocturnal animals. A new study examined another effect of light pollution, the interference with performing astronomical studies.
The main tool used by us in the study of astronomical phenomena is the telescope. Telescopes collect radiation that reaches us from distant celestial bodies, allowing scientists to study them and learn about the nature of the universe. Optical telescopes operate in visible light (different from radio telescopes), and provide us with magnification of distant objects. The light pollution affects the optical observations and can disrupt them, because in many cases the telescopes observe faint objects, which can only be seen because they are brighter than the dark sky. However, when the sky is brighter, even at night, due to the artificial lighting, it is much more difficult to see pale sky objects even in telescopes. Large optical telescopes are often located in isolated areas to minimize light pollution, but according to the new research, they may no longer be protected from it either.
The researchers, from Spain, Chile and Italy, examined with the help of data collected from satellites the level of light pollution near the 28 star observatories that operate the largest optical telescopes in the world. They examined five parameters affected by light pollution: the brightness level of the peak of the sky (zenith) above the telescope, average at a distance of 60 degrees of arc from the zenith, average brightness over the entire sky, average brightness above the horizon and the brightness of the horizon itself. They found high levels of light pollution in the vicinity of these telescopes: in two-thirds of them, the pollution exceeded the limit harmful to astronomical observations by ten percent, and the situation is getting worse every year.
According to the researchers, we must take strict and uncompromising measures to reduce light pollution and its effects, and to enable the continuation of astronomical research, and of course to protect against environmental effects of light pollution, such as damage to biological diversity. Some of the ways to do this are to reduce the use of artificial lighting or to use weaker lighting that scatters light towards the ground instead of towards the sky. In recent years, the need to protect dark areas by defining them as starlight reserves has come up for discussion. In any case, raising awareness is the first step towards solving the problem.
Not enough darkness. Telescope against the background of bright city lights that make astronomical observations difficult Photo: Martin Podzorny, Shutterstock
Satellites also interfere
The new study joins a series of other studies on the subject, and raise alarming findings about the levels of light pollution around the world.
Another new phenomenon affecting astronomical research in recent years is the passage of many satellites in the field of view of the telescope. The number of satellite launches in recent years means that during long-exposure sky photography, satellites pass through the field of view of the telescope and cause interference to photography. These are mainly the small communication satellites from the Starlink network of the SpaceX company. The network already includes thousands of satellites, and the company intends to launch thousands more satellites in the coming years. Starlink is not the only satellite network. More companies are working to establish satellite networks, and the problem of interference to astronomical observations is expected to get worse.