Every year people all over the world see fewer and fewer stars in the sky.

Observations by professional and amateur scientists around the world in recent years have revealed a disturbing trend: the stars in the night sky are becoming harder to see due to rapidly increasing light pollution.

Stars are disappearing before our very eyes, often unbeknownst to us, at an impressive – or rather alarming – rate.

Almost one in three people in the world no longer see the stars

The change in the visibility of the stars corresponds to an annual increase in the brightness of the night sky of almost 10% over the past decade. This means that a child who at birth had 250 stars visible in the locality, today in the same locality after 18 years can observe a maximum of 100 stars, i.e. more than half have already become “invisible”.

With the naked eye of a person, several thousand stars should be visible in a clear dark sky. Unfortunately, it is estimated that around 30% of people worldwide – almost one in three – have already lost sight of our galaxy due to light pollution, and the problem is getting worse, according to new research.

The researchers of the international scientific project Globe at Night led by Christopher Kimb from the German Research Center for Geosciences (GFZ) in Potsdam and the University of the Ruhr-Bochum, who made the corresponding publication in the journal Scienceanalyzed data from 2011-2022, including a total of 51,351 naked-eye human observations of stars at approximately 19,300 locations in different countries, mainly in Europe (3,700) and North America (9,500).

Doubled the brightness of the night sky.

It has been estimated that the brightness of the night sky has doubled in less than eight years. The annual increase in luminosity, which ranges from nearly 7% in Europe to 10% in the US, is much larger than the increase in artificial illumination (about 2% per year) based on satellite radiation measurements.

This is mainly due to the fact that satellites measure light pollution by mainly registering light directed towards the sky, while citizens mainly suffer from horizontal light pollution, which is the largest.

In many populated areas of the Earth, the night sky never completely darkens, as there is a diffuse glow of artificial light in the atmosphere.

This light pollution makes it difficult to see the stars at night. The proliferation of LED lighting, which emits more blue light, to which the eyes are more sensitive, has worsened the situation.

In addition, light pollution disrupts the natural cycling from sunlight to stellar light and back again, a natural process by which biological organisms (including humans themselves) have evolved.

Past research has highlighted the impact of artificial lighting on the environment, including animals and insects, and more generally on ecosystems in Europe and elsewhere, and on human health.

Source: RES-IPE