Major astronomical observatories across the world have had their levels of light pollution examined and compared by researchers from Italy, Chile, and Galicia.

Major astronomical observatories across the world have had their levels of light pollution examined and compared by researchers from Italy, Chile, and Galicia.

The analysis demonstrates that artificial light is contaminating the sky over most observatories and that prompt action is required to lessen the level of pollution.

The analysis demonstrates that artificial light is contaminating the sky over most observatories and that prompt action is required to lessen the level of pollution.

Monthly Notices of the Royal Astronomical Society published the research.

Monthly Notices of the Royal Astronomical Society published the research.

The study shows the levels of light pollution above nearly 50 observatories throughout the world, including the biggest professional observatories and smaller amateur observatories.

The study shows the levels of light pollution above nearly 50 observatories throughout the world, including the biggest professional observatories and smaller amateur observatories.

The study uses nighttime satellite data to apply a model of light propagation in the Earth's atmosphere.

The study uses nighttime satellite data to apply a model of light propagation in the Earth's atmosphere.

The night sky at significant observatory locations is more polluted than one may anticipate when using various light pollution indicators in addition to the conventional brightness immediately overhead.

The night sky at significant observatory locations is more polluted than one may anticipate when using various light pollution indicators in addition to the conventional brightness immediately overhead.

One of the characteristics used to categorise the study sites is the zenith, which is often the less polluted and thus darker region of the night sky.

One of the characteristics used to categorise the study sites is the zenith, which is often the less polluted and thus darker region of the night sky.

One of the characteristics used to categorise the study sites is the zenith, which is often the less polluted and thus darker region of the night sky.

One of the characteristics used to categorise the study sites is the zenith, which is often the less polluted and thus darker region of the night sky.