Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Patterns in sky brightness depend very strongly on location

12.02.2015

At many locations around the world, the night sky shines hundreds of times brighter than it did before the introduction of artificial light. Berlin based researchers from the Leibniz-Institute of Freshwater Ecology and Inland Fisheries (IGB) and the Freie Universität Berlin led a groundbreaking study into variations in the radiance of the night sky. Together with an international team of researchers from Europe, North America, and Asia, they found remarkably large variations in artificial night sky brightness at the different observation sites.

Light allows us to extend the day, increasing productivity. But the introduction of light into the nighttime environment is one of the most striking changes humans have made to the Earth’s physical environment, and it is associated with several unintended negative consequences.


In natural areas like Glacier National Park in the USA, clouds make the sky darker. In cities like Berlin they make it far brighter.

Photo credits: Ray Stinson (left) Christopher Kyba (right)

One example is skyglow, the artificial brightening of the night sky. Until now, all published skyglow research had been local or regional in scale. The new study greatly expands on this earlier work, examining light patterns at 50 locations worldwide. Most of the study sites had considerable skyglow: at 30 of the study sites, the sky was more than twice as bright as a natural star-filled sky more than 95% of the time.

The study, published Thursday in Nature Publishing Group's open access journal "Scientific Reports", is the most comprehensive examination of skyglow ever undertaken.

Cloudy nights are the most important

The study examined the effect that clouds have on the night sky brightness, and found that it varies remarkably, depending on the location. “Thick clouds act like a surface and scatter light back in the direction it came from” said study leader Dr. Christopher Kyba, study leader and former IGB researcher now based at the German Research Centre for Geosciences (GFZ).

For millions of years, this made overcast nights the darkest, with starlight reflected back into space. However, this occurred at only 2 of the 22 sites where nearby meteorological observations were available. At most sites, the overcast nights were many times brighter than clear nights. The researchers were surprised to discover that the ratio between overcast and clear sky brightness grows most rapidly as cities are approached. Once the city limit is crossed, the rate of this increase appears to slow.

The brightest individual observation came from a site near the Dutch town of Schipluiden. There, the sky was 10,000 times brighter than the darkest observation reported from Kitt Peak in the USA. “This difference is much larger than what is observed in the daytime” said Kyba. “It is roughly comparable to the difference between a surface illuminated by direct sunlight and one in the dim area between two street lamps.”

Even when the researchers restricted their analysis to average sky brightness at midnight, large differences remained. “Overcast nights in Berlin were typically 300 times brighter than those on the Dutch island of Schiermonnikoog in the North Sea” said Kai Pong Tong, the study’s second author and a PhD student at the University of Bremen.

Unforeseen consequences of lighting

The impact of brighter nights on the natural environment is still largely unknown. Researchers hypothesize that this change affects the behavior of nocturnal animals, affects navigation and migration for some species, and unbalances traditional predator-prey relationships. Even social interactions such as reproduction are believed to be affected.

Kyba points out that although the present study is the most widespread to date, it considered only a small fraction of the Earth’s nightly lit area. The researchers call for an international network of similar monitoring stations. The data gathered by such a network would allow researchers to calibrate and test models that predict skyglow in areas for which monitoring doesn’t exist. “Models will be an essential tool to understand the social and environmental impacts of skyglow” according to Kyba.

Lead author contact:
Dr. Christopher Kyba
Deutsches GeoForschungsZentrum, Potsdam and
Leibniz-Institute of Freshwater Ecology and Inland Fisheries (IGB), Berlin
Telephone: +49 (0)331 288 28973
Email: kyba@gfz-potsdam.de

Additional contacts by country:

CANADA:
Dr. Phil Langill
Rothney Astrophysical Observatory, University of Calgary, Canada
Telephone: +1 403 874 1877
Email: pplangil@ucalgary.ca

GERMANY:
PD Dr. Franz Hölker
Leibniz-Institute of Freshwater Ecology and Inland Fisheries (IGB), Berlin
Telephone: +49 (0)30 64 181 665
E-Mail: hoelker@igb-berlin.de

PD Dr. Axel Schwope
Leibniz-Institut für Astrophysik Potsdam (AIP), Potsdam, Germany
Telephone: +49-331-7499232
Email: aschwope@aip.de

Dr. Georg Heygster
Universität Bremen, Institute of Environmental Physics, Bremen, Germany
Telephone +49 421-218-62180
Email: heygster@uni-bremen.de

ITALY:
Dr. Andrea Giacomelli
Institute, City, Country: Attivarti.org, Torniella, Italy
Telephone: +393471533857
E-Mail: info@pibinko.org

UNITED KINGDOM:
Dr Thomas Davies
University of Exeter, Penryn, UK
Telephone: (+44) 1326259476
E-Mail: Thomas.Davies@exeter.ac.uk

Press images:
In natural areas like Glacier National Park in the USA, clouds make the sky darker. In cities like Berlin they make it far brighter. (Photo credits: Ray Stinson (left) Christopher Kyba (right))

Panel A shows the radiance at Kitt Peak relative to a natural starry sky (NSU=1), where clouds make the sky darker. Panel B shows the radiance in central Berlin. The upper and lower bands correspond to overcast and clear skies, and the radiance can be seen to decrease as the night progresses.

Source:
Kyba C.C.M. et al. (2015): Worldwide variations in artificial skyglow. Scientific Reports 5:8409. DOI: 10.1038/srep08409.

About the IGB:
The Leibniz-Institute of Freshwater Ecology and Inland Fisheries, IGB, is an independent and interdisciplinary research centre dedicated to the creation, dissemination, and application of knowledge about freshwater ecosystems. Working in close partnership with the scientific community, government agencies, as well as the private sector, guarantees the development of innovative solutions to the most pressing challenges facing freshwater ecosystems and human societies.

Weitere Informationen:

http://www.igb-berlin.de

Karl-Heinz Karisch | Forschungsverbund Berlin e.V.

More articles from Studies and Analyses:

nachricht The importance of biodiversity in forests could increase due to climate change
17.11.2017 | Deutsches Zentrum für integrative Biodiversitätsforschung (iDiv) Halle-Jena-Leipzig

nachricht Win-win strategies for climate and food security
02.10.2017 | International Institute for Applied Systems Analysis (IIASA)

All articles from Studies and Analyses >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Frictional Heat Powers Hydrothermal Activity on Enceladus

Computer simulation shows how the icy moon heats water in a porous rock core

Heat from the friction of rocks caused by tidal forces could be the “engine” for the hydrothermal activity on Saturn's moon Enceladus. This presupposes that...

Im Focus: Nanoparticles help with malaria diagnosis – new rapid test in development

The WHO reports an estimated 429,000 malaria deaths each year. The disease mostly affects tropical and subtropical regions and in particular the African continent. The Fraunhofer Institute for Silicate Research ISC teamed up with the Fraunhofer Institute for Molecular Biology and Applied Ecology IME and the Institute of Tropical Medicine at the University of Tübingen for a new test method to detect malaria parasites in blood. The idea of the research project “NanoFRET” is to develop a highly sensitive and reliable rapid diagnostic test so that patient treatment can begin as early as possible.

Malaria is caused by parasites transmitted by mosquito bite. The most dangerous form of malaria is malaria tropica. Left untreated, it is fatal in most cases....

Im Focus: A “cosmic snake” reveals the structure of remote galaxies

The formation of stars in distant galaxies is still largely unexplored. For the first time, astron-omers at the University of Geneva have now been able to closely observe a star system six billion light-years away. In doing so, they are confirming earlier simulations made by the University of Zurich. One special effect is made possible by the multiple reflections of images that run through the cosmos like a snake.

Today, astronomers have a pretty accurate idea of how stars were formed in the recent cosmic past. But do these laws also apply to older galaxies? For around a...

Im Focus: Visual intelligence is not the same as IQ

Just because someone is smart and well-motivated doesn't mean he or she can learn the visual skills needed to excel at tasks like matching fingerprints, interpreting medical X-rays, keeping track of aircraft on radar displays or forensic face matching.

That is the implication of a new study which shows for the first time that there is a broad range of differences in people's visual ability and that these...

Im Focus: Novel Nano-CT device creates high-resolution 3D-X-rays of tiny velvet worm legs

Computer Tomography (CT) is a standard procedure in hospitals, but so far, the technology has not been suitable for imaging extremely small objects. In PNAS, a team from the Technical University of Munich (TUM) describes a Nano-CT device that creates three-dimensional x-ray images at resolutions up to 100 nanometers. The first test application: Together with colleagues from the University of Kassel and Helmholtz-Zentrum Geesthacht the researchers analyzed the locomotory system of a velvet worm.

During a CT analysis, the object under investigation is x-rayed and a detector measures the respective amount of radiation absorbed from various angles....

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Ecology Across Borders: International conference brings together 1,500 ecologists

15.11.2017 | Event News

Road into laboratory: Users discuss biaxial fatigue-testing for car and truck wheel

15.11.2017 | Event News

#Berlin5GWeek: The right network for Industry 4.0

30.10.2017 | Event News

 
Latest News

Underwater acoustic localization of marine mammals and vehicles

23.11.2017 | Information Technology

Enhancing the quantum sensing capabilities of diamond

23.11.2017 | Physics and Astronomy

Meadows beat out shrubs when it comes to storing carbon

23.11.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>