Deutsches GeoForschungsZentrum GFZ
14473 Potsdam, Germany
interactive scape GmbH
Köpenicker Str. 48/49
10179 Berlin, Germany
Tel: +49 30 69 80 941 - 00
This web application was developed to make skyglow data collected by citizen scientists easily accessible, and to provide some basic tools for citizen scientists to visualize the data they have collected.
Skyglow is the artificial brightening of the night sky. It is mainly caused by lamps that radiate some fraction of their light directly into the sky, rather than onto sidewalks and streets. There is currently a debate about whether LED streetlights will make the sky brighter or darker. Data collected by citizen scientists is needed to tell us the answer.
The application displays data from four different sources:
- Visual observations from the Loss of the Night app (Android and iOS)
- Visual observations from the Globe at Night project
- Observations taken with a Sky Quality Meter
- Observations from the Dark Sky Meter app (iOS only)
To start, click the blue rectangle at the top right of the map page. There you can select the years and types of measurements you would like to display. When you have chosen, click "Load selection".
The map will now display the number of observations taken in different regions of the world. Zoom in to get closer to your region of interest, and then click on a point or circle to bring up information about measurements taken there. The information will appear in a new blue box.
For data collected from the Loss of the Night app, a chart will appear showing details of which stars the citizen scientist observed. A white line shows the estimated naked eye limiting magnitude, and a colored bar shows over what range the citizen scientist was able to make self-consistent observations. A narrow bar means that the data are very self-consistent, a wider bar means that the uncertainty on the observation is larger. As users gain experience using the app, their error bars tend to become smaller.
The top blue box also allows you to do a "trend analysis" for observations taken in a small area. At zoom level 13 or higher, you can define an area over which you'd like to see the change over time. Click the "start" button, then click on the map and drag away from the point you clicked until the circle covers the area you are interested in. When you unclick, a chart will pop up showing how the sky brightness has changed over time. To avoid having an effect due to different locations rather than real changes in sky brightness, only use a circle radius of several hundred meters or smaller. The sky brightness changes from night to night, so the more observations there are from a single location, the more accurate the average is.
The data that goes back furthest in time is from the Globe at Night project. Unfortunately, this data is the least precise, and it will only be possible to see local trends over long time periods and with very many observations. (The data is extremely useful for regional and global analyses, but this requires a more sophisticated analysis that takes the different observation locations into account.)
In the coming years, the more precise data from the apps and Sky Quality Meters should be able to demonstrate changes in individual locations that experience a large change in sky brightness during a short time scale. This could happen due to a change in street lamp type, or bright illumination from a new development like a shopping mall.
You can become a citizen scientist and start a time series at your home! Just click on the links to the projects above, and start observing on starlit nights!
Why is skyglow important?
Artificial skyglow is a major change to Earth's biosphere. Many areas of the European Union and the USA now only experience day and twilight conditions: night doesn't happen anymore. This is very concerning, because about 2/3 of invertebrates are nocturnal, and their natural habitat has been lost.
Can't you just use satellite images?
Satellite images are great for seeing changes on the ground, but they can't tell us about what's happening to the sky. Additionally, the best current available satellite has no sensitivity to blue light, and most "white" LEDs emit more blue light than older lighting technologies. A switch to LEDs can actually make a city look darker to the satellite, even if the blue light makes the sky a lot brighter!
I made an observation. Why don't I see it on the map?
The database is refreshed daily, so you might have to wait a day to see your observation. There are also some observations we don't show, for example cases where there is moonlight or twilight, clouds or fog. We also don't show data from the Loss of the Night app if the user didn't observe at least 7 stars, or if the data were not at all self-consistent. If you provided an email address from within the Loss of the Night app, you can view your own measurements from the "My Measurements" tab.
Why isn't my observation at the correct location?
Skyglow typically only changes with distances larger than about 100 meters, so we've decided to round the locations to 3 decimal places in longitude and latitude. In cities, this provides some measure of privacy, as you can't tell whose backyard the observation was made in.
Why are the error bars so large on the trend plots?
The displayed error bars include a combination of our best estimates for the systematic uncertainty associated with individual measurements plus the standard deviation of the mean of the observations for a given year. These errors are for the average observer, so in the case of especially careful observers they likely overestimate the true size of the systematic uncertainty.
Where can I learn more about skyglow?
A good place to start is the website of the International Dark-Sky Association (IDA). If you're interested in research into the effects of artificial light, check out the literature database established jointly by the European "Loss of the Night Network" and the IDA. If you prefer videos, you can watch a humorous 10 minute talk about light pollution and ecology, or a 20 minute documentary about the related "Loss of the Night" project.
I have a table of SQM data. How can I get it displayed here?
We would be very happy to add your personal database of handheld SQM-L observations into our database! Just contact Christopher Kyba for details on how this can be arranged. If you have data from a permanent station (SQM-LE, SQM-LU, or SQM-LU-DL), a sister project is just getting started to handle this sort of data. Contact Christopher Kyba for details.
How can I help?
There are lots of ways to help! You can:
- Make an observation using one of the four methods listed at the top
- Tell your friends about this project on social media, and follow us on twitter and facebook
- Contact your elected city representatives and let them know that quality lighting is important to you
- Use your knowledge of local geography to classify images of cities at night from the International Space Station
- Support the economy of areas that protect the night sky by visiting a Dark Sky Park
- Make a donation or become a member of the International Dark-Sky Association
- If you represent a charitable foundation, you could have an extraordinary impact by providing a grant to our research program. Christopher Kyba would be happy to talk with you about potential projects.
Funding and legal details
This application has been developed within the MyGEOSS project, which has received funding from the European Union's Horizon 2020 research and innovation programme. The JRC, or as the case may be the European Commission, shall not be held liable for any direct or indirect, incidental, consequential or other damages, including but not limited to the loss of data, loss of profits, or any other financial loss arising from the use of this application, or inability to use it, even if the JRC is notified of the possibility of such damages.
Implementation by interactive scape.