Greta Jimenez
Light pollution, caused by unwanted, excessive artificial lighting, is a growing problem. It can have adverse effects on human health and the environment, and its impact is increasing. To address this issue, it is essential to measure light pollution accurately. While there is no single device that meets all measurement objectives, several methods and tools are available to quantify light pollution, including satellite imagery, ground-based photometers, smartphone apps, and the Bortle scale. By using these techniques, scientists and citizen science programs can monitor and address light pollution to mitigate its effects on the environment and human well-being.
| Characteristics | Values |
|---|---|
| Understanding the magnitude of light pollution | Measure the brightness of the night sky |
| Tools to measure light pollution | SQM devices, smartphone apps, satellite imagery, ground-based photometers, photography, citizen science programs, etc. |
| Common standards for measurement | The Bortle scale, a nine-level measuring system, is used to track light pollution in the sky. |
| Impact of light pollution | 83% of the world's population lives under light-polluted skies. |
| Addressing light pollution | The International Dark-Sky Association designates areas with high-quality night skies. |
Explore related products
What You'll Learn
Using a Sky Quality Meter (SQM)
To measure light pollution, one must measure the brightness of the night sky. This can be done through citizen science programs and long-term monitoring. One such device used to measure light pollution is a Sky Quality Meter (SQM). SQMs are produced by the Canadian company Unihedron in Grimsby, Ontario.
There are several models of SQM, offering different fields of view (i.e. measuring different angular areas of the sky) and various automatic measurement and data logging or data communication capabilities. The SQM-L, for example, has an additional integrated lens, offering a narrower measurement range of 20° compared to the 84° range of the standard SQM model. The values reported by the SQM are in units of magnitudes per square arcsecond (mag arcsec^-2). The data provided by SQMs are recorded in magnitudes, denoted as m or mag, specifically in mSQM (or magSQM).
SQM response can be influenced by ambient temperature variations, so it is important to verify these effects. Since SQMs are not waterproof, they must be protected from moisture using housing, which is generally provided by the manufacturer. This housing protects the device but also traps the heat generated during operation, which is minimal for USB models (SQM-LU) but more significant for Ethernet models (SQM-LE). SQM-LU devices are stable within the temperature range of −15 °C to 35 °C, with variations smaller than the 10% systematic uncertainty state.
When SQMs are installed permanently outdoors for long-term monitoring, their sensitivity can degrade over time due to environmental exposure. A 2021 study demonstrated that this ageing effect, caused by factors such as reduced sensor sensitivity and optical degradation, can lead to the systematic darkening of measurements. Researchers proposed a correction method using twilight sky brightness as a natural calibration source. By comparing SQM readings under clear twilight conditions with empirical models, they derived linear degradation rates of 34-53 millimagnitudes/sqarcsec per year, depending on the location and latitude.
Power Delivery Pollution: America's Dirty Energy Secret
You may want to see also
Explore related products
Utilising smartphone apps
Light pollution is the human-made alteration of outdoor light levels from those occurring naturally. It has harmful effects on streetlights, greenhouses, and satellites, among other sources. To address this issue, smartphone apps have been developed to measure light pollution and its impact on the environment. These apps enable users to measure sky brightness and track light pollution, contributing valuable data to global research efforts.
One such app is Dark Sky Meter, which is currently available for iOS devices and costs $4.99 to download. This app uses the smartphone's camera sensor to measure the brightness of the night sky. To use the app, users take two photographs: a "dark shot" to calibrate the phone to complete darkness, and a second shot of the night sky. The app then provides a calibrated reading in standard astronomical units, allowing for comparisons across different devices and locations. Users can also track light pollution trends over time and contribute data to research projects.
Another app, Loss of the Night, is available for both Android and iOS users. This app prompts users with a star chart and asks if they can see increasingly fainter stars to determine the naked eye limiting magnitude. It also includes a 'nighttime' option that dims the screen and uses red colours to preserve dark vision. Loss of the Night guides users through the sky as measurements are made with a sensitive tool—the human eye.
Additionally, an app developed by a team of astronomers aims to address the challenge of measuring blue and red light by utilising citizen science. Users take pictures of light sources, and the app measures the light spectrum and estimates the amount of different colours. This data is then uploaded to a database tagged with the user's location and correlated with light pollution maps from satellites. By engaging citizen scientists, the astronomers aim to correct and calibrate satellite information to improve the accuracy of light pollution measurements.
These smartphone apps provide accessible tools for individuals to contribute to the understanding and mitigation of light pollution. By participating in citizen science projects, users can help address the harmful effects of light pollution on wildlife, human health, and astronomical observations.
Chicago's Beaches: Pollution and Environmental Concerns
You may want to see also
Explore related products
Taking photographs
Photography is an important method for measuring light pollution. Specialized CCD (charge-coupled device) cameras are used by the National Park Service (NPS) to capture light in the night sky, which scientists can then measure. The images are taken using a 50mm lens with an aperture of f2, which allows for a significant amount of light to enter the lens, making it ideal for low-light photography. The exposure time varies depending on the location—brighter urban areas may only require an exposure of one second or less, while darker natural parks might need up to 14 seconds.
The camera system is equipped with a modified telescope mount, tripod, customized scripts, filter wheels, and accessories. It is pre-programmed to automatically take a total of 45 images of the night sky. The telescope mount is directed by computer scripts to rotate the camera in specific directions to capture the entire sky, from the horizon to the zenith. This comprehensive set of images provides a full picture of the sky brightness, including all sources of light, both natural and artificial.
The images are internally stamped with important metadata, including the time, date, location, latitude, longitude, site elevation, and current weather measures. This ensures that the photographs are properly contextualized and enables effective data analysis. Additionally, the camera captures a reference image of the zenith at the beginning and end of each sequence to monitor any changes in sky conditions during the photography session.
The resulting photographs are then processed and combined to create a seamless 360-degree panorama of the sky. This mosaic of images provides a detailed representation of the light pollution in the area, with each mosaic containing millions of light measurement points. By comparing these measurements, scientists can assess the intensity and variations in light pollution across different landscapes.
It is important to note that there is currently no standardized method for recording measurements from these devices, which makes it challenging to compare data from different locations. However, citizen science programs, such as the Globe at Night project, encourage enthusiasts to participate in long-term monitoring and contribute to our understanding of light pollution.
Controlling Indoor Pollution: Tips for a Healthy Home
You may want to see also
Explore related products
![On the Brightness of the Sky & the Total Amount of Starlight... 1909 [Leather Bound]](https://m.media-amazon.com/images/I/617DLHXyzlL._AC_UL320_.jpg)
Citizen science programs
One of the citizen science campaigns supported by DarkSky International is Globe at Night, which aims to help understand sky glow and its impact. Globe at Night does not require any special tools, and observations can be easily reported via smartphone, tablet, or computer. Participants can also optionally provide data from a handheld sky quality meter (SQM) device. The Dark Sky Meter app, for example, uses the iPhone camera to record the brightness of the night sky, while the Loss of the Night app involves the human eye in the measurement process.
Another citizen science initiative is the Cabauw Lightmeter InterComparison (CLIC) workshop, which proposed a new standard format for recording sky glow measurements. This format is designed to make comparisons of future measurements easier, regardless of whether they are taken with current or future detectors. The community has also developed the PySQM program to collect and download night sky data, with compatible programs available from the SQM Reader website by Knightware.
In addition to these programs, there are various tools and techniques available for citizen scientists to measure light pollution. These include single-channel photometers, all-sky cameras, drones, and wearable devices such as wristwatches, pendants, or head-mounted devices. NASA's Black Marble VIIRS suite is another example, providing high-quality nightly images with comprehensive metadata that can be used to estimate upward light emissions and full-sky brightness mapping.
Pollution's Deadly Impact on Sea Turtles
You may want to see also
Explore related products
The Bortle scale
There are a few ways to measure the Bortle scale of a particular location. One way is to use a light pollution map, which shows the amount of artificial light in an area and how bright the night sky will look. These maps can give an approximate reading for any location on Earth. Another way is to use a smartphone app such as Clear Outside, which uses your current GPS location to present an accurate reading of where your night sky lands on the Bortle scale.
It is important to note that there can be drastic differences between some classes on the Bortle scale, such as the difference between Bortle 4 and 5. This is because the scale's SQM's at the lowest are typically the same as the highest for the next class, but the 4-5 deviation from this pattern is significant.
While the Bortle scale is a useful tool, it is not the only way to measure light pollution. Other methods include using specialized tools such as sky quality meters (SQMs) and long-term monitoring programs such as the Globe at Night project.
Deforestation's Devastating Impact: Polluting Our Planet
You may want to see also
Frequently asked questions
Light pollution is the presence of any unwanted, inappropriate, or excessive artificial lighting.
Light pollution can compromise human health by disrupting sleep and suppressing melatonin. It can also prevent us from experiencing a natural night.
There are a few ways to measure light pollution. You can use a Sky Quality Meter (SQM) to measure the luminance of the night sky in magnitudes per square arcsecond. You can also use your smartphone with apps like Dark Sky Meter or Loss of the Night. Alternatively, you can take photos of the night sky and look for details and contrast.
The Bortle scale is a nine-level measuring system used to track the amount of light pollution in the sky. A lower number on the scale indicates better sky quality.
You can help measure light pollution by participating in citizen science programs like Globe at Night, which invites people to measure their night-sky brightness using constellations.
