The 2007 Great World Wide Star Count

Looking Back: The 2007 Great World Wide Star Count

Kirsten K. Meymaris, Dennis L.Ward, Dr. Sandra Henderson University Corporation for Atmospheric Research, Office of Education and Outreach

Introduction What can you see when you look up at the nighttime sky? Do you see stars, constellations, satellites, or the Milky Way? For many people around the world, the Milky Way is something described only in books and in pictures, not something visible in their nighttime sky. However, even though we might not be able to see the Milky Way does not mean its not there! Astronomers have long known that light pollution impairs our ability to clearly see the night skies and now the general public is also experiencing this phenomenon. Light pollution is often described as an undesirable byproduct of our industrialized civilization. Light pollution can be simply defined as excessive illumination due to human activity. It is a broad term that refers to multiple problems, all of which are caused by inefficient, annoying, or arguably unnecessary use of artificial light.

Recognizing the interest and concern regarding the decreasing quality of our night skies, UCAR’s Windows to the Universe (www.windows.ucar.edu) launched a new citizen science project in October 2007, The Great World Wide Star Count (GWWSC, www.windows.ucar.edu/starcount). This project was designed to encourage students, families and interested citizens to record observations of the quality of their nighttime sky and share that data with others via the GWWSC Website. During the inaugural year, over 19,000 people from around the world went outside at night looking at specific constellations and “counting” the stars they saw as a means of measuring global light pollution (see Figure 1). Each observation is represented by a colored dot, with the darker dots representing darker skies (fewer lights at night) and the brighter dots representing brighter skies (more lights at night).

Figure 1: GWWSC Observations from around the World, October 2007.

The GWWSC is a useful project for teaching about the impact of artificial lighting on local environments and in raising awareness about the ongoing loss of people’s ability to study or simply enjoy the night sky in many parts of the world. Students can explore the different light sources in their community learning the relationship between science, technology and their society, as well as investigate the economic and environmental impacts of light on a local and global scale. The second annual GWWSC is just around the corner, October 20th – November 3rd, 2008!

GWWSC as a Citizen Science Project Currently, there is a high level of interest in the state of the environment by individuals of all ages and from all walks of life. Some issues that dominate current concern are global climate change, vanishing wilderness, and pollution – including light pollution. Citizen science allows all interested individuals to learn more about environmental matters while at the same time contributing to a better understanding of them. What do we mean by the term ‘citizen science?’ The Cornell Laboratory of Ornithology, a recognized leader in citizen science projects, defines it as “…a movement to explicitly engage the public in the process of science and the advancement of scientific knowledge.”

Interested individuals have the opportunity to get involved by making observations, and collecting and reporting data. Projects such as GWWSC, aptly named ‘citizen science’ projects, are generally designed to connect researchers with interested members of the public who collect

Page 2 The Great World Wide Star Count (www.windows.ucar.edu/starcount) © Copyright 2008 University Corporation for Atmospheric Research All Rights Reserved data or perform other scientific tasks following defined protocols. Citizen science projects, such as GWWSC, serve the dual purpose of education and outreach, and increasing scientific knowledge.

Participating in GWWSC The GWWSC was designed to engage citizens from around the world in recording observations of limiting magnitude of specific constellations (Cygnus in the Northern Hemisphere, Sagittarius in the Southern Hemisphere). The goals of GWWSC are to:

• Raise public awareness of sky quality issues worldwide • Collect global sky quality data • Encourage citizen science through a hands-on activity

Participation in GWWSC is open to anyone, anywhere, who can go outside in the early evening and look upwards. There are five simple steps to follow:

1. Determine which constellation to observe 2. Find that constellation about an hour after sunset 3. Match the nighttime sky with one of seven magnitude charts 4. Report observations using a simple online form 5. View the results

The night sky is divided into 88 constellations. Each constellation covers a specific area of the sky and includes groups of bright stars which appear close to each other when viewed from the Earth, but are really far apart in space. These groups of bright stars within the constellations are called Asterisms. For GWWSC, the first two steps are to identify the constellation you will observe in your night sky. For those who live in the Northern Hemisphere, the constellation to observe is Cygnus, the Swan, which includes the Northern Cross Asterism. For those that live in the Southern Hemisphere, the constellation to observe is Sagittarius, the Archer, which includes the Teapot asterism (see Figures 2 and 3).

Figure 2: Northern Hemisphere Constellation Cygnus / Northern Cross Asterism

Figure 3: Southern Hemisphere Constellation Sagittarius / Teapot Asterism

Step number three in GWWSC is to match your night sky with one of seven magnitude charts (see Figure 4). Magnitude is a term astronomers use to describe the brightness of an object. The magnitude scale for stars was invented by the ancient Greeks and based on the logarithmic scale. Brighter stars are given lower values and dimmer stars are given higher values. So, for example magnitude 1 stars are brighter than magnitude 7 stars, and thus can be seen even in light-polluted skies.

Figure 4: Four of the Seven Magnitude Charts for the Northern Hemisphere - Cygnus / Northern Cross Asterism

For the upcoming 2nd Annual GWWSC, participants can make observations anytime between the dates of Oct. 20th and November 3rd, 2008. Making more than one observation is encouraged! Simply go to a new location at least 1 km (0.6 miles) away from your initial observation location. It is quite interesting going to different locations and immediately seeing the difference in sky quality. For example, cross-sections of a city’s population density can be easily observed by transecting a city (i.e. following a main road into and out of a city, see Figure 5).

Figure 5: GWWSC 2007: Observations from Boulder County, Colorado. Transects shown enclosed in dashed red rectangles.

All observations are reported online through a simple form at http://www.windows.ucar.edu/citizen_science/starcount/report.html After the observation time period, all data received through the GWWSC Website will be available for download and analysis in a variety of formats (ESRI shapefiles, Google Map KMZ, Excel spreadsheet and comma-separated text files). Result maps and data sets from GWWSC 2007 are currently available online at http://www.windows.ucar.edu/citizen_science/starcount/results.html

GWWSC Results During the inaugural GWWSC in October 2007, the Web site received over 6600 observations from 64 countries on all seven continents and including all 50 U.S. States (see Figure 1 and Figure 6). The media coverage of this event demonstrated that GWWSC captured the public imagination and greatly exceeded initial expectations. News of the GWWSC was shared on Voice of America, National Public Radio, CNN Radio, Discovery Channel News, USA Today as well as many other newspapers, radio stations and online venues.

Figure 6: GWWSC 2007 Observations from the U.S.A.

Since light pollution is caused by the inefficient use of lights from human activities, it would seem reasonable to think that areas of higher population density would have brighter skies and thus more light pollution. The map of Boulder County, Colorado shown in Figure 5 illustrates this relationship. Two transects are clearly visible (enclosed in dashed red rectangles), one running east-west across the city of Boulder, and one running north-south through the town of Longmont. In the former, observations were made beginning in the mountains west of Boulder and continuing east across the county. More than 40 observations were recorded in this transect, and the changes to limiting magnitude correspond to variations in population density

The map in Figure 5 was generated using ESRI’s free ArcExplorer—Java Edition for Education (AEJEE), but educators can also use Google Earth to explore results, as shown in Figure 7. In this example, the background image is NASA’s “Earth City Lights” dataset (included in the current release of Google Earth), which provides a quick and easy way to compare submitted measurements to population density. .

Figure 7: GWWSC 2007: Observations from Boulder County, Colorado overlaid on NASA’s “Earth City Lights”.

Further understanding of GWWSC 2007 data can be found by exploring the bar graph in Figure 8, you can see that 384 observations were made with a limiting magnitude of 1 (brightest, most light-polluted skies) while only 245 were made with a limiting magnitude of 7 (darkest, least light-polluted skies). Figure 8 tells us that most observations were made under limiting magnitude 3 and 4 skies (mean = 3.7) which in turn tells us that most observations were taken in places with moderate light pollution. All the GWWSC datasets are available in Excel spreadsheet or text formats, providing students with the opportunity to perform their own statistical analyses.

Figure 8: Histogram of Magnitudes Reported during GWWSC 2007.

Page 7 The Great World Wide Star Count (www.windows.ucar.edu/starcount) © Copyright 2008 University Corporation for Atmospheric Research All Rights Reserved The citizen science approach and science content of GWWSC captured the interest of numerous astronomers around the world who volunteered to translate the activity guide. As a result of this interest, GWWSC materials have been translated into six languages. (The GWWSC Activity Guide is available in English, Spanish, Portuguese, Dutch, Italian, Romanian, and Chinese.) Clearly, GWWSC has interest from the international astronomy community, informal educators, and the general public. The success of the GWWSC can be attributed, in part, to the availability and accessibility of the Internet connecting with a widespread audience of interested citizens.

GWWSC in the Future In 2009, GWWSC (October 9-23, 2009) will participate in “Dark Skies are a Universal Resource,” one of seven primary US themes being developed for the International Year of Astronomy (IYA) in 2009. The goals of this theme are to raise the level of public knowledge about adverse impacts of excess artificial lighting on local environments; including issues related to human and animal health, security and the economy, and to help more people realize and appreciate the ongoing loss of a dark night sky as a natural resource for much of the world’s population.

Dark-skies awareness has been selected as one of a dozen major international “cornerstone” projects for IYA. According to the United Nations, 2008 is the first year in which more than half of the world’s population (3.3 billion people) lives in urban environments. As cities grow, so does their impact on the global environment, including excessive lighting. Dark-skies education efforts within IYA 2009 aim to heighten awareness of light pollution as a global problem, yet with a local solution.

The GWWSC brings families together to enjoy the night skies and become involved in science as well as raising the awareness of the impact artificial lighting has on our ability to see the stars. By participating in the GWWSC, participants are helping scientists studying light pollution, population patterns, and energy usage by providing valuable information that would have otherwise been impossible to obtain. People from all over the world are together assessing the quality of the night sky. Join us this October 20th – November 3rd, 2008 for the 2nd annual Great World Wide Star Count!

Figure 9: Great World Wide Star Count

For more information about GWWSC, visit www.windows.ucar.edu/starcount or send email to [email protected]

GWWSC is a Windows to the Universe Citizen Science Event. For more information visit: http://www.windows.ucar.edu/citizen_science/citizen_science.html