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In the dark: Sky observations cast light on pollution

Southern Arizona contributes to 'Globe at Night' measurements

Globe at Night, which promotes the value of dark skies, set a record in 2010 with more than 17,800 measurements of night sky light pollution from people in 86 countries.

In the United States, 49 out of 50 states plus the District of Columbia contributed more than 10,900 measurements to "Globe at Night 2010."

Arizona, which benefits from tens of millions of dollars in related funding for astronomy and is home to the International Dark-Sky Association, led the way with more than 1,800 data points, including 1,000 from the greater Tucson area.

The worldwide total is 15 percent greater than the previous record, set last year during the International Year of Astronomy 2009 (IYA2009).

Globe at Night encourages people to observe the prominent constellation Orion at least once over a two-week period each March and compare the number of stars that are visible using their unaided eyes with a series of charts that show how Orion would appear in skies ranging from very dark to very bright skies.

The program teaches about the impact of excessive artificial lighting on local environments, and the ongoing loss of a dark night sky as a shared natural resource for much of the world's population.

Light pollution

Two-thirds of Americans cannot see the Milky Way from their backyard. Because of population growth, increasing light use and poorly designed fixtures, 99 percent live in areas that are considered light polluted, according to the National Parks Service.

Developed by the educational outreach group at the National Optical Astronomy Observatory (NOAO) in Tucson five years ago, Globe at Night has grown from a prototype project centered in Arizona and Chile to a global cornerstone program of the recently completed IYA2009.

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"A lot of the success in 2010 was due to the momentum from IYA2009," said Dr. Connie Walker, Globe at Night program manager at NOAO and leader of both the U.S. and international IYA2009 Dark-Skies Awareness working groups.

These groups have created a multifaceted set of ongoing citizen-science activities including Globe at Night and the Great World Wide Star Count, International Dark-Sky Week, dark-skies events in national parks, informational social media tools, a photography contest, a dark-skies teaching kit, and light-fixture swap outs.

Earth Hour

The international network spawned by IYA2009 also contributed major extra promotion for the wildly successful Earth Hour, during which hundreds of cities around the world annually turn down their lights for 60 minutes each March.

With active participation by more than 140 countries, IYA2009 "did a lot of good in getting the word out," Walker said. The previous Globe at Night record was 15,300 measurements from the March 2009 effort. Digital measurements with small handheld Sky-Quality Meters, which provide more precise observations than the seven-point visual scale, remained steady at about eight percent of the total in 2010.

"Locally, whenever I do a workshop, I mention Globe at Night as something [the participants] can be proud of, since it was created here" in Tucson, Walker added.

NOAO publicized Globe at Night in southern Arizona through its network of 200 Project ASTRO teachers and via a new partnership with the Cooper Center for Environmental Learning, which is which is owned by Tucson Unified School District and managed by the University of Arizona.

Project ASTRO was developed by the Astronomical Society of the Pacific as a way to connect middle school teachers interested in science with amateur and professional astronomers willing to make classroom visits to conduct hands-on activities, often supplemented with stargazing or solar viewing.

Robert Cratty is a member of the Sun City Vistoso Astronomy Club and a NOAO Project ASTRO astronomer who works with students at Coronado K-8 School, 3401 E. Wilds Rd. Cratty made presentations on Globe at Night to 5th and 7th grade classes at Coronado.

The students got visibly excited about Globe at Night during his demonstrations, Cratty said, especially when the mapping tools on the project website enabled them to zoom in and see their individual houses. "They got even more excited when the teachers told them they would get extra credit" for participating, he noted with a smile.

'Little dots'

Cratty subsequently monitored the real-time map of data points on the website and soon "little dots started popping up all over Catalina and Oro Valley." Cratty guessed that 30-40 kids from Coronado school participated in total, including one who inspired his father, a ranger at Catalina State Park, to take some unique measurements late at night in the park.

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In general, the students have gotten more interested in science and astronomy thanks to the hands-on nature of Project ASTRO and Globe at Night, Cratty said. "Several have said they want to be an astronomer when they grow up, and help save the world by searching for hazardous objects" to Earth, such as near-Earth asteroids and comets, he said.

Janine Bennette, an NOAO Project ASTRO teacher at Great Expectations Academy in Sahuarita, used Globe at Night in her 4th grade class at the charter school and with her afterschool astronomy club, called the Galactic Geckos.

"I love science and love to teach everything through science, so Globe at Night was a great fit," Bennette said. Each of the 22 students in her class took at least one measurement. "They got to enter real data," with many of them using their home computers, "so they loved it," she said.

Bennette also involved her 5th grade son in taking eight Sky-Quality Meter measurements dispersed around town, and loaned one of the digital devices to her school principal, Jeremy Topp, to enable him to take a measurement from his home in Tubac.

"He has really dark skies," said Bennette, adding that one student's measurements from their home in nearby Arivaca were "as dark as Kitt Peak [observatory], so that was exciting."

Beyond Project ASTRO, the NOAO group trained 18 teachers in the principles of Globe at Night through a partnership with the Cooper Center, which is on Trails End Road in the Tucson Mountains foothills. They also worked directly with about 40 K-12 classrooms of students who attended the center's two-day, two-night overnight program, which eagerly embraced the project as a tangible example of environmental science.

"There is definitely a strong environmental message with the topic of light pollution, as well as a sense of wonder about the night sky, so it really fit our needs," said Colin Waite, a program coordinator at the Cooper Center.

Many of the nearly 3,000 students who participated in the 2009-2010 school year emerged eager to "make changes in their lifestyle to use less energy and share these changes with the community, and light pollution is something that each student can have a huge impact on," Waite said. "The teachers were really excited to have something that the kids can use at home, in their schools, and in their communities."

The state of Arizona was followed by Michigan (1,200) and West Virginia (over 1000) in numbers of measurements taken in March. Internationally, Puerto Rico contributed over 1,000 measurements, followed by Poland (800), Romania and Chile (each over 600), the Czech Republic (400), Argentina (300), Hungary, Canada, the United Kingdom, and South Korea (200). China, with just under 200 measurements, Brazil, and Cuba made their first official measurements this year, the fifth year of the Globe at Night.

NOAO's Walker hopes to create a year-round Globe at Night program that would add elements of monthly and seasonal changes to the annual campaign each March, which will occur again in 2011.

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A map showing the extent of light pollution across the U.S. Credit: P. Cinzano, F. Falchi (University of Padova), C. D. Elvidge (NOAA National Geophysical Data Center, Boulder). Copyright Royal Astronomical Society. Reproduced from the Monthly Notices of the RAS by permission of Blackwell Science.

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