Astronomy
is about photons: collecting and analyzing photons of all energies reveals the
universe. When the professional astronomy community assembles, as it has here
in Hawaii, there's a high density of photon hunters. Ironically, the stars are
hardly visible outside our hotels. Like other high-rise cities, Honolulu floods the night sky with light. Worldwide, many people live in urban and
suburban centers under light polluted skies where the stars are barely visible.
Earlier
this year in March, a globe
spanning star party invited people to measure the light pollution in their
neighborhood skies as a part of "Globe at Night." Here at the AAS
meeting, a team of astronomers and educators from the National Optical
Astronomy Observatory reported on the preliminary data from the 2007 campaign.
So far, the 2007 Globe at Night campaign has logged almost double the number of
measurements at the 2006 campaign. It's an expanding project that engages the
public in collecting valuable data.
The idea of
citizen scientists counting the stars at night to assess light pollution
originated with campaigns in Greece and Austria. In 2006, several US organizations collaborated to initiate a US-based naked-eye star counting with "Globe at Night". The
standard, or classic program is to observe the constellation Orion, and compare
your sky with a set of star maps representing different levels of light
pollution. It's simple, produces reliable data, and engages people in many
places. This year, US reports were received from 49 of 50 states.
For 2007,
NOAO expanded the observing program with the addition of handheld digital
sky-brightness meters to measure sky glow, a.k.a., light pollution. Stephen
Pompea, an astronomer and manager of science education at NOAO said, "The
classic version is clearly gaining momentum. The digital mode, using
sky-brightness meters procured and distributed with special funding support
from the National Science Foundation, came together just in time and the early
results from this prototype project show great promise."
The new,
digital meters were shipped to teachers and students, amateur astronomers,
science centers and museums, and observatories in the US, Mexico, Chile—where NOAO operates and observatory—to collect and report measurements. More than
800 sets of digital data have been submitted, and the team anticipates further
reports. Sample city
maps of selected locales include Tucson, the home of NOAO, Washington DC, Richmond VA, Sonora Mexico, the island of Hawai'i and Las Vegas.
Connie
Walker, an astronomer and senior educator at NOAO, is lead coordinator for
Globe at Night. She explained "These initial maps are only a first look,
but the data show signs of good consistency and a gradient of bright to dark
measurements as one moves from the city center to outlying areas." Ultimately,
this sort of data can provide ground truth to satellite-based measurements of
night sky light
pollution.
With a smile,
Walker explained that people were very creative in the data collection
strategies. Teams of students took multiple measurements at the same site, and
averaged the data to submit it to Walker. In other cases, GPS-equipped teams
drove about their hometowns, shot the sky through the "moon roofs" of
their cars, and recorded the data with corresponding GPS position. Most all of
the 135 teams making digital sky
brightness measurements are now proposing an extended set of year-round
measurements. Observations through the night could record the changing patterns
of night lighting levels, or seasonal lighting changes that depend upon sports
arenas and other urban activities. There's also the possibility of discovering
dark sky oases amidst the light polluted skies, and obtaining the observations
that can be used to defend these dark spaces.
Walker looks forward to working with the
teams collecting digital data, and to expanding the program to include more
people and locations as we approach 2009, the International
Year of Astronomy (IYA). She's the US Chairperson for the Dark Skies
Working Group for IYA, and sees the 2007 campaign as a successful model for
creating a worldwide network of citizen scientists using both their eyes and
simple light meters to assess light pollution.
At a time
when we're all becoming conscious of the conspicuous consumption of energy,
assessing our light polluted skies is a first step toward better energy
management. And, as both an educator and photon hunter, I truly hope it is also
a step toward darker skies. It's not simply about better conditions for
astronomical observations; rather, it's about restoring the beauty of the night
sky for everyone.
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