A Thing of the Past?
By Judy Rocchio,
NPS Air Quality Coordinator and
GGNRA Natural Resources Management
From Golden Gate National Recreation Area
stars awaken a certain reverence, because though always present, they are inaccessible."
Ralph Waldo Emerson
A satellite image of the United States reveals areas with the highest levels of light pollution. Each night, the sky is washed with a flood of artificial light, which not only restricts astronomers' ability to study the universe, but may also have negative biological consequences for Earth's plants and animals. NOAA
stars of the Milky Way have fascinated humans for millenia. Ancient mariners guided
everything from outriggers to sailing ships using this galactical road map. But
it is quite possible that future generations of children will not be able to see
the galaxy they live in, or the wondrous canopy of stars that has inspired poets,
philosophers, and dreamers for centuries. The flood of artificial light that washes
the stars from the sky today has left one in five human beings unable to see the
Milky Way at night, according to a new study of the global effects of light pollution.
A 2001 global satellite study conducted by scientists at the University of Padua,
Italy, and the U.S. National Oceanic and Atmospheric Administration (NOAA) measured
for the first time how light degrades the view of stars in specific places around
"The rapid increase in light pollution is one
of the most dramatic changes occurring in our natural environment," noted the
Royal Astronomical Society, which published the study. The survey shows that truly
dark, starry skies are unavailable to two-thirds of the world's population, including
99 percent of people in the continental United States and Western Europe. The
report describes regions of the world where true night never occurs because it
is blocked by lights from cities and towns. In night's darkest places, far from
city lights, about 2,000 stars are typically visible. In major cities, that number
shrinks to a few dozen at most.
Scientists have now discovered that darkness optimizes health.
Only when it's really dark can the human body produce the hormone melatonin. Melatonin
fights diseases, including breast and prostate cancer. "It turns off the cancer
cells from growing," says Joan Roberts, a photobiologist.
if there's even a little light around your bed at night, melatonin production
switches off. "So there may be this natural way that Mother Nature has given us,
that is, dark night to keep certain cancers under control," Roberts says. Nature
needs darkness, too; the immune systems of animals grow weak when they're exposed
to artificial light at night.
A Recoverable Resource
some natural resources that
are unrecoverable once lost‹species extinction
or clear-cut old growth forests‹night sky darkness is potentially recoverable
in many places. Lights that glare into the sky and wipe out the stars can be shielded
and focused with reflectors to make them more efficient and to reduce light trespass.
Or, lights can simply be turned off.
Pointing light where
it doesn't need to go also wastes energy. For example,
by "going dark" nightly,
some office buildings and school systems are saving as much as $1 million a year
in energy costs. Police report that darkness is often safer, partly because neighbors
soon learn to alert police if they see lights in a building.
National Park Service policy dictates that parks must, to the
extent possible, manage to preserve, protect, or enhance the night skies. This
requires implementation of best management practices within their boundaries and
working outside the park with local communities to promote night-lighting ordinances.
Here in the Golden Gate National Parks, we are implementing
sound lighting practices by avoiding and eliminating unnecessary night lighting,
and by using shielded light fixtures and low-intensity lights. Nationwide, the
NPS will be partnering with local groups to develop measures to reduce light trespass
from sources outside the parks. With your help, we can bring starry nights back
to our parks.
Light pollution is not just a problem in North America, as can be seen in this satellite image of the world; industrialized and/or heavily populated areas can be easily identified from a long way up! NOAA