Can you see
the stars at night? Next week, a
global star party kicks off, and you can join it from wherever you are on the
planet. March 8-21, people all over the world will walk outside and check out
the stars in the constellation, Orion, the hunter. It's a global star party
aimed at assessing light
pollution around the world.
Last year,
more than 18,000 people in 96 countries participated. They reported data from
all the continents except Antarctica. If you'd like to see the state of light
pollution on our planet, a global distribution map appears at the "Globe at Night" website [image]. As you
might expect, urban areas worldwide glow brightly at night. We city dwellers
see few stars on a typical evening. The glory of the night sky fades into the
glow of city lighting. For most people, the Milky Way is more familiar in the
grocery store candy aisle than in the sky. Living in the San Francisco Bay
Area, I experience this personally.
The global
star party aims to both assess light pollution, and to raise awareness of the
problem. Amateur and professional astronomers have long been aware of light
pollution. Both seek dark skies to observe. Unfortunately, such skies are
becoming rare.
The
spectacular discoveries made at Mt. Wilson in the early part of the 20th
century occurred when LA was a small city surrounded by orange groves. Today,
the telescopes there are of
limited use, and have been superseded by newer telescopes in less
light-polluted areas. Cities such as Tucson, AZ, require outdoor lighting that
emits limited wavelengths and lights the ground (not the sky) in order to protect the
surrounding professional observatories. Tucson's low-pressure sodium street
lighting glows in only a few spectral lines, and therefore can be filtered out
at the telescope. Likewise, the City of San Jose uses these same low-pressure
streetlights to help out Lick Observatory. The International Dark Sky Association
offers advice on the least light-polluting, most efficient methods for night
lighting. There's a good economic argument for low-pressure lights as well:
they save money. The lamps are less expensive, and cost less to operate. That's
a nice side benefit for reducing light pollution.
So how can
you participate? There are simple instructions at
the Globe at Night website. You'll find the tools to figure out where on Earth
you are: latitude and longitude. In case you're not familiar with Orion, there
are charts that help you pick out the constellation, and magnitude (stellar
brightness) charts that help you assess the visibility of stars at your
location. Once the observing campaign starts, the reporting page will activate,
and you can contribute your observations.
Everyone is
invited to participate. Individuals can simply use the online instructions. For
teachers, scout leaders and such, there's a 5-page teaching guide that includes
magnitude charts that can be downloaded and printed to assist young people and
families.
People
everywhere are concerned about energy consumption. The first step in changing
how we light the night will come from the evidence of nighttime light pollution.
Let's go get the data. I plan to check on Orion next week, and contribute data
from my light-polluted backyard. I invite you to participate in this virtual
star party, and help the world understand how we are squandering energy to
flood the night sky with light. Awareness is the first step toward social
change.
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