A view of the Earth's night lights from space.
Credit: Globe at Night.
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 Today, the telescopes there are of limited use, and have been superseded by newer telescopes in less light-polluted areas.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.
- VIDEO: Welcome to the Universe
- Image of the Day: Dark Night, Bright Galaxy
- Spacewatch Friday - Disappearing Stars: How 2,500 Points of Light have Dwindled to 15
- Czech Republic Enacts World's First National Light Pollution Law
- Dark Sky Movement: Fighting to Save Our View of Heaven
- ZOOM View: Get up close with the Orion Nebula
- DOWNLOAD: Welcome to Astronomy: A Guide to Getting Started (PDF)
- Constellation Pronunciation Guide
- All About Stars