The days are glorious in Acadia National Park, but so are the star-filled nights.

Acadia, with the darkest skies along the US eastern seaboard, is where the thousands of stars making up the Milky Way can be seen, something that two-thirds of US residents can’t view at home because of city lights.

All you need to do is look up on a dark, clear night, and you’ll be starstruck in Acadia, as our nieces were in recent visits, Stacey at Thunder Hole, and Sharon and Michelle at the ranger-led Stars Over Sand Beach program.

To celebrate in celestial style, Acadia National Park, the Friends of Acadia, Schoodic Institute, local chambers of commerce and more than a dozen businesses and organizations, are holding one big party Sept. 25 – Sept. 29, the 6th annual Acadia Night Sky Festival.

Among the more than 30 events planned: Star parties, night hikes, kid-friendly activities, a boat cruise, movies and scientific and literary presentations, and bioluminescent canoe paddles.

But it’s not just another festival to help boost the Downeast Maine economy in between the busy summer and peak foliage seasons.

It’s also an important reminder of how dark skies are a dwindling resource around the world, affecting astronomy, ecosystems and even human circadian rhythms. And it helps highlight the estimated $2 billion a year being wasted with unnecessary lighting in the US alone, a statistic publicized by the International Dark-Sky Association (IDA), a non-profit founded in 1988 to reduce light pollution.

Dark skies hard to find around the world

In fact, the idea for the Acadia Night Sky Festival resulted from a Bar Harbor Conservation Commission summit to minimize light pollution and a local ordinance.

In national parks across the country, and at sites internationally, preserving night skies has become a lofty goal.

To encourage protection of natural night, the IDA has even established a rigorous certification process for being named an International Dark Sky Park, with a Gold, Silver and Bronze tier.

Only 12 parks around the world have received the IDA’s Gold tier, where the skies are darkest. National Park Service-run sites in the US with the highest designation so far:

– Natural Bridges National Monument, Utah

– Big Bend National Park, Texas

– Death Valley National Park, California

– Chaco Culture National Historical Park, New Mexico

IDA’s Web site doesn’t list Acadia, or say whether or not the park has applied for certification in the Gold, Silver or Bronze tier. The last application deadline date this year is Nov. 24.

The National Park Service also has an effort to protect night skies, through a Natural Sounds and Night Skies Division. And parks around the country have at various times hosted astronomy and night-sky programs or festivals, from the Badlands to Zion, not just Acadia.

Reasons and efforts to protect natural night

While programs and festivals help people appreciate dark skies where they exist, the IDA aims to push the agenda further, not only with its rigorous International Dark Sky Park certification, but also with its legislative efforts, night-sky-friendly light fixture standards and educational materials (including a newsletter for kids with jokes and puzzles).

Among the legislative accomplishments listed on the IDA Web site: Recent passage of state dark-sky laws in New Hampshire and Hawaii, and national legislation in Italy.

And among the reasons night skies matter, as described by the IDA in some of its educational materials:

– Tens of thousands of migrating birds die annually in collisions with buildings left lit at night

– Newly hatched marine turtles may be unable to find the sea because of distracting night light

– Too much artificial light at night disrupts human circadian rhythms and has been linked to sleep disorders, depression and other health issues (the American Medical Association issued a report on the health implications of light at night in 2012)

– The ability to study the stars from observatories, such as the one atop Mt. Wilson in California, is being affected by light pollution

IDA, an 11,000-member strong organization with 58 chapters (including Maine) in 16 countries, was founded by Dr. David Crawford, a professional astronomer, and Dr. Timothy Hunter, a physician and amateur astronomer, both from Arizona.

The IDA’s idea, as described on its Web site, is simple: “Light what you need, when you need it.”

But such a simple idea can help prevent an immense, multigenerational loss, as its Web site says:

“A lost view of the stars extinguishes a connection with the natural world and blinds us to one of the most splendid wonders in the universe. Children who grow up without the experience of a starry night miss invaluable opportunities to speculate about larger questions and to learn about the environment and larger world.”

Something to ponder the next time you look up at the stars over Acadia National Park.