Saving the Night Sky: Dark skies and light pollution

HILLSDALE — Susan P. Bachelder, a resident of Egremont, Massachusetts, and member of DarkSky International, gave a presentation “Saving the Night Sky: Dark Skies and Light Pollution” at the Roeliff Jansen Community Library on Thursday, May 2.

Bachelder began the discussion by reminding the audience to Save the Date of Aug. 12 when the Perseids meteor shower will occur. Bachelder noted that meteors are best observed after midnight, when the they are moving in the same direction as the Earth’s rotation.

Bachelder has been a member of DarkSky International (DarkSky.org) for more than 10 years. DarkSky, originally a small Arizona based nonprofit founded in 1988, has worked for more than 30 years to restore the night-time environment and protect communities and wildlife from light pollution.

Light pollution, defined as “the inappropriate or excessive use of outside artificial light,” is having serious environmental consequences for humans, wildlife and our climate.

DarkSky International is now comprised of more than 70 chapters worldwide. DarkSky International works to certify and help conserve starry sky parks, communities and other outdoor places. The group also certifies commercial, industrial and residential outdoor lighting with an aim to reduce light pollution by working with communities, governments and professionals to prioritize quality low impact, outdoor lighting.

The talk was comprised of two parts. First, the short film “Dark Sacred Night,” a 15 -minute overview created by filmmaker Jared Flesher for the Princeton University Department of Sustainability. The film features astrophysicist Gaspar Bakos and his quest to reduce light pollution by raising awareness of the dangers of light pollution on the Earth and its inhabitants.

Filmed on location at Princeton University and the Las Campanas Observatory in the southern reaches of Chile’s Atacama Desert, Bakos speaks of the necessity to direct lighting downward to protect the night sky.

According to Bakos, “80% of the U.S. has lost the vision of the Milky Way and light pollution has increased 50% over the last 25 years…due to the conversion to LED lighting.” While it has been observed that light pollution threatens many animal species, from migrating birds to hatchling turtles, the negative impact on humans is less well documented.

The interruption of natural sleep patterns in humans can easily be linked to light pollution. Bakos stated it has only been within the last 20 years that the effects of light pollution upon the Earth have only been studied. A 2016 study conducted on “Artificial Light at Night and Cancer” concluded “artificial light at night is significantly correlated for all forms of cancer including lung, breast, colorectal and prostate cancers individually.”

A 2020 study linked the “association of outdoor artificial lighting at night with mental disorders, including mood and anxiety disorders in adolescents.”

According to Bakos, 40% of outside lighting is wasted. Lights point up into the sky, wasting about $3 billion per year by converting carbon into photons. That is the equivalent of 21 million tons of carbon dioxide emitted every year. Bakos stated that light pollution goes unchallenged because the effects are generated far away from the source therefore there is a failure to connect the cause to the outcome.

According to Bakos, the solution to light pollution is simple.

— Exterior lighting should be useful, installed only when and where it is need.

— Lights should be shielded so they only shine down upon the ground.

—Lights should be no brighter than necessary and when possible controlled by dimmers, timers or motion sensors.

— Mostly importantly, outdoor lighting should be composed of warm colors, especially red light, rather the current use of harmful blue wavelength lights.

The second part of the talk featured Bachelder’s discussion of the “Constellations of the Northern Summer Sky.” . Bachelder started by asking who in the audience had observed the recent solar eclipse on April 8. An audience member stated that he observed the eclipse “but hadn’t travelled to see it.” Bachelder responded, “Luckily in this part of the country the eclipse was 97% observable so there was no need to go anywhere.”

Bachelder, an advocate of viewing the night sky with the naked eye, pointed to the constellations observable in our region and demonstrated how to navigate from The Big Dipper (observable in this region all year long) arcing down to the Constellation of Bootes (roughly the shape of an ice cream cone) to get one oriented in the summer night sky.

Bachelder explained that although we use the term “Constellation” as a standard, many star patterns are Asterisms. Asterisms are a star pattern that makes up part of a constellation or that include more than one constellation. An example of an asterism is the Big Dipper which is part of the constellation Ursa Major.

Bachelder, a classics major, is currently studying Persian star charts. She explained people in the audience are most likely familiar with Hellenic astronomy and the constellations named by the ancient Greeks (and their Latin counterparts). She introduced participants to the Persian named constellation, Al Thuraya, Al Thurya is a bright constellation, clearly visible to the human eye in the summer night sky, and is represented by a woman with outstretched arms.

Bachelder ended her presentation briefly discussing the need for governmental agencies to regulate exterior lighting. Currently, exterior lighting is rarely if ever, regulated by site plan.

Dark Sky Backpack

Tamara Gaskell, Director of Roeliff Jansen, located at 9091 Route 22 in Hillsdale, introduced a new acquisition to the library: The Dark Sky Explorer Backpack. The backpack, donated by the Mid-Hudson Chapter Adirondack Mountain Club (www.midhudsonadk.org) contains everything needed for exploring the night sky. The backpack, which can be checked out for 21 days by Mid-Hudson library card holders, contains: sky quality meter in pouch and plastic case with Globe at night card; night vision LED flashlight; night sky planisphere; book Let There Be Light, book Lights Out; and instructions and brochures.