CHARLESTOWN — Scott MacNeill was in Ninigret Park, his telescope trained on the comet “Ison,” when he saw something he had never seen before: a celestial phenomenon called “zodiacal light.” After several decades of being obscured by light pollution, the feature was visible again, thanks to the town’s “dark sky” ordinance.
At first, MacNeill, an astronomer and the assistant director of the Frosty Drew observatory, didn’t believe what he was seeing. The cone of light, which he initially thought was light pollution, turned out to be a faint, white glow that astronomers at the observatory hadn’t glimpsed in recent memory.
“I was sitting back for a minute, just looking at the sky, and I said ‘wait a minute. This is the southeast, and to the southeast is the ocean. What is coming up in the southeast?’ And then I noticed the cone. And I’m like ‘no way. That can’t be zodiacal light.’ I’ve heard so many stories about the days of old at Frosty Drew when you used to see zodiacal light here,” he said.
Zodiacal light is the product of a cloud of dust particles, asteroid fragments, and comets passing through the solar system and coalescing along the plane of the solar system, known as the ecliptic.
It appears as a glow extending up from the horizon, and it is so faint that any light pollution will render it invisible.
“To see it in New England, period, is amazing,” MacNeill said. “Zodiacal light is a common marker for the quality of a dark sky location.”
MacNeill credits Charlestown’s dark sky ordinance with reducing light pollution to the point where zodiacal light can be seen again. The ordinance, adopted in October 2012, regulates commercial outdoor lighting in order to improve the town’s dark sky for star-gazers, and to protect residents, wildlife and light-sensitive plants from the effects of light pollution.
One of the provisions of the ordinance requires that new lighting fixtures be designed to focus downward so light does not radiate up into the sky. Lighting installed before the ordinance was passed is exempt from the new regulations.
Ruth Platner, chairwoman of the town’s Planning Commission and a proponent of the ordinance, acknowledged that it had faced some opposition.
“The ordinance had tremendous support and some organized resistance, and like many things in Charlestown, it got slowed down by politics, but ultimately it did pass with some compromises. I believe as time passes that more and more people will come to see that we made a positive step when the Town Council passed the ordinance in 2012,” she said.
Building and Zoning Official Joe Warner explained that after the ordinance passed, two major sources of light pollution near the observatory were modified so they would be less polluting.
“At Ninigret Wildlife Refuge, some of the pole lights were changed to dark sky compliant lighting. The Charlestown Ambulance barn also replaced their lights with dark sky compliant lights,” he said.
Warner noted that while the ordinance applies only to commercial outdoor lighting, the town has encouraged residential property owners to switch their outdoor lighting, too.
The town includes a pamphlet on dark sky lighting with each building permit it issues, and Warner said homeowners have been receptive to the changes. Warner attributed Charlestown’s darker skies not to a single change, but rather, a town-wide effort.
“It’s not like we tell them to do it. They don’t have to, but it seems that a lot of people are. The word has gotten out,” he said.
Town Council President Thomas Gentz said the ordinance had enhanced the quality of life in the town.
“I’m happy that it has been passed and that it’s in place and I think Charlestown will continue to be an attractive community because of our dark skies,” he said.
Charlestown has been recognized as one of the only dark spots on the New England coast — a rare treat for people who enjoy looking at the night sky.
“In Charlestown at night, the skies are dark and the stars are spectacular,” Platner said. “This is a natural resource that we sadly have a monopoly on. Charlestown is the last dark sky area along much of the Eastern Seaboard. From Florida into Maine, the seacoast is a band of light except for an area centered on Charlestown.”
MacNeill agrees that Charlestown’s night skies are exceptionally dark, rivaled only by those of Nantucket.
“We’re always going back and forth with Nantucket,” he said. “They have a few observatories. They claim that they have the darkest skies.”
Those wishing to see the constellations in the dark sky for themselves can bring their own telescopes to the Frosty Drew observatory in Ninigret Park, and the public is welcome to visit and look through the observatory’s high powered telescope every Friday evening. Zodiacal light is visible to the naked eye and can be seen just before dawn in the East and after sunset in the West. While people living in less developed countries take it for granted, zodiacal light is rarely visible in this densely populated part of the country, MacNeill said.
“I would never expect to see it in Rhode Island,” he said. “That really blows my mind.”