Greenhouse light pollution affecting work at the Hallam Observatory in Comber

Members of the Windsor Chapter of the Royal Astronomical Society of Canada are hoping to get the amount of light coming from greenhouses in Essex County reduced.

The light pollution at night has interfered with their ability to use the Hallam Observatory near Comber, Ont.

"On the worst night here from due east to due west and straight overhead — that entire part of the sky, half the sky essentially is virtually starless," said past president Randy Groundwater.

Society member Dan Taylor said the light pollution is also hampering research work.

"I was a member of a scientific association in the United States that collected information on specific stars, now because of the light pollution it's much more difficult to do that kind of work," said Taylor, who was instrumental in getting Point Pelee National Park designated a dark-sky preserve.

Groundwater said doing that around the observatory isn't possible because the area is largely agricultural.

The greenhouse growers are fighting a Leamington bylaw limiting the light pollution and are due in court this summer.

"I think we can come to some kind of a middle ground," Ontario Vegetable Greenhouse Growers executive director Joe Sbrocchi told CBC News on Monday.

Sbrocchi said sealing up the greenhouse to prevent all light escaping isn't doable, but believes greenhouse growers can reduce the amount of light being released by 90 per cent or more.

"The problem there is that if you don't allow a certain amount of heat and humidity at different times of the year to escape, you'll cook your crop," he said. "We need to protect crops."

Cooler LED lights may be an option, Sbrocchi said, although those lights still cause some heat that would need to be released.

"The the concern is really in the shoulder seasons, going into the cold and coming out of the cold," he said. "And then, of course, the days get longer as well."

"But but in those periods of time when you think that the temperature is going to be one thing and then it's 15 degrees more, those plants are ... throwing off heat like you wouldn't believe so."

"It would require [the greenhouses] to be open up to 10 per cent."

Not every day requires a 10-per-cent opening, however, and on colder days, the greenhouse curtains — which are installed along a greenhouse's ceiling — could be nearly completely closed.

There are other challenges, as well. Installing curtains in older greenhouses with lower ceilings is very difficult, Sbrocchi said.

• Leamington taking legal action against greenhouse lights

Groundwater said light pollution is also detrimental to wildlife and can disrupt circadian rhythms.

He said the society doesn't want to move the observatory because part of its mandate is public education locally. He said it's getting more difficult to find areas where there isn't light pollution, anyway.

Groundwater said if the light pollution continues to get worse, the observatory will likely concentrate on observing the sun, moon and bright planets.

"The proliferation of the greenhouse industry, while has been great for the local economy, has had detrimental effects on the sky quality at night."