WESTFORD — Tim Brothers can see dwarf planets and asteroids from the MIT Wallace Astrophysical Observatory, but not as often as he could a few years ago, before nearby development started clouding his view with light pollution.

When the MIT opened the observatory in the 1971, it was to view the sky from a dark area, away from the bright, urban lights of Cambridge and Boston. But within the last few years, the amount of development in and around Westford has increased as land once known for farming fills with housing developments, shopping plazas and car dealerships.

The difference that has created in astronomical work has been immense, said Brothers, the observatory manager.

What causes light pollution are lights themselves — high-duty halogen or sodium bulbs, and even blue LED lights, that flood the sky with light and make it challenging to view darker objects farther off in space.

In the observatory’s past, and to some degree at the beginning of Brothers’ tenure at the observatory seven years ago, “there were not shopping plazas, there were not car dealerships, there were not movie theaters going in, there were not major housing developments,” he said. “People didn’t put spotlights on their houses, and there wasn’t the obsession with putting giant 1,000- or 2,000-watt fluorescent bulbs on every doorway so that people could see their doorways, so that’s changed.”

What Brothers and students study at the observatory, which is a part of the MIT Department of Earth, Atmospheric and Planetary Sciences, is Pluto and beyond. Their research is on objects that follow the path of the sun, east to west, which coincidentally is also the direction that development is occurring, from Lowell to Chelmsford, to Westford and Littleton.

Brothers said he is not anti-development, but is working to educate developers and others about measures that help reduce light pollution and preserve dark skies for stargazing and research. This also includes working with policy makers, and the hope of getting a state or federal guideline passed, he said.

“I’ve seen it change, and by change I mean I can literally see the effects in our data where objects are disappearing into the background,” Brothers said.

When he began at the observatory, Cornerstone Square wasn’t built yet. As it was constructed, and now with completion, Brothers has observed a swath of sky light in that area, making some objects disappear from view.

“It makes it harder for us to do our job,” he said. “It means that we have to have other people observe for us, or we have to send students and researchers elsewhere.”

Robert Walker, the developer of Cornerstone Square, could not be reached for comment.

“We sort of missed the boat with some of the Westford development,” Brothers said. But, “We can turn back the clock.”

Buying LED lights that are a warmer tone, which is 3,000 Kelvins or below in the color temperature scale of lighting, won’t be as harsh on the sky or on people’s eyes, according to Brothers and research studies. People can also buy lighting with a shield, or light fixtures that face the ground, so that unnecessary light does not flood the sky. And of course, turning lights off when not needed makes a difference.

Such measures can help bring down the amount of light fogging up vision, making the sky darker, the way it is in less-developed areas like Tyngsboro and Dunstable.

There are a host of reasons to invest in such lighting, Brothers said. Not only does LED lighting save money through energy efficiency, but warmer lighting is less harsh on both human eyes and on animals. Nocturnal animals can become confused when there is excess lighting during the night, Brothers said. Light pollution affects the migration of animals, and the melatonin production of people.

In the Westford zoning bylaws, the section on Major Commercial Projects has instructions to avoid light pollution, conserve energy, and preserve aesthetic qualities. According to town documents, lights outside the police department, which are on 24 hours per day, face the ground so not to pollute the sky.

As The Point on 495 started emerging in Littleton, Brothers reached out to developer Sam Park to discuss avoiding sky pollution.

While not every light in the plaza is on the warmer scale, a majority of the parking lot lighting faces the ground, Park said in a phone interview.

“I do know all of our parking lot lighting are shielded,” Park said. “We’re always eager to make sure we don’t interfere with other people’s use of the sky.”

Brothers plans to keep calling and emailing developers to spread the message about stopping light pollution. He is also planning to reach out to lawmakers about supporting a state or federal bill to give developers an ordinance to follow. Bill S.2159, “An Act improving outdoor lighting and increasing dark-sky visibility,” was reported favorably by the committee on Telecommunications, Utilities and Energy and referred to the committee on Senate Ways and Means. The bill is sponsored in part by state Sen. Jamie Eldridge, D-Acton. Brothers said he plans to reach out to legislators soon to help promote the cause.

“Just in general, minimize the light,” Brothers said. “If we can change a little bit, it helps a lot.”

To learn more about sky pollution, visit the International Dark Sky Association website, darksky.org.

Follow Melissa Hanson on Twitter and Tout @Melissa__Hanson.

Four ways to reduce light pollution:

* Only have lights on when needed.

* Minimize blue-light emissions.

* Have lights shielded and pointed downward.

* Only light areas that need it.

Source: International Dark-Sky Association