A "light relay" planned to coincide with the anniversary of Albert Einstein's death is facing opposition in the United States.
A leading UK science body has already opposed the plan, but a lack of support in the US could be more damaging because of the relay's route.
American dark skies campaigner Robert Gent said many astronomers and physicists felt the event, which involves shining lights skyward, would "set a bad precedent for protection of the night sky".
Mr Gent is president of The Astronomical League, a federation comprising 20,000 amateur astronomers.
He said: "Research in astronomy faces enough challenges without asking people to shoot light beams into the night."
Mr Gent, who is also on the board of the International Dark Sky Association, said he had "received a great deal of comments from others".
Albert Einstein died in 1955
"All say the same, and all seem to agree that this ring of light is not a good idea.
"We hope this project is dropped so that physicists, astronomers, environmentalists and others can truly stand together."
BBC News Online has previously reported that the UK-based Institute of Physics has withdrawn support for the relay because of negative public perception.
The relay will start in the US on 18 April next year, to mark the 50th anniversary of Albert Einstein's death in New Jersey.
From there, a planned 100,000 participants will flash lights skyward in a path around the world, with the US forming the relay's vital opening leg.
Ideas to appease astronomers include:
A flash of darkness preceding the relay
Excluding areas near observatories
Participants remove permanent light pollution sources
The event - dubbed "Physics Enlightens the World" - is part of the coming International Year of Physics.
The man behind the proposal is Dr Max Lippitsch, from the University of Graz, in Austria.
In a bid to appease light pollution concerns, he has incorporated a "flash of darkness" into the plan, which would involve switching off lights 10 minutes before the relay's passage.
People opposed to shining lights skyward have been invited to take part only in the "flash of darkness".
Other guidelines for the relay have been included to ensure light pollution is minimised, such as using only moderate light sources (like torches and car headlights).
According to the relay website, the event would show worldwide co-operation and raise public awareness of science.
Dr Lippitsch previously told BBC News Online the relay would "result in a tiny flash of light compared with the enormous light pollution produced steadily by our civilization".