Massive space mirrors could be 40 times brighter than the full moon, astronomers warn. 'It will be worse than big cities like London'

Key Points:

• A study found that each sun-reflecting mirror proposed by Reflect Orbital would appear 40 times brighter than the full moon to observers within its beam, causing severe light pollution that would erase star visibility and create a twilight-like sky.
• Reflect Orbital received FCC approval to launch a demonstration satellite with a 60x60 feet mirror to test reflecting sunlight to Earth for solar power and disaster illumination, but plans to deploy 40,000 larger mirrors have sparked widespread objections from astronomers, environmentalists, and pilots.
• Researchers calculated that operational mirrors, sized 174x174 feet, would create a 3.4-mile-wide beam so bright it would brighten the sky over a 21-mile radius beyond full moonlight levels, with combined beams from hundreds of mirrors potentially producing near daytime brightness visible up to 50 miles away.
• Reflect Orbital disputes the study’s assumptions, claiming most mirrors will serve remote locations and remain below naked-eye visibility when inactive, but critics highlight the lack of technical data backing these assertions and warn of significant light pollution impacts on towns and natural environments.
• The FCC stated that impacts on optical astronomy are outside its review scope, and satellite projects remain exempt from environmental assessments under NEPA, despite receiving nearly 1,900 objections concerning Reflect Orbital’s satellite mirror plans.