Reflect Orbital's space mirrors could brighten night sky 40 times full moon, study finds

August 21, 2026 at 02:00 PM2 min

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Reflect Orbital's planned sunlight-reflecting satellites could brighten the night sky far beyond their target areas, a new study finds. A single satellite would appear about 40 times brighter than the full moon within a five-kilometer beam zone, and as bright as the full moon up to 14 kilometers away. The company plans to launch a test satellite later this year, even as astronomers warn the project is incompatible with dark skies.

Key Facts

Reflect Orbital plans to launch a test satellite called Eärendil-1 later this year with an 18-by-18-meter mirror.
The company aims to eventually operate up to 50,000 satellites measuring 54 by 54 meters to reflect sunlight to Earth on demand.
A single Reflect Orbital satellite would appear about 40 times brighter than the full moon within a five-kilometer target area, according to a study accepted by Astrophysical Journal Letters.
Combining beams from 400 satellites would produce light as bright as 10,000 full moons within the five-kilometer area, or 2.4% as bright as the sun.
The Federal Communications Commission approved the Eärendil-1 launch in July.

Satellite Brightness Calculations

Miroslav Kocifaj of the Slovak Academy of Sciences and colleagues modeled how light from the satellites would scatter in the atmosphere. They found that within the intended five-kilometer-wide beam area, a single satellite would appear about 40 times brighter than the full moon. At distances up to 14 kilometers from the beam center, the satellite would still appear as bright as the full moon. Combining beams from 400 satellites would create light as bright as 10,000 full moons within the five-kilometer area, or 2.4% as bright as the sun. Even 80 kilometers away, the combined beam would be visible as a glow above the horizon, Kocifaj said.

Astronomer and Company Reactions

Samantha Lawler, an astronomer at the University of Regina, said the project is incompatible with astronomy and preserving dark skies. Kocifaj stated that deploying these mirrors would be seriously damaging for astronomy and the nighttime environment, with damage extending far beyond the target area. Olivier Hainaut of the European Southern Observatory said the results are not surprising but useful, noting the authors are skilled at this type of modeling. Hainaut's earlier modeling found Reflect Orbital's beams could brighten the sky up to 300% worldwide. Reflect Orbital CEO Ben Nowack disagreed with the findings, saying some assumptions in the paper are simply inaccurate.