Amazon's internet-beaming satellites, though not visible to the naked eye, pose a measurable threat to ground- and space-based astronomical research, according to a pre-peer-reviewed study.
The satellites exceed the International Astronomical Union's (IAU) brightness limit for harmless coexistence with astronomical research, orbiting at 391 miles (630 km) with an average apparent magnitude of 6.28. This brightness makes them visible in 25% of observations without telescopes.
Anthony Mallama, lead author of the study, stated: "Bright satellites are particularly troublesome for large-scale astronomical surveys... and can also interfere with orbiting observatories like the Hubble Space Telescope."
The research, posted on Arxiv on January 12, 2025, analyzed nearly 2,000 satellite observations but has not yet undergone peer review. Amazon has since 2023 implemented design changes to reduce satellite reflectivity, including mirror-like undersides and component orientation adjustments.
John Barentine noted: "Amazon Leo is an instance in which the operator established a dialogue with astronomers early in the design phase... this effort has yielded some success." However, Amazon's plan to lower future satellites to 366 miles (590 km) will increase their brightness further.
The study highlights the need for continued collaboration between satellite operators and the astronomical community to mitigate these impacts.