Home Science Astronomers Raise Concerns Over Light Pollution from Massive New Satellite

Astronomers Raise Concerns Over Light Pollution from Massive New Satellite

The night sky, a canvas of stars, planets, and other celestial wonders, is now overshadowed by an unexpected bright object: a communications satellite named BlueWalker 3. This satellite, which bears a resemblance to a Tetris block, is among the brightest objects visible from Earth, rivaling the luminosity of some of the brightest stars in our sky.

Key Highlights:

  • BlueWalker 3, at its peak brightness, is comparable to Procyon and Achernar, two of the night’s brightest stars.
  • The satellite’s appearance is not just a curiosity; it poses significant challenges to ground-based astronomy.
  • Large constellations of bright artificial satellites in low Earth orbit (LEO) can interfere with astronomical observations.
  • The aerospace industry’s trend towards launching larger and brighter satellites is on the rise.
  • Radio frequencies used by BlueWalker 3 could potentially interfere with radio astronomy.

The BlueWalker 3 satellite, once it unfolded its 64m^2 array, is visible in both dark and urban skies. However, in urban settings, its visibility is limited to when the satellite passes directly overhead. Dr. Jeremy Tregloan-Reed, a co-author of the study from the Universidad de Atacama in Chile, emphasized that the satellite’s presence is more than just an intriguing sight.

Challenges to Astronomy:

Large constellations of bright artificial satellites in LEO present significant obstacles for astronomers. A major concern is the large reflective brightness of these satellites. When such a satellite crosses a telescope’s detector, it leaves a streak that can be challenging, if not impossible, to remove. This means that the data in the affected pixels might be irretrievable. Moreover, space-based astronomy, such as observations by the Hubble telescope, has been increasingly affected by streaks from satellites like Starlink.

Growing Trend and Concerns:

Despite the challenges posed by these satellites, the aerospace industry’s trend towards launching increasingly larger and brighter satellites continues. BlueWalker 3, constructed by AST SpaceMobile, is just a precursor to a planned constellation of satellites dubbed “Bluebirds.” Another pressing concern is the radio frequencies employed by BlueWalker 3. These frequencies are alarmingly close to those used for radio astronomy, raising the possibility of interference that could hinder scientists’ ability to study the universe.

A collaborative effort between amateur and professional astronomers from various countries, including Chile, the US, Mexico, New Zealand, the Netherlands, and Morocco, sought to understand the impact of BlueWalker 3, the largest commercial communications array in LEO. The satellite, launched in September of the previous year, unveiled a vast surface area that reflected sunlight once in space. Dr. Tregloan-Reed pointed out that the brightness of an object also depends on its distance from Earth. Satellites in LEO, like BlueWalker 3, appear much brighter than their geostationary counterparts.


The increasing brightness of the night sky due to artificial objects is a growing concern. Earlier this year, researchers advocated for a cap on the number of low-altitude satellites to minimize light pollution and ensure the night sky remains a source of wonder and scientific exploration. The introduction of satellites like BlueWalker 3 underscores the urgent need for regulations to preserve our ancient relationship with the cosmos.