A collective of astronomers plans to petition the International Court of Justice (ICJ) to control the growing number of satellites in Earth's orbit. This initiative aims to define the responsibilities of countries regarding damage caused to the night sky and astronomy.
The mobilization is coordinated by the Outer Space Institute and intends to present this issue to the United Nations (UN). The movement gained momentum due to the plans of corporations such as SpaceX, Google, and Starcloud, which intend to establish vast satellite networks to provide internet and computing services.
The campaign began in 2023, motivated by the effects of internet megaconstellations, such as Starlink. In the last twelve months, the concern has grown with the space data center projects disclosed by aerospace and technology companies.
Another point of attention is Reflect Orbital. In July, the U.S. Federal Communications Commission (FCC) granted the company permission to launch the experimental satellite Eärendil-1, which uses mirrors to reflect sunlight onto photovoltaic plants after sunset. This project could evolve into a constellation of tens of thousands of these mirrors, which critics warn could intensify celestial brightness, making astronomical observations unfeasible in several regions.
Among the concerns raised by researchers, it is highlighted that astronomers have already tried to address the issue with the United Nations Committee on the Peaceful Uses of Outer Space (COPUOS), but a suggestion to create a specialized group on light pollution did not achieve unanimity.
Aaron Boley, an astronomer at the University of British Columbia and co-director of the Outer Space Institute, detailed the difficulty of the process. He commented that 'getting something approved by COPUOS can be very, very difficult because COPUOS works by consensus. Consensus is very hard to achieve, and therefore, many initiatives end up paralyzed.'
In the context of the UN General Assembly, the procedure would be different. A single country would have the prerogative to submit a resolution requesting an advisory opinion from the ICJ, which would require the simple majority support of the present and voting States. Although this opinion is not legally binding, it can influence disputes and proceedings at the national level.
Robin J. Frank, an expert in international law and politics and former legal advisor to NASA, emphasized this potential. She stated: 'Using the advisory opinion of the ICJ in domestic legal proceedings carries substantial weight.'
The adopted strategy serves as a model for the case of Vanuatu. In 2023, this small Pacific nation obtained international support to request an opinion from the ICJ on the obligations of countries regarding climate change, whose opinion was published in July 2025. Since then, this understanding has been applied by environmental groups in local litigation, such as in France, where organizations invoked the opinion against TotalEnergies, demanding the disclosure of climate risks linked to its oil and gas production.
For astronomers, a similar path could help clarify Article IX of the 1967 Outer Space Treaty. This article stipulates that nations must take into account the interests and activities of other countries when exploring space. The ICJ will not decide the maximum number of satellites a country can launch; the expectation is to obtain an interpretation that guides states on how to weigh the impacts of their orbital operations.