The Israeli startup Stardust, registered in Delaware, is preparing for the first tests of technology designed to artificially reduce the Sun’s brightness and cool the planet. The project, one of the most ambitious in the field of climate engineering and inspired by the effects of volcanic eruptions, was described by The New Yorker, which highlighted both its potential and its serious ethical dilemmas.

How the Technology Works: Stratospheric “Mirrors” Instead of Sulfur

Stardust’s approach is based on solar geoengineering, a method of managing incoming solar radiation. The concept is straightforward: special microparticles are dispersed into the stratosphere (above cloud level), where they reflect a portion of sunlight back into space, reducing the amount of heat reaching the Earth. This mimics the natural cooling that follows major volcanic events, such as the 1991 eruption of Mount Pinatubo, when millions of tons of sulfur dioxide led to a temporary global temperature drop of about 0.5°C.

Unlike sulfur aerosols, which can harm the ozone layer and cause acid rain, Stardust is developing “improved” particles—highly reflective but supposedly safe for ecosystems and human health. The exact composition remains confidential, but co-founder Yanai Yedwab, formerly a physicist for the Israeli government, has indicated that the particles are non-toxic and degrade naturally. The company plans small-scale trials using balloons or drones to observe how the particles behave in real atmospheric conditions.

Funding and Timeline: $60 Million for “Space Mirrors”

In October 2025, Stardust raised $60 million—an unprecedented amount for geoengineering—and brought its total funding to $75 million. Investors include Silicon Valley venture funds, an Italian industrial family, and even partners from the Israeli Ministry of Defense. The funds will be used for development and testing, and Yedwab has suggested that prototypes could be ready for deployment by the end of the decade. However, the startup stresses that the technology is meant to be a tool for governments rather than a standalone commercial launch. It is actively advocating for international regulations to prevent uncontrolled use.

The Stardust project reflects a broader global trend: geoengineering concepts have been debated for decades but are now beginning to move from theory to practice. While Harvard and several other universities have conducted small experiments, the involvement of a commercial company like Stardust is a new and controversial development.

Risks and Criticism: “Termination Shock” and Ethical Traps

Scientists warn that solar dimming is not a cure for the climate crisis. It does not reduce CO₂ levels and merely masks the symptoms, creating a risk of “termination shock”—a sudden surge in global temperatures if spraying were to stop unexpectedly. Other potential dangers include altered rainfall patterns (with droughts in some regions and floods in others), harm to the ozone layer, and negative impacts on agriculture. Critics, including experts from Columbia Business School, have questioned the safety of the project’s undisclosed particles and described the initiative as a high-speed race with no brakes.

The ethical issues are equally pressing: who has the authority to decide when the planet should be cooled? The absence of solid global regulations—only informal UN norms currently exist—allows companies like Stardust to operate in a gray area. In 2024, NOAA in the United States received a request to develop rules for such companies, but no official response has followed. Online and within scientific communities, the project has already earned the nickname “chemtrails 2.0,” a reference to conspiracy theories.

Despite widespread skepticism, supporters view the technology as a potential “Plan B” for a scenario in which emissions are not reduced in time. Yedwab has emphasized that Stardust is intended as a research initiative rather than a tool for mass cooling.

In Brief

The startup Stardust (Israel/US) plans to test microparticles designed to reflect sunlight and mimic volcanic cooling effects as a means of lowering global temperatures. With $60 million in new investment and a stated focus on safety, the project highlights the urgency of establishing international frameworks for solar geoengineering. Although risks—from termination shock to ethical governance—remain substantial, the initiative signals a shift toward real-world experimentation. Ultimately, genuine climate solutions still lie in decarbonization rather than dimming the Sun.