Sun Block

As humanity emits more and more greenhouse gases, the Earth’s atmosphere traps more and more of the sun’s energy—steadily increasing the Earth’s temperature. One strategy for reversing this trend is to intercept a fraction of sunlight before it reaches our planet. For decades, scientists have considered using screens, objects, or dust particles to block just enough of the sun’s radiation—between 1 and 2 percent—to mitigate the effects of global warming.

A U-led study explored the potential of using dust to shield sunlight and found moondust may be the best way to shade the planet. The scientists analyzed different properties of dust particles, quantities of dust, and the orbits that would be best suited for shading Earth. The authors found that launching dust from Earth to a way station at the Lagrange Point between Earth and the sun would be most effective but would require astronomical cost and effort. An alternative is to use moondust. The authors argue that launching lunar dust from the moon instead could be a cheaper and more effective way to shade the Earth.

“That was the seed of the idea; if we took a small amount of material and put it on a special orbit between the Earth and the sun and broke it up, we could block out a lot of sunlight with a little amount of mass,” says Ben Bromley, professor of physics and astronomy and lead author of the study.

“It is amazing to contemplate how moon dust—which took over four billion years to generate—might help slow the rise in Earth’s temperature, a problem that took us less than 300 years to produce,” says study co-author Scott Kenyon, from the Center for Astrophysics | Harvard & Smithsonian.

The study authors stress that they only explored the potential impact of this strategy, rather than evaluating whether these scenarios are logistically feasible.

“Our strategy could be an option in addressing climate change,” says Bromley, “if what we need is more time.”