The nonprofit announced today that after unfurling its solar sail last week, the tiny spacecraft has successfully leveraged photons from the Sun to shift its trajectory in Earth orbit, a landmark moment in the history of space exploration.

The idea that sunlight exerts pressure on objects and could therefore, theoretically at least, offer a form of propulsion dates back to the 17th century, when German astronomer Johannes Kepler spotted comet tails blowing about by what he believed to be a solar breeze. More recently, Carl Sagan began throwing the idea of solar sailing around in the 70s, and in co-founding The Planetary Society in 1980, hoped to explore the concept as part of a wider mission to further our understanding of space.

All of which is to say that this moment has been a long time coming for The Planetary Society, and the scientific community as a whole. Other spacecraft have used forms of solar propulsion before, such as NASA's Mariner 10, which ran out of fuel on the way to Mercury and used solar arrays to control its orientation.