Astronomers are gearing up for a unique moon observation event: a stray piece of a SpaceX Falcon 9 rocket is on track to hit the lunar surface on August 5. The collision and its aftermath, which may be visible from Earth and space-based telescopes, present an opportunity for some singular science.
In a new paper posted to the preprint server arXiv.org, 23 astronomers call on the scientific community to observe the event and note that it may be possible to record the impact as it happens. The crash could reveal new information about what happens in the immediate aftermath of an impact on the lunar surface and offer insights into the hazards of errant space junk to the moon.
The meandering spacecraft was first spotted by amateur astronomer Bill Gray. Launched in January 2025, the Falcon 9 ferried two landers to the moon—Firefly Aerospace’s Blue Ghost and Japanese firm ispace’s Hakuto-R. After delivery, the rocket’s upper stage was meant to burn up on reentry in Earth’s atmosphere. But as Scientific American reported in May, that didn’t happen.
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Instead it entered orbit around Earth at a similar distance as the moon. Objects such as this are challenging to track from our planet, Gray noted in a recent blog post. The rocket fragment’s motion is hard to predict, Gray wrote, because it is under the influence of both gravity and solar radiation pressure, a subtle force that effects its direction of travel in ways that are difficult to forecast.
Gray predicted that the 10,800-pound space junk will hit the moon at approximately 2:34 A.M. EDT on August 5 and that it will crash close to the edge of the moon, as seen from Earth, near Einstein Crater. When it smashes into the moon, it will be traveling at 5,400 miles an hour—several times the speed of sound—and with similar energy to three tons of TNT, according to Gray.
In the new preprint, astronomers (including Gray) write that detecting the impact flash will likely be challenging because of the probable crash location on the sunlit hemisphere of the moon. Indeed, no artificial or natural impact flashes have ever been seen on the lit surface of the moon, they write.
“The fact that the impact is really close to the limb may actually turn out to be an advantage. Rocks ejected by the impact may form a ‘plume’ that will be visible against the dark background once they’re off the moon,” Gray wrote in his blog post, adding that what will be visible will become more apparent as the impact approaches.
“Maybe we’ll see the flash,” he wrote. “Maybe we’ll see rocks ejected from the crater. Maybe we’ll even see both.”
The crater will probably be most visible using space-based observatories, and NASA’s Lunar Reconnaissance Orbiter is set to image the impact site both before the collision and after, according to the paper. South Korea’s Pathfinder Lunar Orbiter will also attempt to observe the rocket fragment as it impacts the lunar surface and to survey the aftermath.
In the paper, the authors encourage anyone able to observe the impact to give it a try—and point to guides to help amateurs.
“The upcoming Falcon 9 upper stage impact on the Moon on 2026 August 5, presents an ideal opportunity for observers in the Americas and space-based assets to study a significant lunar impact in real time,” they write.
The event is timely, the paper argues: NASA and other space agencies are ramping up their lunar ambitions, with plans for human missions to the moon and, eventually, permanently staffed moon bases. Tracking space debris in lunar orbit will be crucial for these efforts, the authors note.