On December 12, 2025, a team of astronomers at the Armagh Observatory and Planetarium (AOP) witnessed something truly rare—a brief flash of light on the Moon’s surface caused by a meteoroid impact. This groundbreaking discovery, the first of its kind captured in Ireland, offers a rare glimpse into the Moon’s dynamic and often violent nature. As part of their ongoing research into the impacts that shape our lunar neighbor, AOP’s work is pushing the boundaries of what we know about the Moon and the constant bombardment it endures from space debris.
The Rarity of Lunar Impact Flashes
Lunar impact flashes are phenomena that occur when small meteoroids, traveling at incredible speeds, strike the Moon’s surface. These impacts are often too brief and faint to be detected by the naked eye, making them a rare and exciting discovery for astronomers. The flash itself is a brief burst of light, caused by the high-energy collision that vaporizes material at the impact site. The Armagh Observatory’s recent observation, captured at precisely 03:09:36 UTC on December 12, 2025, has provided fresh insights into these events, which are usually short-lived, lasting just fractions of a second.
Astronomers have been studying lunar impact flashes for years, but they remain difficult to observe. The objects responsible for these flashes are typically very small—often no bigger than a golf ball—and are almost impossible to detect while they are in space. When they strike the Moon, they travel at extraordinary speeds—around 35 km/s in this particular case—making their impact extremely energetic. The kinetic energy from this high-speed collision is rapidly converted into heat and light, creating the flash seen from Earth. This unique phenomenon, which had been seen very occasionally, has now been documented by the Armagh Observatory team, shedding new light on the Moon’s vulnerability to such impacts.
The Importance of the Armagh Observatory’s Robotic Telescope
The Armagh Observatory and Planetarium’s success in capturing this rare event was made possible by its advanced technological infrastructure, particularly the Armagh Robotic Telescope (ART). The ART played a crucial role in detecting the impact flash, providing precise, high-speed video footage of the Moon’s night side. The telescope’s sensitivity to even the faintest of events, coupled with the use of fast cameras, allowed astronomers to capture the fleeting moment of impact.
Andrew Marshall-Lee, a final-year PhD student at AOP, was instrumental in this groundbreaking observation. His careful monitoring and use of ART contributed significantly to the success of this mission. Observing such events requires a combination of specialized equipment and patience, as lunar impact flashes are not only rare but also hard to spot. The data collected during this event will contribute to our understanding of meteoroid impacts on celestial bodies, and could potentially assist in future lunar exploration and space missions.
Geminid Meteor Shower: The Likely Cause of the Lunar Impact
The timing of the lunar impact flash coincided with the peak of the Geminid meteor shower, which is known for producing meteoroids that could have caused the observed flash. The Geminid meteor shower, one of the most prolific meteor showers of the year, originates from debris left behind by an asteroid, and is famous for producing bright meteors that streak across the sky. Given the timing, it is likely that the meteoroid responsible for the flash was a fragment from this shower. However, the exact origin of the meteoroid is still under investigation.
Lunar impact flashes are more likely to occur during meteor showers like the Geminids, as the Moon passes through streams of debris from comets and asteroids. These debris streams contain meteoroids, many of which are small enough to produce flashes when they strike the Moon. The Geminid meteor shower is particularly active in December, making it an ideal time for observing lunar impacts, and offering a unique opportunity for astronomers to study the effects of meteoroid collisions on the Moon.
Challenges of Detecting Lunar Impact Flashes
Detecting lunar impact flashes is no simple feat. The Moon’s surface, often obscured by sunlight, is difficult to monitor in detail without precise instruments. The flashes themselves last only fractions of a second, making them hard to catch with standard telescopes. For astronomers to observe these flashes, specialized equipment, including telescopes with at least a 20 cm aperture, and fast cameras are essential. Furthermore, monitoring the Moon’s dark side, where impact flashes are most likely to occur, requires a great deal of patience and careful observation.
The rare nature of these flashes means that even experienced observers may miss them. As seen in this case, the capture of a lunar impact flash requires both luck and skill. The Armagh Observatory’s team, using the ART, has demonstrated the potential of robotic telescopes in capturing such fleeting events. This breakthrough will undoubtedly encourage further advancements in lunar research and observation, helping to uncover more secrets about the Moon’s dynamic surface.
