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A huge space rock roughly the size of a six-storey building slammed into the
Moon, creating an enormous new crater in an event scientists describe as an
exceptionally rare, “once-in-a-lifetime” observation.
The powerful lunar impact created a crater approximately 728 feet (222 meters)
wide and up to 141 feet (43 meters) deep. According to researchers, it is the largest
newly formed impact crater identified on the Moon and the largest newly formed
crater ever discovered in the solar system.
Scientists believe an impact capable of producing a crater of this scale may
happen on the Moon only about once every century or longer. The discovery
therefore gives researchers an unusual opportunity to examine what happens
immediately after a major asteroid or comet fragment collides with the lunar
surface.
The discovery is particularly important as NASA and other space agencies prepare
for a new era of lunar exploration, including plans for astronauts to return to the
Moon and establish a more sustained human presence.
NASA Discovers a Remarkable New Lunar Crater
The story began during what was initially a routine examination of data collected
by NASA's Lunar Reconnaissance Orbiter (LRO).
Robert Wagner, an image-processing specialist working with the Lunar
Reconnaissance Orbiter Camera system, was examining large maps of the Moon
when he noticed an unusual bright feature surrounded by a darker halo.
The strange pattern suggested that something had dramatically disturbed the lunar
surface.
Rather than ignoring the unusual image, Wagner investigated further. By comparing
older photographs of the same region with newer observations, scientists were
eventually able to confirm that the feature was a newly created impact crater.
The crater was later officially named McGetchin crater, in honor of lunar scientist
Thomas McGetchin, a former director of the Lunar and Planetary Institute in
Houston.
Researchers determined that the crater formed on the eastern side of the Moon
sometime between April 11 and May 22, 2024, after a comet or asteroid fragment
struck the surface.
The object responsible for the collision was estimated to have been between the
size of a three-storey and six-storey building.
A Massive Impact on the Moon
The scale of the impact surprised researchers.
McGetchin crater stretches roughly 728 feet across, a distance comparable to two
football fields placed end to end. Its depth reaches approximately 141 feet,
illustrating the tremendous amount of energy released when the space rock hit the
Moon.
Unlike Earth, the Moon has virtually no atmosphere capable of slowing down
incoming meteoroids and asteroids. As a result, space rocks can reach the lunar
surface at extremely high speeds.
When a large object hits the Moon at such velocity, an enormous amount of energy
is released almost instantly. Rock, dust and lunar soil are blasted away from the
impact site, creating a crater and spreading debris across the surrounding
landscape.
Scientists estimate that an impact powerful enough to create a crater of
McGetchin's size occurs on the Moon only around once per century.
That rarity is one reason researchers consider the observation so valuable.
Why Scientists Call It a “Once-in-a-Lifetime” Discovery
The significance of McGetchin crater goes beyond its impressive size.
Most lunar craters are extremely old. Over millions or billions of years, repeated
impacts and the effects of space weathering gradually alter their shape and
appearance.
McGetchin is different.
Because researchers have images of the area from before the impact and
observations from after the event, they can study how a fresh lunar crater develops
and how an asteroid impact changes its surroundings.
Scientists described the event as a statistically rare observation that effectively
occurs only once in a lifetime.
The opportunity to observe a major impact site so soon after its formation
provides valuable information about lunar geology, asteroid impacts, regolith
behavior and the evolution of planetary surfaces.
It also demonstrates the importance of maintaining long-term space missions
capable of repeatedly observing the same regions.
The Impact Changed the Lunar Surface Far Beyond the Crater
The crater itself is enormous, but the effects of the collision extend considerably
farther.
Images from the Lunar Reconnaissance Orbiter Camera revealed an extensive layer
of material thrown outward from the crater. This material, known as ejecta, spread
across the Moon's surface after the collision.
Researchers found that the impact disturbed the lunar landscape across an area
extending more than 100 kilometers.
The material was also ejected at a higher angle than scientists initially expected.
This finding could help researchers improve models used to understand how
asteroid and comet impacts distribute rocks and dust across planetary surfaces.
Understanding ejecta patterns is particularly important for future lunar missions
because astronauts, spacecraft and robotic vehicles may eventually operate close
to areas affected by previous impacts.
A Strange Cold Spot Appeared Around the Crater
One of the most interesting discoveries came from another instrument aboard
NASA's Lunar Reconnaissance Orbiter.
Scientists studying data from the spacecraft's Diviner Lunar Radiometer detected a
large temperature anomaly surrounding McGetchin crater.
The affected region is approximately 4 to 4.3 miles (6.4 to 7 kilometers) wide.
During the lunar night, this area was found to be roughly 14 to 16 degrees
Fahrenheit (8 to 9 degrees Kelvin) colder than the surrounding surface.
Researchers believe the temperature difference is linked to changes in the Moon's
upper layer of soil, known as regolith.
The impact disturbed and loosened the regolith, effectively making the material
more porous and less compact. This “fluffier” layer does not retain heat as
effectively, resulting in a cooler surface during the long lunar night.
The discovery is significant because it demonstrates that a major asteroid impact
can alter the Moon's thermal properties over an area much larger than the crater
itself.
What Is Lunar Regolith?
Lunar regolith is the loose layer of dust, broken rock and soil covering much of the
Moon.
It has been shaped by billions of years of asteroid and meteoroid impacts.
Every time a space rock strikes the Moon, material can be excavated and thrown
outward. Over extremely long periods, this continuous process gradually mixes and
overturns the upper layers of lunar soil.
NASA's long-running observations suggest that the Moon's upper inch of soil may
be overturned by ejecta approximately every 80,000 years.
That means the lunar surface is much more dynamic than its seemingly quiet
appearance might suggest.
The Moon does not have the wind, rain and flowing water that constantly reshape
Earth's landscape, but impacts from space continue to modify its surface.
NASA's Lunar Reconnaissance Orbiter Plays a Major Role
NASA's Lunar Reconnaissance Orbiter has been studying the Moon for more than 17
years.
The spacecraft carries seven scientific instruments designed to investigate different
aspects of the lunar environment, including its surface, topography, composition,
temperature and radiation conditions.
During its mission, LRO researchers have identified at least 1,000 new impact
craters and documented tens of thousands of additional surface changes caused
by impacts and the debris they produce.
The spacecraft's cameras allow scientists to examine the Moon at different levels of
detail.
The Wide-Angle Camera can capture broad areas of the lunar surface, while the
Narrow-Angle Cameras provide much higher-resolution images.
Together, these systems allow researchers to detect both large geological changes
and relatively small new craters.
How Was McGetchin Crater Found?
Finding a new crater may sound straightforward, but it is a highly demanding
scientific process.
Researchers regularly compare modern lunar images with older maps and
photographs.
Computer software can highlight areas that have changed. However, changes in
lighting, shadows and viewing conditions can create large numbers of false signals.
Scientists therefore need to manually examine potential discoveries.
In Wagner's case, the new crater stood out because of its unusually large debris
pattern.
After the initial discovery, researchers used higher-resolution images from the
Lunar Reconnaissance Orbiter Camera to examine the crater in much greater
detail.
These observations helped scientists determine the crater's dimensions, shape and
surrounding ejecta.
The data also helped researchers estimate the size and energy of the object
responsible for the impact.
The Moon Is Constantly Being Hit by Space Rocks
Although McGetchin crater is exceptional, the Moon is regularly struck by smaller
objects.
The absence of a substantial atmosphere means that many meteoroids can reach
the lunar surface without burning up or slowing significantly.
Scientists can identify some of the smallest impact craters visible in LRO imagery
at approximately 30 feet across.
These smaller craters can be produced by rocks measuring roughly 43 inches
across.
Researchers estimate that impacts capable of producing craters of this smaller
scale create around 140 new craters across the Moon every year.
However, most incoming particles are far smaller and produce impacts that cannot
easily be distinguished in orbital images.
This constant bombardment makes the Moon an important natural laboratory for
studying impact processes throughout the solar system.
What Does the Discovery Mean for Future Moon Missions?
The discovery of McGetchin crater could have practical implications for future lunar
exploration.
NASA and other space agencies are developing increasingly ambitious plans for
robotic and crewed missions to the Moon.
As astronauts and robotic vehicles spend more time on the lunar surface,
understanding how asteroid impacts modify the terrain could become increasingly
important.
For example, impact debris can change the texture and stability of lunar soil.
That could affect how lunar rovers, landers and other spacecraft move across the
surface.
The discovery also raises questions about the potential risks posed by ejecta from
future impacts near human settlements or scientific facilities.
Researchers say an important next step is to better understand the likelihood of
material thrown from new craters reaching areas where future lunar bases could be
located.
A Natural Laboratory for Space Science
McGetchin crater offers researchers something rarely available in planetary
science: a relatively fresh impact site with detailed observations from before and
after the collision.
Its location is also scientifically interesting because it lies near a boundary between
darker basalt-covered lunar plains and brighter highland terrain.
Studying how the impact affected these different geological environments could
provide additional information about the Moon's surface composition and history.
A future robotic or crewed mission could potentially investigate the crater directly.
Surface observations would allow scientists to connect orbital images with details
that are difficult to determine from spacecraft alone, including the texture of the
soil, the distribution of impact debris and small-scale changes in the lunar
landscape.
What Scientists Can Learn From the Moon's New Crater
Large asteroid impacts are among the most important geological processes in the
solar system.
Studying them helps researchers understand not only the Moon, but also other
rocky worlds, including Earth, Mars and asteroids.
Fresh craters provide an opportunity to examine the physical effects of high-speed
collisions before subsequent impacts and space weathering significantly modify
the evidence.
The McGetchin discovery therefore represents more than another addition to the
Moon's enormous collection of craters.
It provides a detailed case study of how an asteroid or comet fragment can reshape
a planetary surface.
The observations may also improve scientific models used to assess asteroid
impact risks, lunar surface evolution and future space exploration.
A Rare Moment in the History of Lunar Exploration
The Moon may appear unchanged when viewed from Earth, but its surface
continues to evolve.
Every incoming meteoroid, asteroid fragment and comet fragment can leave a
mark.
Most of those impacts are too small to be detected from orbit. Occasionally,
however, a much larger object creates a feature that scientists can observe and
study in extraordinary detail.
McGetchin crater is one of those rare events.
The crater's enormous size, extensive debris field and surrounding thermal anomaly
give scientists an unusual opportunity to study the immediate consequences of a
major lunar impact.
As NASA and other space agencies prepare for the next generation of Moon
missions, lunar bases, robotic exploration and human spaceflight, discoveries like
this could become increasingly important.
The Moon is not simply a destination for future astronauts. It is also a natural
laboratory where scientists can investigate planetary geology, asteroid impacts
and the processes that have shaped the solar system for billions of years.
For researchers, the discovery of McGetchin crater is therefore a remarkable
reminder that even after decades of lunar exploration, the Moon can still produce
extraordinary scientific surprises.
