space exploration•Mon, September 21, 2026•4 min read

NASA Discovers Rare, Massive Lunar Crater Larger Than the Roman Colosseum

NASA scientists have identified a massive, pristine crater on the Moon formed by a rare, once-in-a-century impact event. The discovery, captured by the Lunar Reconnaissance Orbiter, offers a unique opportunity to study how lunar craters form and evolve in real-time.

A Rare Glimpse Into Lunar History

In a remarkable astronomical event, NASA has discovered a massive new crater on the Moon that stands out for both its size and its pristine condition. Measuring 225 meters (738 feet) in diameter, the crater is larger than the Roman Colosseum. Identified by researchers using data from the Lunar Reconnaissance Orbiter (LROC), the site—officially named McGetchin—is providing scientists with a rare, real-time look at how planetary surfaces are shaped by high-energy impacts.

The newly identified McGetchin crater, a rare pristine impact site on the lunar surface.

Why This Discovery Is a 'Once-in-a-Century' Event

The Moon is famously pockmarked with craters, but most are ancient, formed billions of years ago and subsequently eroded by eons of space weathering. McGetchin is different. Because it is a large, fresh impact, it serves as an invaluable reference point for planetary scientists.

Impact magnitude: Scientists estimate the crater was formed by a comet or asteroid roughly the size of a three- to six-story building.
Rarity: Such large, pristine impact events are estimated to occur on the Moon only about once every 100 to 136 years.
Data analysis: Researchers utilized 'before-and-after' images captured by the LRO to confirm the crater’s recent formation.
Scientific value: The discovery allows researchers to test and refine existing models of small-impact crater formation.

The fact that we have meter-scale before-and-after images of a 225-meter [738-foot] diameter crater provides a unique opportunity to test models of small-impact crater formation.
— Mark Robinson, Principal Investigator for the LROC

The Role of the Lunar Reconnaissance Orbiter

The discovery was announced at the 57th Lunar and Planetary Sciences Meeting. The LROC team found the crater during routine analysis, which involved comparing lunar images over time to detect surface changes. This mission, now 16 years into its tenure in space, continues to be a cornerstone of our understanding of the Moon’s dynamic environment. By identifying McGetchin, NASA has secured a 'control group' for studying impact mechanics, helping experts better understand not just the Moon, but the history of our entire solar system.

Key Takeaways

NASA identified a 225-meter (738-foot) wide crater on the Moon, named McGetchin.
The crater is larger than the Roman Colosseum and was formed by an asteroid or comet up to six stories tall.
Impacts of this magnitude are extremely rare, estimated to occur roughly once every century.
The site provides a 'pristine' reference point for scientists to study modern lunar crater formation.
The discovery was made by the Lunar Reconnaissance Orbiter (LRO) team via comparative image analysis.

FAQ

How large is the newly discovered moon crater?

The crater, named McGetchin, measures approximately 225 meters (738 feet) in diameter.

How often do craters of this size form on the Moon?

Scientists estimate that an impact of this magnitude happens on the Moon only once every 100 to 136 years.

What caused the crater?

Researchers believe the crater was created by a comet or asteroid roughly the size of a three- to six-story building.

Why is this specific crater important for scientists?

Because the crater is pristine and well-documented with 'before-and-after' imagery, it provides a rare, modern baseline to test models of how impact craters form.