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The Moon has Two Grand Canyons, Carved in Minutes by an Asteroid Impact

By Carolyn Collins Petersen | Published on February 7, 2025

Our Moon continues to surprise us with amazing features. Scientists recently shared new information about two canyons that branch out from a major lunar impact. The site is the Schrödinger basin near the Moon's South Pole. It formed when an asteroid or possibly even a leftover planetesimal slammed into the surface. It took only minutes to dig out that huge crater and split the landscape to make two huge rifts that extend from the site.

According to David Kring of the Lunar and Planetary Institute in Houston, TX, the impact is of very ancient origin. “Nearly four billion years ago,” he said, “an asteroid or comet flew over the lunar south pole, brushed by the mountain summits of Malapert and Mouton, and hit the lunar surface. The impact ejected high-energy streams of rock that carved two canyons that rival the size of Earth’s Grand Canyon. While the Grand Canyon took millions of years to form, the two grand canyons on the Moon were carved in less than 10 minutes.”

“The two canyons on the Moon were carved in less than 10 minutes.” – David Kring

Dimensions of the Canyons

Those two canyons—named Vallis Schrödinger and Vallis Planck—are significant clues to that turbulent time in the Moon’s past. And, they’re impressive. Vallis Schrödinger is just under 300 kilometers long, 20 km wide, and 2.7 kilometers deep. Vallis Planck has two units. One is a deep canyon within the ejecta blanket of debris thrown out by the impact. The rest comprises a row of craters made as falling rocks were thrown out from the impact. They fell back to the Moon to create so-called “secondary craters.” The canyon part is about 280 kilometers deep, 27 km wide, and 3.5 km deep. The depth of both of these canyons surpasses the deep gorges of Earth’s Grand Canyon in Arizona.

Geological Significance

The impactor probably slammed into the surface at nearly 55,000 kilometers per hour, producing the enormous 320-kilometer-diameter Schrödinger impact basin. In the aftermath, the rocky debris scoured the deep canyons.

Anatomy of an Impact and Its Aftermath

The Schrödinger basin formed in the outer margin of the South Pole-Aitken (SPA) basin. At a diameter of about 2,400 km, it’s the largest and oldest impact basin on the Moon. The basin’s rim is about 300 km from the South Pole and within 125 km of the proposed exploration site for the Artemis mission, which will mark a significant return of human activity to the Moon.

Geological Features of Schrödinger

The Schrödinger crater has a ~150-km diameter peak ring and the whole area is surrounded by a blanket of impact ejecta that splashed out in an irregular pattern up to 500 km away. The outermost crater ring resembles a circular mountain range and rises 1 to 2.5 km above the basin floor. After the impact, basaltic lava flows flooded the area. A large pyroclastic vent erupted more material onto the basin floor. That volcanic activity ended around 3.7 billion years ago.

Impact Anomalies

A careful analysis of the impact basin, the canyons, and the ejecta surrounding the site by Kring and a team of scientists at the Lunar Planetary Laboratory gives an idea of impact details. The canyons have rays that don’t converge at the basin’s center as you might expect from typical impacts; they seem to converge at a different point. This implies a point explosion impact.

Future Exploration

These rays and the impact basin are set to be exploration points for NASA’s upcoming Artemis missions. The evidence from the ejecta blanket indicates an uneven distribution, particularly in the area where the first missions are planned. This will allow astronauts and robotic probes to reach underlying samples of the Moon’s primordial crust without having to dig through younger rocks.

Since the basin is the second-youngest basin on the Moon, the impact melted rocks will be a great way to test the actual age of the impact. It is generally understood that around 3.8 billion years ago, the Moon (and Earth) experienced a multitude of such collisions during a period known as the Late Heavy Bombardment, lasting up to 200 million years. The continual impacts during this epoch significantly scarred the surfaces of not only the Moon but also other rocky planets and asteroids.

Additional Resources

For more information, refer to the following resources:

• Grand Canyons on the Moon (journal article)
• Grand Canyons on the Moon

Explore more about lunar geology and the significance of recent findings at Universe Today.

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