The Explosive History of Orientale Basin

Orientale Basin and its multiple rings formed about 3.8 billion years ago, at the end of the conjectured Late Heavy Bombardment. None of the rings are the initial crater itself, which would fall somewhere between the sizes of the two innermost rings. The initial crater would have been obliterated by rebounding of the surface that occurred in the impact, an event that demonstrates the violence of the tremendous impacts that form basins and illustrates how basin rings might form.

A photo of the Moon's Orientale impact basin. It is colored in to show free-air gravity differentiations. There are yellow areas (average gravity), green and blue areas (below average) and red areas (above average).

This computer model of Orientale basin shows the terrain in high relief, as it would be just after sunrise. Gravity anomalies measured by the Gravity Recovery and Interior Laboratory (GRAIL) mission are depicted in different colors on the right side of the image. Red indicates areas of higher gravity, or excess mass, and blue indicates lower gravity or areas of mass deficits. The GRAIL data reveals the structure of the basin beneath the surface. The red in the center of the basin, for example, shows that the crust is particularly thin there, and that denser mantle material is closer to the surface.

NASA’s Scientific Visualization Studio

One study theorizes that the basin’s three concentric rings ― the largest three times the width of Massachusetts ― formed when around 816,000 cubic miles (3,401,236 cubic km) of ejecta, or around 135 times the combined volume of the Great Lakes, was blasted into the sky by a 40-mile-wide (64 km) impactor and came crashing back to the Moon’s surface.
The material would have risen like a tidal wave around 62 miles (100 km) above the surface ― more than 11 times the height of Mount Everest ― before collapsing, creating faults so deep they reached through the crust to the mantle. The material then sloshed back and forth for two hours, eventually settling into the two outer rings. Finally, the inner ring would have formed from the collapse of a central peak that was too massive to be stable.

Detailed view of lunar surface with many craters. In the center, a large crater has a dark, patchy floor.

The Orientale basin is the youngest of the large lunar basins. The distinct outer ring is about 590 miles (950 km) from east-to-west.

NASA/GSFC/Arizona State University

Writer: Tracy Vogel; Science Advisors: Daniel P. Moriarty (University of Maryland at College Park), Natalie M. Curran (NASA’s Goddard Space Flight Center)

Get the Basics

All About Lunar Craters

Craters are the mark the passing universe leaves on the Moon, a cosmic guestbook. They tell us the history not only of the Moon, but of our solar system.

Learn More

Aristarchus crater has slumping terraced walls and peaks in its center. The terrain looks rubble-covered and pitted.

This view of Aristarchus crater from the Lunar Reconnaissance Orbiter shows clearly terraced walls and central peaks.

NASA/GSFC/Arizona State University

Explore Further

Expand your knowledge about lunar craters.

Craters riddle the moons North Pole with the largest creating large dark grey pits. The darkest colors are at the poles, since there is less sunlight that illuminates it. The further you move out from the poles to the edge of the captured image, the lighter it becomes.

Why Study Craters

Lunar craters are about more than just the Moon.

An illustration of meteorites bombarding a landscape. The ground is bare rock, molten in places and smoking. Pools of molten rock and fires dot the terrain. Three meteorites streak through a cloudy, smoky sky.

What is the Late Heavy Bombardment?

Lunar craters give scientists a peek into our solar system’s asteroid-pummeled past.

The far side of the Moon is colored in blues, purples, greens, yellows and reds. Blue and purple, indicating lower elevations, are centered in a rough oval in the middle of the far side. This is the location of the South Pole-Aitken Basin. Craters are blue surrounded by green, yellow is scattered around the image, and red is mostly located in the upper area of the Moon. A dotted circle roughly in the center of the South Pole-Aitken Basin shows the location of the mysterious mass.

What is the South Pole-Aitken Basin?

The Moon’s largest basin holds many secrets.