The bright spots you can see on the Moon are areas where the surface reflects more sunlight than its surroundings. Most of them fall into three categories: fresh impact craters and their ejecta rays, the ancient mineral-rich highlands, and mysterious swirl patterns created by localized magnetic fields. Each has a different origin, but they all share one thing in common: their surface material hasn’t been darkened by the relentless bombardment of particles from space.
Why Some Lunar Surfaces Are Brighter Than Others
The Moon’s brightness variations come down to a property called albedo, which is simply how much light a surface reflects. The dark, flat plains (called maria) are made of iron-rich volcanic basalt that absorbs most sunlight. The bright regions are dominated by a mineral called plagioclase feldspar, a pale, calcium-rich crystal that reflects light efficiently. Lunar highland rocks contain 90 to 98 percent plagioclase by volume, making them dramatically lighter than the basalt-filled lowlands.
Over time, every exposed surface on the Moon gets darker. Solar wind particles and micrometeorite impacts create tiny grains of metallic iron on the outer rims of soil particles, which absorb light and gradually darken the terrain. This process, called space weathering, is why the brightest features on the Moon are also the youngest. The longer a surface sits exposed, the more it fades into the dull gray background.
Fresh Craters and Their Ray Systems
The most dramatic bright spots are young impact craters surrounded by long streaks of ejected material called rays. When an asteroid or comet slams into the Moon, it blasts through the darkened surface layer and flings fresh, unweathered rock outward in radial patterns. This freshly exposed material is rich in feldspar and hasn’t yet been darkened by solar wind exposure, so it glows bright white against the surrounding terrain.
Tycho, near the Moon’s south pole, is the most striking example. It formed roughly 108 million years ago and is surrounded by rays that stretch up to 1,500 kilometers, some reaching nearly a quarter of the way around the Moon. You can spot Tycho’s ray system with the naked eye during a full moon as pale streaks radiating from a bright point in the southern hemisphere.
Copernicus is another prominent rayed crater, sitting in the central nearside. Its central peaks contain an unusual concentration of olivine, a greenish mineral normally found deep below the surface, which was excavated during the impact. The surrounding walls and ejecta are rich in the same feldspathic material found across the highlands, keeping them visibly bright.
As centuries and millennia pass, space weathering gradually dulls these ray systems. The rays of very old craters have faded entirely, blending into the mature soil. The craters that still have visible rays are, geologically speaking, among the youngest features on the Moon.
Aristarchus: The Moon’s Brightest Crater
If you’ve ever noticed a single brilliant point on the Moon’s northwestern face, you were likely looking at Aristarchus. It’s the brightest large crater on the nearside and is visible even on the unlit portion of the Moon during earthshine. The crater sits on a raised volcanic plateau, and its walls and central peak are strongly enriched in plagioclase feldspar from the Moon’s upper crust.
The central peak of Aristarchus has three distinct brightness zones. The northern section is notably bright, the middle section matches the darker crater floor, and the southern section falls somewhere in between. The crater’s rim also contains olivine-rich material, likely excavated from a layer sitting above the ancient crust but beneath younger volcanic deposits. This mix of highly reflective crustal minerals and freshly exposed subsurface rock makes Aristarchus exceptionally luminous compared to its surroundings.
Lunar Swirls: Bright Patterns With No Crater
Some of the Moon’s bright spots aren’t craters at all. Lunar swirls are pale, sinuous markings that look almost painted onto the surface. The most famous is Reiner Gamma, a bright, tadpole-shaped feature visible through a small telescope on the western nearside. Unlike crater rays, swirls have no associated impact structure and no change in surface elevation.
Data from the Lunar Reconnaissance Orbiter’s thermal instruments confirmed that swirls form where localized magnetic fields in the lunar crust deflect the solar wind. Normally, solar wind particles slam into the unprotected Moon and gradually darken the soil through sputtering and chemical implantation. Where a magnetic anomaly exists, it acts as a miniature shield, standing off the solar wind and preventing that darkening process. The protected patches stay bright while the surrounding unshielded terrain weathers normally, creating the visible contrast.
This explanation was confirmed in part by the absence of any thermal or physical differences at swirl sites. The soil texture and rock content are the same as their surroundings. Only the degree of weathering differs, which rules out alternative theories involving comet impacts or electrically levitated dust.
The Lunar Highlands
Beyond individual craters and swirls, the broad bright regions of the Moon are the highlands, the pale, heavily cratered terrain that covers most of the farside and large portions of the nearside. These are the oldest surfaces on the Moon, dating back over four billion years to when the Moon’s original magma ocean cooled. As that ocean solidified, lighter plagioclase crystals floated to the top like foam, forming a thick feldspar-rich crust. The dark maria formed later when volcanic eruptions filled low-lying basins with dense basalt lava.
Even though the highlands are ancient and heavily weathered, they remain brighter than the maria because the underlying mineral composition reflects so much more light. Feldspar is simply a more reflective mineral than basalt, and no amount of space weathering can completely erase that fundamental difference.
When Bright Spots Are Most Visible
The best time to see the Moon’s bright spots depends on what you’re looking for. For contrast between bright and dark terrain, a full moon works well. The Moon’s brightness jumps by more than 40 percent as it approaches the exact full phase (when the Sun is directly behind you as you face the Moon). This surge is caused primarily by shadows disappearing: at full illumination, no grain of soil casts a shadow on its neighbor, so everything reflects at maximum efficiency. The effect is about 10 percent stronger in the bright highlands than in the dark maria, which means bright spots pop even more at full moon.
For detail within craters and along ray systems, a partially lit Moon is better. When the terminator (the line between day and night) crosses a feature like Aristarchus or Copernicus, the low-angle sunlight creates shadows that reveal depth and texture. Under full illumination those shadows vanish and everything flattens out, making it harder to see the structure of the bright areas even though they’re at peak reflectivity. A modest backyard telescope during the first or third quarter phase will show you ray systems, crater walls, and swirl patterns with striking clarity.