Why do asteroid albedos vary so widely?

Asteroid albedos vary widely—ranging from approximately 0.02 to over 0.5—primarily because they reflect the diverse chemical and mineralogical compositions of the asteroids' surfaces.1

Scientists classify asteroids into various taxonomic groups based on their albedo and spectral reflectance measurements. These variations in reflectivity are linked to the specific materials present on an asteroid's surface:2

• Low-albedo asteroids (e.g., C, D, P, F classes): These objects typically have albedos between 0.02 and 0.07. Their surfaces often contain carbon-rich materials, organic-rich silicates, or iron-bearing hydrous silicates, which absorb more light.23
• Moderate-albedo asteroids (e.g., S, M, K classes): These range from 0.08 to 0.28 and often contain significant amounts of metals (such as nickel-iron) or silicates like olivine and pyroxene.23
• High-albedo asteroids (e.g., E, A, R, V classes): With albedos greater than 0.28, these surfaces often match the composition of specific achondrite meteorites, such as enstatite or basaltic materials.2

Additionally, surface properties can be modified over time by space weathering, where impacts and solar radiation alter the chemical and physical characteristics of the surface, further influencing how much light an asteroid reflects.3