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THE 42 INDEX

Psyche radar albedo

0.42

Measured

Shepard et al. 2008 mean OC radar albedo of (16) Psyche, 0.42

The metal world of asteroid 16 Psyche, from the Psyche site.

ArtPsycheScribe art

A 2008 radar paper printed Psyche’s mean radar albedo as 0.42, ranging from 0.26 to 0.51. The number is a published measurement. It is not Psyche’s eternal 42.

What it supports

Shepard, Clark, Nolan et al., Icarus 195 (2008): when radar albedo is normalized by a bandwidth-based area proxy, the mean is 0.42. High reflectivity helped the metal-near-surface reading. Later work moved the mean: Shepard 2017 prints 0.37 ± 0.09; a 2021 shape paper prints 0.34 ± 0.08.

What it does not

Not “Psyche’s albedo is 42.” Not an invariant of the rock. Optical albedo is a different number.42.

ExactnessApproximate

Form4.2

Unitradar albedo

Strengthhard

When2008

Source

Shepard et al. 2008 · Icarus 195:184

Owner

Psyche