24 Themis

Within modern astronomical nomenclature, 24 Themis was discovered by Annibale de Gasparis and named (per convention) after the Greek personification Themis; the name links classical mythic nomenclature with scientific taxonomy. Dynamically, Themis is interpreted as the parent body of a collisional family in the outer main asteroid belt rather than a mythic agent.

Approximately 200 kilometres (roughly 120–123 miles) in diameter, 24 Themis is observed via telescopic spectra rather than resolved surface imagery. Spectral data indicate a dark, brown to reddish surface consistent with tholins and carbonaceous material, and infrared observations are interpreted as showing surfaces coated with water ice and organic compounds (including tholins, asphaltite-like materials, carbonaceous meteorite material, and polycyclic aromatic hydrocarbons).

As a natural object, Themis follows an elliptical orbit about the Sun (semi-major axis ≈ 3.1302 AU, period ≈ 5.54 years, low inclination ≈ 0.76°, eccentricity ≈ 0.1306). Surface processes inferred from observations include the presence and possible sublimation of water ice, surface replenishment via impact gardening or exposure of subsurface ice, and chemistry driven by space-weathering (irradiation producing tholin-like residues). Themis' mass and gravitational perturbations have been used in dynamical studies (for example, to estimate masses via perturbations of nearby asteroid orbits).