commettras

Commetras are a theoretical class of microscopic particles proposed to exist in the dust tails of comets. Used in speculative astronomy and fiction, commetras are imagined as compact, elongated grains that interact with sunlight in distinctive ways.

The term is a compound of “comet” and a Greek-root element meaning measure or metric, reflecting their imagined role as quantifiable constituents of a comet’s dust environment.

Typical descriptions place commetras at sizes of roughly 50–500 nanometers in length with cross-sections of 5–20 nanometers. They are imagined to consist of silicates and organic components, possibly coated with volatile ices. Their orientation with respect to the Sun could produce unique polarization signals, and their infrared spectral features would reflect a composite mineralogy.

Evidence for real commetras is, at present, hypothetical. Some models suggest they could help explain unusual polarization-phase curves or color gradients observed in certain comets. Detecting commetras would likely require high-contrast polarimetry and sensitive infrared spectroscopy, and researchers often point to laboratory analogs to study their proposed properties.

In fiction and thought experiments, commetras are used to illustrate dust processing, radiative interactions in dusty environments, and the microphysics of cometary materials, offering a framework for exploring how tiny particles influence the appearance and evolution of comets.