Slithera: Atmospheric Dispersion
Cosmology & the Sky arc, page 163 of 193. Back to The Pixelated Physics Universe
Who they are
Slithera has one line, and says it often: “Slit along parallactic or lose the blue.”
Slithera is a character of the Cosmology & the Sky arc: drawn in pixels, ruled by one piece of real physics, and never allowed to break it.
The physics
Atmospheric differential refraction disperses star images vertically; align the slit along the parallactic angle to avoid losing blue light.
$$ \begin{gathered} R \approx (n - 1)\tan z \\ \Delta R = (n_{\lambda_1} - n_{\lambda_2})\tan z \end{gathered} $$
| Symbol | Meaning | SI unit |
|---|---|---|
| $R$ | atmospheric refraction | — |
| $n$ | refractive index of air | — |
| $z$ | zenith angle | — |
| $\Delta R$ | differential refraction between two wavelengths | — |
Sources
Crossovers
Slithera meets Thermal Mirage (Heat Refraction / Optical Distortion). Thermal Mirage's air bends light by temperature. Slithera's air bends it by wavelength, spreading a star's image into a short spectrum near the horizon.
Slithera meets Secantha (Airmass Sec Z). Secantha's target is setting into thicker air. Slithera warns that atmospheric dispersion grows with the zenith angle too, so the slit should be aligned to the parallactic angle.
Wear the lore
Concept keywords: Atmospheric Dispersion, Slithera, Cosmology & the Sky, physics lore, Pixelated Physics