The sky comes from lookup tables precomputed with mars_sky.py. That model handles Mie scattering by dust in 41 wavelength bands, CO₂ Rayleigh scattering, single scattering ray-marched through a spherical atmosphere, and Monte Carlo multiple scattering with a Lambertian soil. The viewer reduces this to 8 bands and interpolates over Sun elevation and dust optical depth. The dust phase function is applied exactly at every pixel.
Papers supplied for this work
- Bell, J. F. III, Savransky, D. & Wolff, M. J. (2006). Chromaticity of the Martian sky as observed by the Mars Exploration Rover Pancam instruments. J. Geophys. Res. 111, E12S05. doi:10.1029/2006JE002687. Calibrates sky colour against measured chromaticity vs τ; also checks soil colour.
- Thomas, N., Markiewicz, W. J., Sablotny, R. M., Wuttke, M. W., Keller, H. U., Johnson, J. R., Reid, R. J. & Smith, P. H. (1999). The color of the Martian sky and its influence on the illumination of the Martian surface. J. Geophys. Res. 104(E4), 8795–8808. Checks the reddened diffuse vs direct illumination.
- Thomas, N., Markiewicz, W. J., Sablotny, R. M. & Keller, H. U. The Martian sky and its illumination of the Martian surface (conference abstract). Background on sky brightness and diffuse flux.
- Ehlers, K., Chakrabarty, R. & Moosmüller, H. (2014). Blue moons and Martian sunsets. Applied Optics 53(9), 1808–1819. doi:10.1364/AO.53.001808. Dust size distribution and Mie approach; explains the blue glow around the Sun.
- Collienne, P., Wolff, R., Gerndt, A. & Kuhlen, T. (2013). Physically based rendering of the Martian atmosphere. GI VR/AR Workshop. Precomputed-scattering approach for real-time rendering.
- Meyran, T. (2022). Physically Based Real-Time Rendering of the Martian Atmosphere. MSc thesis, Hochschule Hannover. Model comparison, MER data, and the need for a non-spherical side-scatter correction.
Other methods and constants
- Tomasko et al. (1999), JGR 104, 8987: dust effective radius 1.6 µm, variance 0.2. Hansen & Travis (1974): gamma size distribution.
- Wolff et al. (2009), JGR 114, E00D04: spectral shape of dust absorption; level calibrated to Bell et al. (2006).
- Bohren & Huffman (1983): Mie theory. Sneep & Ubachs (2005): CO₂ King factor. Costa et al. (2021): CO₂ refractivity.
- Archinal et al. (2018), IAU WGCCRE 2015: Mars orientation and ellipsoid. Allison & McEwen (2000), Mars24: Ls, local mean solar time, Mars year.
- Espenak & Meeus: ΔT outside the leap-second era. Ballesteros (2012): star colour from B−V.
Source data
- JPL DE430 planetary ephemeris (NAIF): Sun, planets, Earth and Moon, fitted with Chebyshev series for 1950–2100 (error < 0.0001°).
- JPL MAR099 Mars satellite ephemeris (NAIF): Phobos and Deimos, fitted with precessing ellipses for 1995–2050 (error < 7 km).
- Yale Bright Star Catalogue, 5th rev. ed. (Hoffleit & Warren 1991): 8,404 stars brighter than V = 6.5.
- Solar spectrum: ASTM E-490-based extraterrestrial spectrum (ASTM G173-03). Colour: CIE 1931 2° observer.