Glossary of Terms

Maybe you've come across a word you don't recognize. Maybe you have heard it before, but you don"t remember what it means. You should be able to find it here. If you can"t find a definition for a term you read on this site, please feel free to email Tim Titus at


A measure of the reflectivity of light from the surface of Mars. A completely non-reflective (black) surface has an albedo of 0, while a highly-reflective (bright white) surface has an albedo of 1.
A radiant energy thermometer made of a thin wire. The electrical characteristics change as a function of radiant energy impacting it.
CO2 Ice
Condensed Carbon-Dioxide ice. Forms on Mars at about -128 C°. This is lower than Earth because of the lower barometric pressure.
Atmospheric moisture that has condensed, the resultant particles of condensation. On Mars, much of the atmosphere is CO2; as expected, much of the condensates are dry ice.
When the sun is closest to the equator. Spring equinox - Ls 0°, Autumn equinox - Ls 180°. See also Solstice.
Color used to denote a scale (or range) of values at a point.
Infrared light, long wavelength.
Solar longitude, a measure of where Mars is in its year. Mars has 4 seasons, much like Earth, in the following groups: 00° to 89° - Spring 90° to 179° - Summer 180° to 269° - Autumn 270° to 359° - Winter.
Greek for "Blanket Rock," this is simply the region of soil that covers a denser subsoil. On Mars, frozen water may be found in the top meter of regolith (soil).
When the sun is furthest from the equator. Summer solstice - Ls 90°, Winter solstice - Ls 270°. See also Equinox.
When a solid skips the liquid state and becomes a gas.
Visible light, what you and I can see.