The reflective power of a given surface is called the albedo ("whiteness" in Latin), which is the ratio of reflected energy compared to the amount hitting the surface. An opaque object that reflects 80% of the electromagnetic energy has an 80% albedo and absorbs 20%.
Albedo is an important concept related to climate change. Snow and ice have a high albedo and reflect most of the sun's energy back into space. Water, soil, and plants have a lower albedo, and absorb more solar energy, which contributes to warming and heating in the atmosphere. This, in turn, leads to more melting of snow and ice, which leads to more warming, especially in polar regions. This cycle is an example of a positive feedback loop.
The term liquid crystal sounds like an oxymoron. However, if you examine molecules of a liquid crystal that are close to one another, they will be arranged in an orderly structure, like a crystal. If you examine molecules that are separated by longer distances, the molecules will be disordered, as they would be in a liquid. Liquid crystals, therefore, have a short-range order, like a crystal, and a long-range disorder, like a liquid.
Temperature-sensitive liquid crystal material is cholesteric—that is, arranged so that the long, rod-shaped molecules sit side by side in layers, with each layer at a slight angle from the layer above and below it. You could picture this arrangement as a spiral staircase, with the molecules as the risers in the stairs.
When the liquid crystal is heated, two things happen. First, the layers move farther apart. Second, the angle between the molecules in each layer increases. These two changes combine to cause the spiral staircase of molecules to wind up tighter as the crystal heats up. As a result, at lower temperatures, the spiral matches and reflects visible light with longer wavelengths—red light. At higher temperatures, the spiral matches and reflects light with shorter wavelengths—blue light.