New Scientist: When viewed from space, Earth reflects a lot of light in the near-IR wavelength because of the presence of chlorophyll in plants. As our ability to detect exoplanets increases, our telescopes may soon be able to detect similar reflections due to lifeforms on those planets. However, it is likely that most such planets will not be covered by leafy green plants. Siddharth Hegde and Lisa Kaltenegger of the Max Planck Institute for Astronomy in Germany examined the light reflected by more extreme areas of Earth, such as rocky deserts and acidic waters. They found that the color of the light reflected by those areas varied depending on whether lichen, algae, or bacteria were the dominant life form. Although similar reflections from exoplanets could be a potential sign of life, they can’t by themselves prove that life is present. Atmospheric interference and other factors could alter the wavelengths of light being reflected.