text: The size of this effect is difficult to quantify: the Intergovernmental Panel on Climate Change estimates that the global mean radiative forcing for black carbon aerosols from fossil fuels is +0.2 W m−2, with a range +0.1 to +0.4 W m−2.Black carbon is a bigger cause of the melting of the polar ice cap in the Arctic than carbon dioxide due to its effect on the albedo.Astronomical albedo In astronomy, the term albedo can be defined in several different ways, depending upon the application and the wavelength of electromagnetic radiation involved.Optical or visual albedo The albedos of planets, satellites and minor planets such as asteroids can be used to infer much about their properties.The study of albedos, their dependence on wavelength, lighting angle ("phase angle"), and variation in time composes a major part of the astronomical field of photometry.For small and far objects that cannot be resolved by telescopes, much of what we know comes from the study of their albedos.For example, the absolute albedo can indicate the surface ice content of outer Solar System objects, the variation of albedo with phase angle gives information about regolith properties, whereas unusually high radar albedo is indicative of high metal content in asteroids.Enceladus, a moon of Saturn, has one of the highest known optical albedos of any body in the Solar System, with an albedo of 0.99.Another notable high-albedo body is Eris, with an albedo of 0.96.Many small objects in the outer Solar System and asteroid belt have low albedos down to about 0.05.A typical comet nucleus has an albedo of 0.04.Such a dark surface is thought to be indicative of a primitive and heavily space weathered surface containing some organic compounds.The overall albedo of the Moon is measured to be around 0.14, but it is strongly directional and non-Lambertian, displaying also a strong opposition effect.