Reddening is a phenomenon in astronomy where the apparent brightness and color of a celestial object, such as a star or galaxy, is affected by the scattering and absorption of light as it passes through interstellar dust and gas. This causes the object to appear redder and dimmer than it actually is, as shorter-wavelength blue light is more strongly scattered and absorbed than longer-wavelength red light. Reddening is an important consideration in astronomical research, as correcting for it allows scientists to better understand the true properties and characteristics of celestial objects.