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A Reflection Nebula The bluish hazy patch nestled in the prominent pink surroundings of the Lagoon Nebula is in fact a small reflection nebula — a cloud made of dust and gas that reflects the light of the nearby stars. The energy emitted by the bright central star’s is not strong enough, given the star’s distance from the nebula, to warm the gases to the point where they emit light of their own — as in an emission nebula, like the bulk of the Lagoon nebula. However, the star is still powerful enough to illuminate the cloud and make the dust visible. The nebula glows primarily by light reflected from the star and does not emit any light of its own. This reflection nebula appears blue for the same reason that our sky does. Most of the red, longer wavelengths of sunlight pass straight through the Earth’s atmosphere. However, much of the blue, shorter wavelength light is scattered by the gas molecules and fine dust particles in the atmosphere, and thus our sky looks blue. This same process occurs in the small reflection nebula. Blue starlight is scattered by tiny grains of dust in the interstellar medium more efficiently than red, so more blue light comes our way.
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