source: Reflection nebulae are usually blue because the scattering is more efficient for blue light than red (this is the same scattering process that gives us blue skies and red sunsets).
target: Reflection nebulae are usually blue.  This is because the scattering is more effective for blue light than for red.
references: Reflection nebulae are usually blue.  This is because the scattering is more effective for blue light than for red. Nebulae's reflections are usually blue because blue light can  scatter more efficiently than red. This is the same scattering process that gives us blue skies and red sunsets. The reason the nebulae are blue is because it is easier for blue light to scatter. Reflection nebulae are usually blue because the light scattering is more efficient than red. Reflection nebulae are blue most times because the light moves better for blue than red (this is the same thing that gives us blue skies and red sunsets. Reflection nebulae are blue because it is more efficient to scatter blue light than red. This scattering is what creates blue skies and red sunsets. Reflection nebulae are usually blue because the scattering is more efficient for blue light than red. This is the same scattering process that gives us blue skies and red sunsets. Reflection nebulae are usually blue because light scatters better when it is blue than when it is red, like what makes skies blue and sunsets red. Reflection nebulae are usually blue since the scattering is more efficient for blue light than red (this is why we have blue skies and red sunsets). Reflection nebulae are usually blue because blue light is more efficient than red.