Knowra Reflection nebula Reflection nebula A reflection nebula is an interstellar dust cloud visible because it scatters light from nearby stars. Its appearance depends on the illuminating stars and the cloud’s dust.
Rayleigh scattering : Scattering of light by particles much smaller than its wavelength, with shorter wavelengths scattered more strongly. It helps explain why reflection nebulae often look blue.
Interstellar medium : The matter and radiation occupying the space between stars in a galaxy. Reflection nebulae are visible structures within this larger environment.
Pleiades : An open star cluster in Taurus, also known as the Seven Sisters. Dust around its bright stars forms one of the best-known reflection nebulae.
Polarimetry : The measurement and analysis of the polarization state of light. Scattered nebular light can be polarized, constraining the geometry of illumination.
Planetary nebula : An expanding shell of ionized gas expelled by a dying, low- or intermediate-mass star. Despite its name, it is a stellar ejecta shell, not a dust cloud reflecting nearby stars.
Interstellar dust : Microscopic solid particles between stars, composed mainly of silicates, carbon-rich material, and ices. These grains scatter the starlight that makes the nebula visible.
Emission nebula : A cloud of ionized gas that emits light after energetic radiation excites its atoms. Unlike an emission nebula, a reflection nebula mainly redirects existing starlight.
Witch Head Nebula : A faint, blue reflection nebula in Eridanus illuminated mainly by Rigel. It is a clear example of a nebula lit by a star outside the cloud.
Interstellar polarization : The polarization of starlight produced by aligned dust grains in interstellar space. Comparing it with nebular polarization helps distinguish scattering from dichroic extinction.
Supernova remnant : The expanding debris and shocked surroundings left by a supernova explosion. Its glow is powered chiefly by shocked or energized gas rather than reflected starlight.
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