Various types of stars have dust around them. In the well known case of the Pleiades the dust around the stars is unrelated to the stars, and is instead dust from an interstellar cloud that the Pleiades cluster has drifted into on its way through the galactic disk. ... The dust in interstellar space is observed in a variety of ways: due to its passive absorption of starlight ("extinction"), by its production of polarization in starlight, and then at long wavelengths due to its thermal radiation. ...