Although I am interested in the nebular physics of PNs, my main interest is the dust in and around PNs. We normally observe the dust either from the mid-infrared spectra of PNs (see below) or by direct imaging. ... Image credit: NASA, ESA, and R. Ciardullo. I study the dust in and around PNs to see how it compares to the dust in evolved stars and proto-planetary nebulae . ... This spectrum was taken with the slit oriented along the bright bar of the nebula (see the PN images page ). ...