"[T]he extended red emission (ERE) [is] observed in many dusty astronomical environments, in particular, the diffuse interstellar medium of the Galaxy. ... silicon nanoparticles provide the best match to the spectrum and the efficiency requirement of the ERE."
Def. the solid material thrown into the air by a volcanic eruption that settles on the surrounding areas is called tephra.
"[T]ephra, is a general term for fragments of volcanic rock and lava that are blasted into the air by volcanic explosions or carried upward in the volcanic plume by hot, hazardous gases. The larger fragments usually fall close to the volcano, but the finer particles can be advected quite some distance. ... [Fine ash] can contain rock, minerals, and volcanic glass fragments smaller than .1 inch in diameter, or slightly larger than the size of a pinhead."
- Adolf N. Witt; Karl D. Gordon; Douglas G. Furton (July 1, 1998). "Silicon Nanoparticles: Source of Extended Red Emission?". The Astrophysical Journal Letters 501 (1): L111-5. doi:10.1086/311453. http://iopscience.iop.org/1538-4357/501/1/L111. Retrieved 2013-07-30.
- Mark R. Mireles; Kirth L. Pederson; Charles H. Elford (February 21, 2007). Meteorologial Techniques. Offutt Air Force Base, Nebraska, USA: Air Force Weather Agency/DNT. http://oai.dtic.mil/oai/oai?verb=getRecord&metadataPrefix=html&identifier=ADA466107. Retrieved 2013-02-17.