Spectral variation in the infrared emissivity of asteroid Steins derived from the March 2008 observations, compared to that derived from the November 2005 observations and to two laboratory measurements for enstatite and aubrite (Barucci et al. 2008). In the case of the March 2008 data, two spectra are represented, the nominal spectrum and an alternative spectrum incorporating a “teardrop” effect (see text).