Astronomers using the Subaru Telescope on Maunakea have measured the characteristics of mid-infrared light from an old comet nucleus. The comet, originally detected by the Pan-STARRS survey telescope on Haleakalā, passed quite close to the Earth and the team managed to observe it just a day before its closest approach. Besides measuring the size of the nucleus (about half a mile across), they showed that the mid-infrared glow was characteristic of tiny sand-like grains, of a particular type which are better known on Earth as talcum powder. Interestingly, they showed that the grains had been heated to more than 330°C or 600°F (about the temperature of a pizza oven) in the past. This can be explained if the comet’s orbit once passed much closer to the Sun than it does now, and provides a hint into how comets age. These observations were uniquely suited to Maunakea as the conditions on the mountain are especially well-matched to infrared astronomy.
Read more, in the Subaru Telescope press release.