Posted on 25/02/2015 by emily
CometWatch 20 February
Today’s CometWatch entry is a single frame NAVCAM image obtained on 20 February from a distance of 118.5 km from the centre of Comet 67P/Churyumov-Gerasimenko. The image has a resolution of 10.1 m/pixel and measures 10.3 km across.
The image nicely complements that published on Monday, this time showing the comet’s small lobe to the right and the large lobe to the left. Some 80 km closer than Monday’s image, details on the comet nucleus are now a little clearer again. For example, the smooth Imhotep region on the large lobe at the far left can be distinguished from the adjacent terrain of Ash, while on the small lobe the cliffs of Hathor stand out (refer to the regional maps here and here if you are unfamiliar with the comet's regions).
Rather captivating is the shadow of the larger lobe that is projected onto Hathor. The silhouette of the ‘underside’ of the comet can also be seen against the diffuse nebulosity to the lower-left of the nucleus. Around the sunlit portion of the nucleus, the nebulosity of the comet’s innermost coma can be seen together with denser streaks that likely correspond to regions of greater surface activity.
As usual, background features are typically a mix of detector noise, stars, and material ejected from the comet.
The original image is provided below: