Mapping the infrared thermal emission from the surface of Venus, 2017 April-May

2017 September 21

Richard McKim

Employing a novel narrow-band filter technique, Australian BAA observers Phil Miles & Anthony Wesley have been able to achieve a new level of resolution for amateur imaging of the infrared thermal emission from the nightside of Venus. In addition to revealing topographic details, images from 2017 April-May reveal at least one compact, infrared-bright spot located within a topographic depression upon the surface.  We discuss the interpretation of this bright spot, and the question of whether it was or was not a temporary feature.

Introduction
Ever since the eastern elongation of 2004, amateur astronomers have succeeded in taking images of the infrared thermal emission (IRTE) from the nightside of Venus. Since temperature decreases with height above the surface, the infrared albedo gives a measure of altitude, and earlier results are known to correlate well with Magellan spacecraft altimetry. We show two examples of such work and comparison mapping in Figures 1 and 2.

However, the maps produced from our ground-based images at each successive inferior conjunction have shown unchanging features – until now. At the 2017 western (morning) elongation, Venus was well placed for southern hemisphere observers, and Phil Miles & Anthony Wesley (Figure 3) teamed up to try to obtain still better resolution of the features visible by means of the IRTE….(continued)

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