Venus looks more boring than you think it does
Posted by Emily Lakdawalla
21-09-2009 12:54 CDT
The MESSENGER team posts one captioned image per week from their previous encounters. These have mostly been of Mercury but once in a while they toss in an image from one of their two Venus encounters, which happened on October 24, 2006 and June 5, 2007. Today's was this view revealing Venusian cloud features. It's a bit unusual in that genre, because most of the time when you see a picture of Venus with cloud features, it was taken through an ultraviolet filter; the clouds are streaked with some as-yet-unknown "UV absorber" that really makes their shapes pop. This image, by contrast, was taken through a red filter; it's a testament to the fine quality of MESSENGER's camera that so much detail is visible at this wavelength.Nearly every image of Venus that is in the public domain has been processed to enhance the subtle details in clouds. But if you were flying near Venus, you'd likely see none of that. What you'd see is this (assuming you were wearing dark glasses -- Venus would be almost unbearably bright to our eyes): Yes, that's a true color view, composed of red-, green-, and blue-filter images. Venus is brilliant, but very very bland. Which is why montages like this one are a pet peeve of mine: All the planets are shown as they appear in natural color, though the contrast and saturation have been goosed a bit to make them more dramatic. Except for Venus. The view of Venus is based upon Magellan radar images that penetrated the clouds, and on top of that they were colorized that garish orange color.
So if you're going to make your own planet montage, avoid the Magellan images, and avoid the equally garish Pioneer and Galileo ultraviolet-filter views like this one.Instead, consider using one that shows Venus more as it would appear to a spaceborne observer. I think this view is a nice compromise. It shows some cloud features with slightly enhanced color, but still gives the impression of Venus as a thickly cloud-shrouded world. Speaking of MESSENGER, it's on course for its third flyby of Mercury on September 30, a week from Wednesday. I have been pestering the team to get a hold of their science plan for my usual preview timeline story, but don't have it yet. They just announced this morning that there'll be a press briefing this coming Wednesday about their plans, which I will of course be watching and reporting on. In the meantime, they've posted some preliminary planning information here.
Or read more blog entries about: