Steven and Neville, I am addressing this to both of you, since I am not sure who wrote the two pages cited by Steven, below, and you are both maintainers of the site and presumably agree with its content. First of all, I would really like to recommend that you adopt a new rule of your lives; To always go to the original source before making conclusions about things you see in the media. You have to realize that what ever you tell a journalist, even when handed a written press-release, they will make up their own story, only loosely based on what you told them. Okay - and now to the picture of Comet Wild 2. You can find all the details at http://stardust.jpl.nasa.gov/news/news97.html The picture is obviously not what you think it should be. It is a composite (and NASA clearly states that) of the surface of the comet, and a much longer exposure to reveal the faint coma. The latter is colour-coded yellow, to avoid ambiguity. The coma is so weak/faint that it wouldn't show up on an exposure that didn't over-expose the surface of the comet - therefore the composite. There is nothing dubious about that. To address the other points you raised: Ad. 1) The "halo" is not strange - it's a comet, comets have comas. This comet is far from the Sun so the coma is very weak. Ad. 2) It's just an imperfect transition between the two different exposures. it actually helps separate the two (surface and coma-exposures). It is most likely due to the small change in viewing angle between the two exposures. Ad. 3) Colour coding of the coma exposure. Ad. 4) Because the space probe was programmed to perform autonomous tracking of the comet to always centre it. The tracking is done with a scanning mirror, since moving the whole telescope would be too slow. Speeding past at 6.1 km/s at a distance of 240 km, the angle between spacecraft and comet would only change by (6.1km/s) / (240km) * (180°/rad)/(pi rad) = 1.46°/s The longest standard exposure was 20s (=> 29.1° change), but being so close they could probably use a much shorter exposure. This change in viewing angle, during an exposure, probably accounts for the slight blur that we do see. Also, the camera is just a navigation camera - it wasn't optimized for science duty - but it obviously did a great job! See JPLs page for details: http://stardust.jpl.nasa.gov/mission/camera.html Ad. 5) Shutter speed addressed above, the aperture is 57mm. The angular speed of 1.46°/s is really not that impressive, and something you would easily encounter on Earth - e.g., a runner 90m away - not extra-ordinary at all. Ad. 6) I have experience with soldering and, being generous, I would say the resemblance is very weak. See here for more stunning pictures http://stardust.jpl.nasa.gov/photo/cometwild2.html Remember that this is a micro-gravity world with a very "lumpy" field of gravity (due to the large craters and general non-round shape of Wild 2), so landscapes do not behave as here on Earth. Steve, I haven't seen a response from you to my post of 24.01.2008 //www.freelists.org/archives/geocentrism/01-2008/msg00123.html about what you referred to as "Odd happenings on (Mars?)". At least some acknowledgment that you have read it would be appreciated. Regner Steven Jones wrote:
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