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Sunday, August 8, 2010
Four planets at sunset
Click image to enlarge.
There's a glorious spectacle in the Western sky at sunset for the next few days. You can see four planets in the gloaming with the unaided eye in one field of view. Here they are: Earth (in the foreground), Venus, Mars, and Saturn. Mars and Saturn are just subtle pixels in the reduced image above—click it to enlarge. The image has been processed to approximate the appearance to the dark-adapted human eye. If you have a view all the way to the horizon and look a bit earlier, you may be able to spot elusive Mercury below and way to the right of this grouping (almost directly West on the compass). With the Jura mountains obscuring the horizon at Fourmilab, the western sky remains too bright to glimpse Mercury until it has set behind the mountains. This picture was taken at 19:31 UTC on 2010-08-07 with a Leica M9 digital camera with a Noctilux 50mm lens at f/0.95, 1/45 second exposure, and ISO 160 sensitivity. Trees in the foreground are out of focus due to the minuscule depth of field of the Noctilux at full aperture, but then you're looking at the planets, aren't you? Your Sky provides this view of the horizon at the time this photo was taken. No, Venus isn't really pink. There's a bit of residual colour in the Noctilux wide open, and the M9 has no anti-aliasing (or, to be more precise, blurring) filter, so pixels that come through the lens and hit the sensor are rendered precisely as they land on the photosites of the detector. This is why some people love the M9 and some detest it. Put me down in the first column—just give me the raw sensor data—I'll fix it in the processing phase and be glad not to have to undo adjustments by some robot trying to improve on what the camera captured. But then, I still drive a manual transmission car. We're four days away from the Perseid meteor shower in a moonless sky. Here's wishing for good weather.Posted at August 8, 2010 00:26