One of the rules of astrophotography is that clouds always position themselves right over the objects you are trying to shoot. When the subject in question is a pair of planets, then a cloud will always cover one or the other planet, making it impossible to capture both at once and therefore record the conjunction.
Tonight, March 15, I chased out west of Calgary to get the conjunction of Mercury and Jupiter over the scenic skyline of the Rockies. Of course, clouds drifted slo-0-0-0-w-ly across the sky. But with a little patience (and I do have very little to spare in situations like this!) I was able to catch a few moments when both Jupiter (at left here) and Mercury (upper right) shone in view amid the clouds.
The highway (Highway 66 to Bragg Creek) adds a nice touch, with cars seeming to come and go from the distant planets.
Again, as with the previous night’s shot, this is a “high dynamic range” stack of three shots taken in quick succession but with EV values 1 1/3rd f-stops apart, to retain both ground and sky detail in an inherently contrasty situation. Photoshop CS5’s HDR Pro feature does a great job. This is with the Canon 7D and 135mm lens.
– Alan, March 15, 2011 / Image © 2011 Alan Dyer
The Amazing Sky 