Tuesday, March 31, 2009
Two Crescents, One Vista
There is nothing quite like seeing a very young crescent Moon in the same vista as the super-bright diamond of Venus. Although this February 26th conjunction shot shows the two planetary bodies close together, it does not convey what I saw. In fact, no photograph can really capture it, since the blazing gem of the cloud-shrouded planet will over-expose itself into a big dot near the Moon with its dim Earthshine. Even HDR cannot help, since a properly-exposed Venus would disappear into a few pixels' worth of image, hardly conveying the brilliance of the Evening Star.
The best we can do is to take two properly-exposed photos and enlarge them. The Moon is about what one would expect for the infant phase, as it dipped into a bit of horizon fog that evening:
But the surprise comes with the enlarged view of Venus. The extra February brightness is coming from a planet that is sporting a relatively thin crescent:
How can this be? Why does Venus get brighter as its crescent gets narrower? The mystery is explained here.
By the way, Venus completes my collection of planetary disks that can be captured with an ordinary telephoto lens. (See the Astrophotography With a Camera and Tripod blog posting.) Someday I plan to make a composite image that shows: The Moon, Venus, Mars, Jupiter with its moons, and Saturn with its rings.
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