Friday, July 30, 2010

Planetary triangle, 7/30/2010

My plan to photograph the ongoing conjunction of Venus, Saturn, and Mars nightly nearly got derailed on Night 2. Seeing conditions were nothing like yesterday. Even in the parts of the sky that were not full of clouds, a dim haziness made viewing conditions poor at best. Mars and Saturn occasionally emerged from the cover of some wispy clouds to shine faintly through the haze.

This picture was taken at 9:11 PM, twenty-four hours after the first photo in yesterday's post. Mars and Saturn are almost invisible in the reduced-size image above, and don't fare much better in the larger version you can see when you click on it.

Here's a version where I played with the contrast and brightness. Now the two outer planets are a bit more clear, and we can see that Saturn appears to have tipped forward a bit since last night, leaning to the right and toward Venus. In reality, neither Mars nor Saturn have moved very much in the past twenty-four hours - Mars takes 687 days to go around the Sun, while Saturn takes 29.7 years. Earth, on the other hand, has moved 1/365th of the way around the Sun since last night. (If you're having trouble visualizing this, just break out your trusty orrery and see for yourself - or play with the controls on this nifty online orrery until you can get it to show you the minuscule differences in position from one night to the next.)

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