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Saturday, August 07, 2010

Planetary triangle, 8/7/2010

For previous nights see these entries:

Planetary line-up at sunset (Introduction, with Jack Horkheimer videos)
Planetary triangle, 7/29/2010
Planetary triangle, 7/30/2010
Planetary triangle, 7/31/2010
Planetary triangle, 8/5/2010
Planetary triangle, 8/6/2010

Observational astronomy is a hit-or-miss proposition. Will the sky be clear? Will humidity cause a milky translucence in the air? Will a flotilla of clouds show up and cover over the trio of planets you're trying to photograph just as it's getting dark enough to see them clearly?

This evening the answers to those questions were yes, no, and yes.

I got to my house earlier than I had planned and set myself up in bright twilight. I tried to aim my camera in a direction where I would see the planets just as soon as they appeared, and where I would be able to see the planets as they sank beneath my grapevine horizon, all without having to move the camera. I took my first image at 8:32 PM:


Here bright Venus is clearly visible, but even doing terrible things to the brightness and contrast on this image I am not able to tease out Mars or Saturn. They do not show up on the series of photographs I took until twelve minutes later, at 8:44:


You probably can't see them in this photo, even on the enlarged version. But trust me, they were there in the full-sized original. Here's a crop showing just the three planets. Venus is at lower right, Mars is at upper left, and Saturn is at upper right.


Previous photo sessions have all started after 9:00 PM. But the sad fact is, the Sun is setting earlier and earlier as days are getting shorter and nights are getting longer. (Which is good news for backyard astronomers like me.) Venus was rapidly heading for the grapevines and I was concerned that it would be obscured by them before the sky was dark enough to clearly image the planetary trio. I needn't have worried, as I should have realized when the clouds began rolling in at 8:53.


Things rapidly went from bad to worse. Within three minutes the clouds were beginning to obscure Mars and Saturn. I took my last useful image at 8:56 PM:


Once again you might not be able to see the dimmer planets in this image, so here they are in an enlarged crop - once again, with Mars in the upper left, Saturn in the upper right, and Venus in the lower right.


And that was the end of that. Clouds reached up and covered Venus. I had to take a break at this point, and packed up my camera and tripod and headed indoors. I knew I had spoiled any chance of directly comparing later shots to these earlier images, but I had a feeling I was done observing for the night. When I peeked outside five minutes later my assumption was confirmed. The clouds which had only been covering the planets low in the West now extended to the zenith of the sky. Whether they had blown in from the West or had condensed out of the moisture in the air, I don't know. But whatever had happened, I was done.

Tomorrow night, Sunday August 8, is the closest gathering of these three planets for this conjunction. Will I be able to see and photograph it? We'll find out then!

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