Venus Approaching Transit

As we approach the Transit of Venus I decided to attempt to photograph Venus as a very thin crescent. I do not normally pay much attention to the planet, it is pretty when seen in the sunset. But when you turn a telescope to Venus it is quite boring, a white ball with no detail to be seen. I find I have been paying a bit more attention with the transit looming close on the calendar.

I could photograph the planet after sunset, but as Venus is quite near the Sun it would be very low in the sky and I would be shooting through a lot of air to get the imagery. Atmospheric distortion would be a major problem. The other method is to try something I had not done before, photograph the planet in the daytime, high in the sky and quite near the Sun.

Imaging Venus in the Daytime
Imaging Venus in the daytime a mere 12°44' from the Sun.
Don’t try this at home?

Yeah, This will be a tricky operation. Venus will be only 12°44′ from the Sun, meaning I will have to be quite careful to avoid roasting my equipment, or my eyes.

I chose to use the 90mm APO refractor. With the optics at the front there will be some sunlight splashed down the interior of the tube. It should not be a focused image as it will hit the tube not even halfway down. There the heavy aluminum tube walls should dissipate the heat efficiently. The fully baffled tube should also stop much of this light before it reaches the camera. I may not have designed and built the optical tube with this sort of abuse in mind, but I did build it heavy, it will take it.

Venus 28May2012
Venus on 28May2012, about 12°44' from the Sun
I located Venus by centering the Sun with the solar filter on the ‘scope. I then adjusted the setting circles and offset to the correct coordinates for Venus. After a visual safety check I removed the solar filter for a look. And there it was, a graceful and very thin crescent shining brightly against the blue sky. Replacing the eyepiece with a camera I focused and shot several video sequences.

The results? The final image can bee seen to the left. Not horrible, but it could have been better. The seeing at 11am was already starting to degrade, I am always amazed at how well the software can extract a half decent image from such distorted original material. The magic of sorting through and averaging a thousand frames. I wonder what I could do with better seeing.

Another try? Probably not, Venus is quickly getting closer to the Sun as we approach transit in nine days. The next time I photograph Venus it will most likely be silhouetted against the solar disk. Maybe an attempt after transit? I could shoot earlier in the morning with possibly better seeing.

Author: Andrew

An electrical engineer, amateur astronomer, and diver, living and working on the island of Hawaiʻi.

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