Transit of Venus

Venus transitted the sun today. This means that the planet Venus passed in front of the face of the sun. This is a rare event, it happens in pairs a little over a century apart (the second of this pair is in 2012, and the one after that is in 2117).

A transit is not, it has to be said, visually spectacular. One would not know it was happening unless special steps were taken.

Historically, a transit is an important event as observations from a variety of positions, accompanied by accurate timing information allows us to measure the distances in the Earth/Venus/Sun system, and hence obtain the size of the solar system.

Today, the transit I am told, will be used to give information about volcanism on venus. In any event, it is a humbling thing to see Venus dwarfed by the sun, given that Venus is not dissimilar in size to the Earth.

I used a refracting telescope in a darkened room to view the transit. The telescope projected an image which was getting on for half a metre across. A screen was constructed so that sunlight which missed the telescope would be blocked.

There were a few minor sunspots visible, but one had to look hard.

Though I've only shown the telescope images, reasonable results were also obtained with binoculars, the image so formed was about 10cm in diameter.

A closeup of Venus in Transit
This is a close up image of Venus in transit across the sun.

The whole face of the sun
This picture shows the entire face of the sun projected onto a screen. The horizontal line is a join in the paper where we constructed the screen.

A comparison to the pinhole camera method
As the sun moved through the sky, we had to keep adjusting the alignment of the scope. This is a picture taken just before such an adjustment.

Here I am....
This picture shows me next to the projected image of the sun.

In one of the above pictures, there is a bright dot on the screen. The dot is an image of the sun formed when some light sneaked past a small chink in our screen. It's actually, several images overlapping. This is effectively forming a pinhole camera, or rather several pinhole cameras. It shows how inadequate the pinhole camera is compared to a lens based effort.