My Transit of Venus, 8 June 2004
You couldn't have asked for better weather for the transit. The day before was dominated by thick clouds, and I spent the night comparing various weather forecasts. But on the day it was bright, sunny and above all, clear.
Transits occur when a planet crosses the face of the Sun as seen from Earth. Naturally, a planet has to be between Earth and the Sun for this to happen, and so transits are limited to Mercury and Venus. As the orbits of these planets are tilted with respect to Earths orbit, we will see Mercury and Venus cross the Suns face rarely, as most of the time the planets will cross above or below the Sun. Transits can only be seen when the planet is between the Earth and the Sun at the same time as the planet is crossing the plane of Earths orbit. For Mercury, this occurs roughly 13 to 14 times a century, and for Venus, roughly every 100 years. So transits are relatively rare phenomenon, and quite interesting to watch.
Unlike the Mercury transit of last year, I turned up well before the event, and was able to share a cup of tea with my beloved, play a bit with the baby AND set up my multiple pieces of equipment. Our Venus viewing vistors arrived at various times during the event, and we were able to enjoy a rare event with tea and cinnamon cake provide by my beloved.
I used three methods to follow the transit. My 4" reflector with a solar aperture filter, telescope projection using my 50 mm refreactor and straight projection using a pinhole projector. I used the relector telescope to take the pictures you see below. The refracor telescope projection was quite successful, especially for several people corwding around wanting to see the transit at the same time. Unfortunatly the dust on the 25 year old lens came up too, obscuring the sunspots. The pinhole projector method didn't work too well, you need to project the imahe a fair distance to get a decent sized image, and as I was using the poll fence to stabilize the cardboard tube I was using, sun relections from the pool messed up the image. I also had a SLR camera with attachement for phorographing through the telescope, a home made CCD cam and a ordinary camrea for photographing the projection images, pity I didn't put film in the ordinary camera.
First contyact showed a clear "bite" from the Sun and I called everyone over. The entry of Venus onto the Solar disk was a relatively leisurely affair, and everybody was impressed as the bite from the sun grew bigger and rounder. I was creating a bit of a mess by swapping from film camera to webcam to eyepiece (so the vistitors could see high power views not available with the projection system; memo to self, get more telescopes) with refocussing for each system. Nonetheless, I managed to take halfway decent photos AND impress the visitors, but my timing records were shot.
As with the Mercury transit I just missed the black drop effect. This is when Venus is just crossing into the sun, and it looks as if there is a trail or drop joining Venus to the Suns edge. This time it was because my beloved was viewing Venus as it happened, as she was thrilled, I didn't care. Aparently it wasn't very pronounced this time, as other observers reported that it was absent or hard to see. However, I did see the crisp black circle of Venus separated from the Suns edge by a hairline filament of light, which was absolutely beautiful.
The transit progressed, the kids pointed at the black dot of Venus on the projection screen and ran around a lot, the vistors drank more tea and cake and remarjed that seeing Venus crossing the Sun put the Earth into more of its cosmic perpective. The Sun lowered towards the horizon. I was able to follow the transit for most of the time. I took my last photo at 4:18 pm, then clouds moved in.
|approx 2:39 pm ACST, Venus has just entered the Suns limb||approx 2:45 pm, Venus is about half way into the Suns disk|
|approx 2:50 pm ACST, Venus is close to exiting the Suns Limb||approx 2:55 pm, Venus is about to fully enter the Suns disk|
|2:57 pm ACST Venus is just within the Suns disk||3:15 pm, ACST Venus is even further into the Sun|
|approx 2:40 pm ACST, Venus has just entered the Suns limb||approx 2:50 pm, Venus is about to fully enter the Suns disk|
|3:17 pm ACST Venus well within disk||4:18 pm, ACST Venuseven further in the Sun|
Technical guff. The solar filter was a full apature Identi-View SVD 4.5 filter from Astro-Optical Supplies (thanks) fitted to a York Optical Skyrover 114 mm Newtonian reflector. The webcam images of the transit were taken with a connectrix web cam as AVI's using VEGA and stacked using Astrostack. The photographs of the Transit were on Fujicolor X-TRA 400 colour print film via 2x Barlow projection (no-name Barlow lens) and a Pentax KM SLR camera body with T adaptor. Exposures were 1/125 and 1/60 of a second. Images were scanned at 300 dpi using an Olympic Technology scanner, and cropped with Photoshop.
The web cam images are somewhat dissapointing, and don't show up the detail in the pictures. This is partly due to difficulty in foccusing the webcam with the laptop screen partly obscured by sunlight and some bluring due to atmospheric turbulence. The spot that is Venus is fuzzy in the webcam images, but was crisp and black in the eyepiece at low magnification, and wobbly at high magnification due to atmospheric turbulence.
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Created:Tuesday, 8 June 2004, 11:22:32
Last Updated: Thursady, 17 June 2004, 11:22:32