Korea Trip - Part 5

Transit of Venus

We planned our Korea trip to include observing the transit of Venus, an extremely rare astronomical event. Venus crosses the face of the Sun only twice a century! It won't happen again for another 105 years. Here's a diagram showing how this June's transit transpired.

I've been lucky to observe both transits this century, one in 2004, and the latest one just a few weeks ago. Neither was fully visible from Virginia, so I traveled long distances to view them. In 2004 I went to Italy with an astronomy tour group to observe the entire transit in perfect conditions from a site north of Rome.

Viewing the transit in Italy while wearing my special transit t-shirt

Conditions in Italy were absolutely perfect - clear, totally cloudless skies for the entire transit duration. Unfortunately, conditions were not so perfect for viewing the 2012 transit from South Korea. On June 6th, transit day in Deokpo on Geoje Island, the sky was covered with high, hazy clouds. Of course, with my typical astronomical luck, the sky was clear the day before and most of the day after. On June 6th the Sun was bright enough to show through the milky whiteness at times, but it was never entirely free from obscuring hazy clouds.

Around 6:30 am local time I gathered equipment and went to the roof of my daughter's 10-story apartment building. I hoped to use a mylar filter with either Keegan's binoculars or his camera. I also had my pair of 10 X 25 Coronado solar binoculars. First, I unsuccessfully tried Keegan's binoculars. It was impossible to steadily hold the filter in one hand and the binoculars in the other. The Coronado binoculars worked best, although the Sun frequently looked fuzzy through clouds. At about 7:20 am I first detected the black presence of Venus entering the Sun's limb. Soon after I attempted a photo using Keegan's Canon EOS Digital Rebel XTi equipped with a 300 mm telephoto lens. The camera was mounted on a good quality tripod, but I had to manually hold the mylar filter in front of the lens. It was extremely hard to focus. Here's the disappointingly fuzzy image I captured soon after Venus appeared on the Sun.

1/13 sec exposure at f/11 with 300 mm telephoto lens at 7:23 am

The mylar filter purposely blocks most of the Sun's light. It passes only a small portion in the blue end of the visible spectrum. Thus, my images have a blue-purple color. After Venus had fully entered the Sun's disk I tried another picture. Again, the image isn't sharp because hazy clouds masked the Sun. Focusing was very difficult.

1/10 sec exposure at f/14 with 300 mm telephoto lens at 7:46 am

The last image here is the best of my efforts. Clouds thinned briefly allowing better focus. Venus is sharper and three sunspots are barely visible. The sunspots look like tiny dark specks arranged along a line starting at Venus and proceeding diagonally downward to the right. The exposure time could probably be improved, but there was no time to try variations because clouds closed in again.

1/80 sec exposure at f/5.6 with 300 mm telephoto lens at 10:59 am

I didn't use my solar telescope to observe this event because it would have required hauling four big equipment cases and my laptop to Korea. I couldn't imagine putting this expensive equipment at risk on the long journey. Perhaps modern scientific observatories render amateur viewing on location obsolete. For example, magnificent instruments in the Solar Dynamics Observatory satellite continuously observe the Sun without any atmospheric interference. Images from this satellite are available to anyone, and the image quality far exceeds that of my pathetic images above. Here's just one example:

Transit image from the Solar Dynamics Observatory (Click for full detail.)

Astronomical observing is often a struggle. Obstacles abound. Unobstructed viewing space on the apartment roof was limited. Numerous wash lines strung across the roof blocked the view. When the Sun neared the zenith my attempt to observe from a horizontal position on a beach chair was blocked by a drying blanket flapping in the breeze above me. As noon approached the Sun was so near the zenith the camera tripod could not point towards it. I stopped watching at about 1:26 pm. Thickening clouds prevented viewing the egress. Nevertheless, it was a thrill to view this event, even under less than ideal conditions.

Finally, I can't resist including something from a talk I once gave to an astronomy group before the 2004 transit. In June of 1769 an astronomer with the astounding name of Maximilian Hell observed a transit of Venus from the island of Vardo off the coast of Norway. By a remarkable coincidence a total solar eclipse followed only 6 hours after the transit! Hell also observed this eclipse! When I read about this unlikely and spectacular pair of events it got me thinking about events that would be even more unlikely, but much more spectacular. Imagine the following sequence of astronomical wonders:

• The sky is completely clear on transit day and the Sun is covered by several huge complicated sunspot groups as well as many filaments and big prominences along the solar limb.
• Venus AND Mercury transit at the same time!
• Shortly after the planets transit a total solar eclipse occurs! When the solar corona becomes visible during totality both Venus and Mercury are visible against the bright coronal background!
• During the darkness of the total eclipse a beautiful comet (previously unobservable because of its proximity to the Sun) becomes visible near the Sun!
• An auroral display becomes visible in the north while totality proceeds in the south!
• A massive sporadic meteor shower with hundreds of meteors per minute becomes visible during the darkness of totality! 

Imagine astrophotographers frantically trying to capture images of all these wonders! Afterward they have ice cream.