Venus Transits the Sun

Eight years ago on June 8, 2004, I woke up well before dawn and carted my solar telescope to an open field with a view of the eastern horizon. The Sun would rise at about 6 AM, and when it rose, the first transit of Venus across the Sun in more than one hundred years would be almost over. The third contact (when Venus starts to pass out the disk of the Sun) would begin at 6:06 AM, and the transit would be over by by 6:26 AM.

As it happened, I was not able to observe any portion of the transit. By the time the Sun rose over the treetops on the distant shore of the lake, it was already 6:30 AM. Game over.

Fortunately, transits of Venus occur in pairs separated by enormous gaps in time. I had only to wait a trivial eight years for my second (and last) opportunity to view a transit of Venus. The great event took place this past Tuesday afternoon, starting at 5:06 PM CDT. I planned for the occasion and watched the weather with an uneasy eye. When the day came, the heavens cooperated with a cloudless skies and a mild temperatures. I was able to set up the solar scope half-way down the driveway and watch the most impressive parts of any transit--from the moment when the small black dot of Venus first begins to chew into the bright disk of the Sun all the way through at least half of the entire six-hour event.

My solar telescope is actually the best use of the little 60mm telescope that served to introduce my family to observational astronomy. These "beginner" telescopes are too often scorned by amateur astronomers. It is true that they are advertised as having unrealistic and unusable high magnifications of 300X or more. At those magnifications they provide dim views on very shaky mounts. But if one uses a fairly good 25mm eyepiece (which can be salvaged from an old pair of binoculars), a 60mm scope can be very satisfactory for most low-magnification observing.

My Solar Telescope (with its filters)

The Moon and the Sun are examples of objects that are best observed at 30X or less. The relatively long focal length and small objective lens of a beginner scope provide excellent resolution without excessive brightness while imaging the Moon. The Sun, of course, is far too bright to be observed without the use of solar filters. Thus, I made my own solar filters using a pair of free solar sunglasses, the ones with card-stock frames that came many years ago as an insert within a copy of
Astronomy magazine. The downside of doing this is that I needed to stop the objective lenses of both the 60mm main tube and the 50mm finder down to a mere 25mm--even smaller that the 37mm of Galileo's first telescope in 1609.

The photos below show the basic setup. The images we were able to see through the scope were much better than the ones I captured by holding a digital camera up to the eyepiece. In fact there wasn't much difference between what I saw and the high-quality photo at the top of this blog. At one point I counted fourteen sunspots.

Jeff observing the transit

Sue observing the transit

Venus first digs into the Sun

Venus fully within the Sun's disk