Sky & Telescope October 2004 [antikvár]

by richard tresch fienberg jFrom Venice to Venusi had to choose my topic for this column before traveling to Italy for the June 8th transit of Venus across the Sun (see page 140). Three centuries ago, Edmond Halley described such an event as "by far the noblest [sight] astronomy affords." Back in May, though, I was convinced that, from a purely aesthetic perspective, 13-year-old Roxana Bell daughter of science writer Trudy E. Bell offered a more apt description of what I would see: "Just a dot!" So on my editorial-assignment sheet, I put down the working title "Ttanzzzit of Venus." Honestly, I expected to be bored.I'll admit I was wrong. I experienced many strong feelings in Italy, but boredom wasn't one of them. Let's start with the setting. My Sky Teie^cope/TravelQuest International tour group had already spent a few days in and around magical Venice. Then, thanks to the gracious hospitahty of the staff of the Arcetri Astrophysical Observatory in Florence, we were allowed to set up on the facihty's terrace overlooking the lush Tuscan countryside. The sl^ was deep blue and cloudless. In the distance, we could see the tile roof of the villa where Galileo Galilei spent his final years under house arrest. The warm spring air was ripe with fragrance and birdsong. Transit or no, this was going to be one fine day!I wasn't all that excited about the transit of Venus until I actually saw it in Italy.Watching through my white-Ught-filtered Tele Vue-85 refractor at 150x, I strained to catch the moment when Venus first began to dimple the Sun's limb. Right on schedule, there it was. As the planet crept more fully onto the solar disk, I could perceive the "ring of hght," the effect of sunlight refracting through Venus's thick atmosphere (June issue, page 73). It was subtle but unmistakable, and it meant I could see the planet's entire round outline while part of it was still beyond the Sun's limb. Beautiful!like others who observed with quahty equipment, I didn't see the "black drop" as described in centuries past (September issue, page 92). I did see some daik "fuzz" between the solar and planetary hmbs, and at times I perceived a razor-thin hne connecting them, but Venus never took on the shape of a drop of water.Once the planet was well onto the Sun, It was, as Roxana had predicted, "just a dot." But, oh, what a dot! I knew It covered less than a thousandth of the Sun's face, but it looked huge! I thought of one of Galileo's first sketches of the Moon as seen through his telescope. It shows a crater much larger than any we can see. His drawing records the impact on Galileo more than on the Moon Itself. If I were to draw you a picture of the transit, I'm sure I'd depict Venus much bigger than it really was, too.As Venus exited the Sun, I watched through my Coronado hydrogen-alpha filter. Because this Instrument shows the chromosphere overlying the Sun's visible face, I could still see the planet for several minutes after my fellow observers lost it from view in white hght. By then I was eager to milk every last second out of the event.Having witnessed the transits of 1761 and 1769 and contracted a fatal disease during the latter, Jean-Baptiste Chappe d'Auteroche declared, "I have fulfilled my aim, and I die content." I'm not there yet. Although many newspapers and magazines mistakenly described last June's transit as a "once-in-a-llfetime experience," it wasn't - at least not for those of us who hope to stlU be around on June 6, 2012. That day will bring another - the last untU 2117 - and I want to see it. Should I go to Point Venus in Tahiti, where Capt. James Cook observed the 1639 transit? That would certainly be poetic. But from the South Pacific only part of the event will be visible. So maybe I'll go to the Australian outback, which seems to offer the best viewing prospects for the entire transit.All I know for sure is that I don't plan to miss that rare once-in-a-lifetime event that can actually be experienced twice!