On June 8 Venus will take 6 hours, 12 minutes and 30 seconds to pass in front of the Sun. The last transit was 1882. Of course, where you stand, and how you protect your eyes from the sun's harmful radiation, are critical.

First, the obvious. You will only be able to see the transit during daylight hours. (See figure 3) If it’s nighttime in your part of the planet, you’re out of luck (sort of – see below).

Venus nudges against the east face of the sun at precisely 05:13:29 Greenwich Universal Time (that’s 5:13 a.m. in Greenwich, England). Astronomers call this first contact. In North America it means that when the sun rises Venus will already be more than half-way across our solar system's furnace, and by 7:25 a.m. EDT, will no longer be in front of the sun. If you live west of St. Louis (except Alaska, which is far enough north to catch part of the transit) you’ll have to wait until April of 2012 for your next opportunity.

Thanks to the Web, no matter where you live, you can watch the entire transit live. The European Southern Observatory based in Chile will have it live on their website. Viewing a virtual image of the transit means no concerns about solar filters to portect the eyes. Go there now and book mark the page.

I plan to be up 1:13 a.m. in Boston to log on and watch the first contact as well as what is called second contact at 1:32:55 a.m. Boston time (5:32:55 a.m. Greenich or Universal time) when the complete orb of Venus slips completely inside the Sun's circumference.

A word of caution -and I'm speculating here - but it will be interesting to see if the observatory's servers will be up to the traffic and have the bandwidth to meet the demands that I am sure will be made upon it.

Solar filters

We’ve written many times about not looking directly at the sun. Adults and most teenagers know this. The concern is with younger children who are hearing about a transit or an eclipse for the first time and don't realize the potentially harmful effects that may occur by looking directly into the sun with the naked eye.

So, to repeat: Watch young children. Be very carefull. Looking at the sun without a proper solar filter is the equivalent of putting your eyeballs in a microwave oven and turning it on high. Enough said.

Obviously, the safest way to watch the transit is to go to the website mentioned above. But the thrill of actually seeing a planet move in front of a star, not virtually but literally, warrants the effort. Many high school and university science classes will have safe viewing sites. Check them out on the web or in your local newspaper. If you have an astronomy enthusiast as a friend he or she will likely be setting up a telescope – with a certified filter. Ask to grab a peek.

One of the most widely available filters for safe solar viewing is shade number 14 welder's glass, which can be obtained from welding supply outlets. Another inexpensive alternative is aluminized mylar that is manufactured specifically for solar observation.

Unlike the welding glass, mylar can be cut to fit any viewing device. If you are thinking of buying or making a filter for observing the transit of Venus be sure to closely read the following two excellent articles from Sky & Telescope magazine: "Solar Filter Safety;" and
"Solar filter suppliers."

See related articles: Captain Cook, the transit of Venus, and a little trip to Tahiti; Here comes the Sun - and Venus; Check out Venus at its brightest