Star Points for June, 2004; by Curtis Roelle
Planet Venus to Transit Sun This Week
On Tuesday morning there will occur a very rare transit of the planet Venus which you can see for yourself if properly equipped. Every person who has ever seen a Venutian transit has not survived to tell the tale. That is because the last one happened 122 years ago in 1882. That was also the year Jesse James was shot in the back and killed by Robert Ford.
In fact, only six transits of Venus have occurred since the telescope was invented in the early 1600's so some astronomers have been pretty excited about it. I say "some" because a transit of Venus has no real scientific value in 2004.
In the past transits of Venus provided rare opportunities for professional astronomers to do things such as determining the distance from the earth to the sun or detecting and measuring the Venutian atmosphere. These days distances within the solar system are so well understood that we've successfully dispatched spacecraft to observe Venus up close and personal.
The rarity of this event is its attraction. Although it is significantly more rare a transit of Venus doesn't come close to being the awesome spectacle of a total solar eclipse. However, we can view it without traveling to Antarctica as some astronomers did for last November's total eclipse.
Unfortunately, we are not poised for the best view of the transit. That is for the Europe and Africa. They will get to see the entire six hour and 12 minute event.
For viewers in Carroll County the transit will be more than half over by the time the sun rises at 05:40 EDT on Tuesday, June 8. Venus will be near the edge of the sun as it slowly drifts across its face. Venus will reach the edge of the sun's disc at 07:06 a.m. EDT and will take almost 20 minutes to completely egress. The transit ends at 07:25 a.m.
You can safely view it yourself but you must be extremely careful when observing the sun. You must consciously think about safely.
The Solar Theater
The safest way to view it is to project the sun's image. An easy device that is often used for viewing partial solar eclipses is an "eclipse theater" made from an old shoe box.
See the illustration with this article for construction details. Don't forget to throw away the lid before you try using it.
Here are a few steps for viewing with the theater:
This tiny dot is the planet Venus.
Magnified & Projected Image
You can create a larger and much easier to see image of the sun by projecting it with binoculars or a telescope. Projection doesn't mean looking through the binoculars. It means pointing the binoculars at the sun and projecting the image onto a white card or a piece of paper acting as a screen.
First make a sunshade by tracing around the objective (large) end of the binoculars on a piece of stiff cardboard. Cut out and discard the traced disc and slip the cardboard shade over the end of the binocular tube. You don't need the other binocular tube so keep it capped.
If equipped, mount on a tripod. Otherwise, hold them in one hand. Hold a white card or paper screen with your other hand and manipulate the objects in each hand until the projected solar image falls onto the screen. Focus if necessary. Changing the spacing between your hands alters the size and brightness of the projected image.
If you are observing during the transit you shall see the perfectly round black disc of the planet Venus in front of the sun. It will be only about 1/33rd of a solar diameter across according to Woodbine resident Ray Sterner of The Johns Hopkins University Applied Physics Laboratory (JHU-APL). You may also notice irregularly shaped sunspots in the magnified image. This method can be used on any clear day to see sunspots.
You can also view the transit directly with the unaided but filtered eye. Visit a welding supply store and ask for a #13 or #14 welding glass. Do not use lighter shades than these. The higher the number the darker the shade.
To the naked eye the sun appears to be about the same size as a pea at arm's length. Now, trying looking for a tiny black dot on the pea - Venus. It's possible, but you will probably be better off projecting the image onto a screen with binoculars or a telescope.
If you miss this one because of clouds or technical problems, don't worry. The next transit of Venus visible from Maryland will be on June 6, 2012.
If you miss the 2004 or 2012 transit you will be out of luck. The next transit after these will be in 2117.