Get ready for a sight you’ll never see again…

I love nuggets of knowledge and tidbits of trivia, which probably explains why I like the Reader’s Digest so much. First of all there are usually a few “funnies” that make me smile, such as the one I just read in the May 2012 issue: “I love being married. When I was single I got so sick of finishing my own sentences.” Comedian Brian Kiley

There was another good one in a previous issue, but I can’t recall who said it. That one went something like “I was one of seven children. I didn’t know what it was like to sleep on my own until I got married.” (grin)

But that’s not what I wanted to talk about. One interesting snippet in this month’s issue was a reminder that the next Transit of Venus will occur on June 5 or 6, 2012, depending on your location. Observers in North America see it on the evening of June 5. This is something we don’t want to miss, because it will be the last transit of Venus to occur in our lifetimes.

As an aside, there’s even a Transit of Venus Phone App (both iPhone and Android) that will allow you to send your observations of the 2012 transit of Venus to a global experiment to measure the size of the solar system. You can find out more about this on TransitOfVenus.org

But what is a Transit of Venus? Well, when Venus passes directly between earth and the sun, we see the distant planet as a small dot gliding slowly across the face of the sun.  Historically, this rare alignment is how we measured the size of our solar system. The duration of such transits is usually measured in hours. A transit is similar to a solar eclipse by the Moon. However, although the diameter of Venus is almost four times that of the Moon, Venus appears smaller, and travels more slowly across the face of the Sun, because it is much farther away from Earth.

As another aside, I just read about an interesting Black Drop effect while rooting around the TransitOfVenus.org website, which says: "Just before or after the circular black dot of Venus seems to touch the edge of the sun, a peculiar 'black drop effect' sometimes occurs between the contact points.  A ligament of darkness smears the juncture of Venus and the sun as shown in this image." Well, I’m certainly going to be looking out for this!

Transits of Venus are among the rarest of predictable astronomical phenomena. They occur in a pattern that repeats every 243 years, with pairs of transits eight years apart separated by long gaps of 121.5 years and 105.5 years. A transit of Venus took place on 8 June 2004 and (as noted above) the next will be on 5 or 6 June 2012. The previous pair of transits were in December 1874 and December 1882. After 2012, the next pair of transits will be in December 2117 and December 2125, but (sad to relate) I think I will be otherwise engaged on both of those occasions.

Of course, we all know that staring at the brilliant disk of the Sun (the photosphere) with the unprotected eye can quickly cause serious and often permanent eye damage. Fortunately, the forthcoming transit of Venus can be safely observed by taking the same precautions used when observing the partial phases of a solar eclipse. One cheap-and-cheerful solution is to don special Solar Eclipse Shades as shown below:


You can get this type of thing all over the place, but you do want to make sure they are “legit” and will do the job. The cheapest I’ve found so far is from Woodland Hills Telescopes at $0.95 each, falling to $0.85 for 25 pairs, with bigger price breaks the more you buy. (I just ordered 25 pairs so that (a) I can share them with my family and friends and (b) I won’t have to give up my own pair [grin].)

As it says on the Woodland Hills website: "The lenses used in these Eclipse Shades are made of scratch resistant, optical density 5, 'Black Polymer' material. These shades filter out 100% of harmful ultra-violet, 100% of harmful infrared, and 99.999% of intense visible light. These premium filters also create a sharper ORANGE colored image of the sun."

Also of interest is the fact that all proceeds from the sale of these glasses are going to support programs by Astronomers Without Borders, whose mission is to: “Fosters understanding and goodwill across national and cultural boundaries by creating relationships through the universal appeal of astronomy.”

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