July 29, 2014

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A Transit of Venus: Who Cares?

The 3rd in a series of Astronomical Events is occuring in early June. So, why do we care?

It's a fair question.

Why should we care if there's a lunar eclipse, a solar eclipse or a transit of Venus?

Well, let's go back in time and think about this a little.

Most of us know there are nine planets in our solar system, and that Earth is the third planet from the sun. We were taught this in school.

But there was a time when we didn't know how large the solar system was, or that there were any more than five visible planets.

Our knowledge was limited to what we could observe and deduce from what we saw in the skies.

You may recall that astronomers were "wise men" in biblical times, educated men who studied the motions of the stars to predict seasons, significant events.

The lunar eclipse was one of the first visible proofs that Earth was a curved sphere. Hard to argue that when you see our curved shadow creep across the face of the moon.

The solar eclipse, while more startling, also taught us about the sun's composition.

And the transit of Venus--  a solar eclipse with Venus barely visible against the face of the sun-- happens twice every 125 years or so.  Which means this is the last one in your lifetime!

Kind of hard to gather data when it happens so rarely. You need to publish your findings for the next generation or two to take advantage of it.

The value of the transit of Venus is that we can measure how long and exactly what time the small dot of Venus passes from one edge of the sun to the other.

No, the skies won't darken, and the average Joe won't care about it.  However, the difference in time that this is observed not only helps us determine how wide the earth is, but also how far away these objects are.

Parallax can be used to determine distance, and in fact, this was the first crude observation that allowed us to suggest just how big the solar system was.

The first observation suggested the second planet was 2/3rd  as far from the sun as we now know it is.

Why is this important?

Because it shows man's increasing knowledge of the natural world...how far we've come, from just observing the heavens to measuring them.  And by measuring them, we know our place in the universe.

At one time, Man assumed we were the center of the universe, and those who suggested the Sun was the center of the solar system where shunned and made to recant under pressure from the authorities.

Nowadays, by common sense and logic, we can reason out the correct order of the solar system, based upon careful observation and logical reasoning.

And that's a good lesson for our children and all of us, no matter how remote or rare the celestial event is.

If you REALLY want to learn more about the Transit of Venus, and I hope you do, you can google search it, read on wikipedia, or study the voyages of Captain Cook, and Charles Darwin to learn more of how difficult this was to accomplish several hundred years ago, and why we should care today.

Don't miss it.

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