What Is As Rare As a Venus Transit in June?


Were you caught up in the Venus Transit kerfuffle? I was and I wasn't. I was to the extent that I was keenly fascinated by what was happening and by its rarity. But I wasn't about to risk my sight to see something like a  photograph of a  retina with peripatetic blind spot.

I did what I usually do about big events. I read about it. In the June issue of "Astronomy" magazine.  Therein is a concise and clear description. "Little black spot---How to view June's rare Venus transit" by Richard Talcott.  With ample graphics too.  Here are a few transitory tidbits I learned.

1. This actually was the second Venus transit this century. It also occurred in 2004. That one lasted  6 hours and 13 minutes, slightly less than this year"s.

2. Venus transits are rare because Venus' orbit tilts 3.4 degrees to the plane of Earth's orbit.  A fact that accounts for Venus usually passing slightly above or below the Sun.

3. The transit was not visible to people in western Africa and eastern South America.  Brazil must have been celebrating other activities associated with Venus.

4. Welders had a better chance of seeing it. With a #14 welder's glass that blocks out dangerous ultra-violet and infrared radiation as well as visible light.

5. Hubble Space Telescope astronomers  viewed  the transit by observing sunlight reflected from the Moon.  For further clarification of what this means, please text the Adler Planetarium.

6. Viewers who used a Hydrogen-alpha solar filter actually could spot Venus before it crossed the limb (edge) of the Sun. The filter" showed the Sun's chromosphere---the layer of the Sun's atmosphere just above its visible photosphere---and  revealed Venus' black disk projected against it."

7. During the transit Venus covered 0.1 % of the Sun's area, reducing the amount of sunlight by the same proportion.

8. Astronomers used #7 fact to detect exoplanets, or planets orbiting other stars.

Let me end by quoting this superb article's peroration: "Observers will have to wait to December 10/11, 2127 to see another Venus transit. Who knows---by then the Cubs just might have won another World Series."

That thought crossed my mind too.

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