Rare Venus event puts it between Earth, sun

Enquirer ^ | 4/18/04 | Dean Regas

[LibWhacker]

The world was a very different place the last time a transit of Venus occurred on Dec. 6, 1882. This astronomical event is so rare, that no one alive has seen it.

A transit of Venus occurs when the planet comes directly between the Earth and the sun. Venus is then visible as a small beauty mark on the face of the sun.

The 1882 transit was visible throughout most of the Western Hemisphere. Viewing this transit took on extra urgency for astronomers and the general public because the next transit would not occur until this year.

So a long wait is over. On June 8, Venus will once again transit the sun and the eastern half of the United States can witness it.

Transits of Venus crop up in pairs eight years apart, but more than a century separates any two pairs. The transit this June will be followed by another in 2012 (which will be visible in the western half of the United States). But don't wait for 2012 - it could be cloudy on one or both of those days. And I'm sorry to say that you won't live to see the next pair in 2117 and 2125.

1631 and 1639

Johannes Kepler predicted the first transit of Venus in 1631. No one saw it. The Thirty Year's War, cloudy weather, and the short duration of the transit made observing impossible.

The next transit in 1639 was only viewed by two astronomers in England. Jeremiah Horrocks calculated the transit and employed his friend William Crabtree to observe from a neighboring city. The day of the transit started off cloudy. But late in the afternoon the clouds parted and Horrocks "beheld a most agreeable spectacle, the object of my sanguine wishes, a spot of unusual magnitude and of perfectly circular shape."

1761 and 1769

Not everyone was as lucky as Horrocks. European countries mounted great expeditions to the far corners of the globe to see the transits of the 18th century. If accurate measurements of the transit could be made at opposite ends of the Earth, astronomers could calculate the distance from the Earth to the Sun (and also the distance to each planet).

Astronomers traveled to Siberia, India, Madagascar, South Africa and the South Pacific. Some were welcomed with clear skies. Others missed the entire thing.

One of the greatest adventures to see the transit of 1769 was led by Captain James Cook, who took his crew to the island of Tahiti. From Point Venus, Cook and company had perfect weather and a nice stay in a tropical paradise.

1874 and 1882

After 105 years, astronomers eagerly awaited the transit of 1874. Russia, Britain, France, Germany, Italy, Holland, and America funded 62 expeditions to see it.

Astronomers used a new invention: the camera. The American teams alone captured 350 pictures of the 1874 transit and 1,700 images of the 1882 transit.

The transit of 1882 was especially viewable from the United States. And not just astronomers were geared up for the event. This was one of the most talked about cultural events of the year. This transit was continually reported in newspapers and sales for smoked glass (the "safer" method of observing the sun in 1882) skyrocketed. The New York Times reported: "This is the first time within the memory of man that the unlearned common people have been permitted to observe a transit."

Safety

Looking at the sun will damage your eyes, so the easiest and cheapest way to observe it safely is by looking through eclipse shades. For about $3, these glasses will allow you to observe the sun, transits, partial eclipses, and maybe even a large sunspot. Eclipse shades are available at the Cincinnati Observatory or from Rainbow Symphony at http://www.rainbowsymphony.com/eclipse/soleclipse.html

Don't wait for June 8 to see Venus. You can watch it blazing in the western sky after sunset, brighter than any other star-like object.

[LibWhacker]

Be real careful about viewing the sun or any planets that are transiting across its face. You can find articles on safe viewing of the sun over at Sky & Telescope or Astronomy Magazine, or you can use Google to find some other publication that knows what it's talking about; i.e., an astronomy magazine and NOT, e.g., the NY Times. Don't take any one person's advice, including mine. Rather do a little research and find out for yourself (your eyes are on the line)! Here's one such article. Note: so-called "sun filters" sold with cheapo telescopes are generally not sufficient.

[68skylark]

Good article. But I don't think I want to wager my eyesight on a $3 pair of eclipse shades.

[RightWhale]

Make a pinhole camera and view the projected image rather than looking through any kind of glass or lens directly at the sun.

[pageonetoo]

The absolute safest way to observe the sun, is through a pin hole in a blocking sheet (whatever you have), properly focused, and allowed to hit a white panel beneath it. The image is displayed with detail, and allows you to watch it continuously, with no fear of harm to your eyes!

We went to White Lake, NC, in 1973(?) for a solar eclipse, and we set up a couple of these things. They work.

Idiot me, decided that I could look at the thing directly, when it was in full coverage. I have a little round dead spot in my vision as a result. Oops!

I did a google search of pinlole viewers... this is one of the responses:

http://www.zetatalk.com/teams/tteam34n.htm

[Kirkwood]

The safest way to view this transit is still the time-tested method of screen projection where the image of the sun through a pinhole onto a sheet of white paper.

Slightly more elaborate is to use a telescope or binoculars to project an image. Benefit is more light. Disadvantage is possible heat buildup in the optics and danger of someone thinking they can look through the telescope safely in this mode. Also you have more trouble tracking the sun unless you have a motor drive mount.

Next come filter materials over naked eye. Disadvantage is that the image is very small and you are assuming that someone made the filter correctly. Hard to know for sure unless it is verified by the manufacturer. I really see no advantage with this for a simple transit event because of the small image size.

Next comes filtering over the telescope objective. Advantage is a large image with detail. Disadvantage is that you have to be absolutely certain that the filter is correct for your application and does not leak light or could come off accidentally at any time. It must go over the objective and never over the eyepiece.

Finally, all eyepiece sun filters sold to amateurs are very dangerous to use because they can easily break due to heat. The only safe eyepiece filters are the costly professional types of filters (e.g., h-alpha).

You can enjoy this event safely and I would suggest a projection method to do so.

[Kirkwood]

"Idiot me, decided that I could look at the thing directly, when it was in full coverage. I have a little round dead spot in my vision as a result. Oops! "

Not possible. If the sun was fully covered you would have no damage. Perhaps you looked before or after full coverage in order to glimpse the diamond ring effect. I have found that most damage occurs BEFORE the big day when people are trying out their equipment and filters and do something wrong.

[narby]

Looks like this will be mainly viewable in Europe. Bummer...

[LibWhacker]

Disadvantage is . . . the . . . danger of someone thinking they can look through the telescope safely in this mode.

I remember reading about an amateur astronomer who used to set up his projecting sun scope at fairs and the like so the public could see a nice large projected image of the sun.

He had the thing roped off so people wouldn't look directly through the eyepiece, but he still had to fight 'em off with a stick.

His standard line was, "Before you put your eyeball up to that eyepiece, why don't you try putting your hand up there first?" That always worked. 'Course, nowadays it'd probably get you sued.

[Charles Henrickson]

Venus envy.

[jaz.357]

So starting on June 8, the "VIRGO'S" rule the Zodiac!

We have waited since 1882 for this!

[Pagey]

bttt

[LibWhacker]

Another alternative is the SunSpotter.

Pros: Highly rated sun scope. You get a nice big projected image of the sun. So it's fairly safe.
Cons: Costs $335. Not idiot proof. Not child-proof. You'd have to supervise closely any idiots or children who happened to be using it.

[GATOR NAVY]

When I was on board a ship I used my sextants to look at the sun. But they're a little pricey just to buy one for that reason.

[LibWhacker]

Always loved those things, expecially the brass ones. They look like a work of art, sculpture, to me. Wouldn't have a clue how to use one though. Look great on the coffee table, lol!

Can't you get a nice working brass model for two or three hundred bucks?

[fidelis]

"The safest way to view this transit is still the time-tested method of screen projection where the image of the sun through a pinhole onto a sheet of white paper. "

This is the method we used last time we had a partial solar eclipse visible in Arizona. Projected against the wall in our yard, it was quite clear. My kids were thrilled, anyway. That's what counts.

[GATOR NAVY]

Here's some brass models about that price range. I notice there are no real specs given. I suspect they would be fun to goof around with but I wouldn't make one the primary instrument on my solo round the world sail.

Sextants

[jerod]

I l ked at t e un on e d ring an ecl pse a d I did t su er any ill e ects.

[Mannaggia l'America]

The-Venus-in-between-us.

[Wacka]

This won't work for this, but you can see the shape of the sun during a partial eclipse by looking at light filtering through trees.
The spaces in the leaves act like lenses. When the sun is a crescent, you see small crescents all over the pavement instead of circles!
I saw this during the last partial eclipse in CA.

[Renegade]

A welding helmet works fine with me .