Posted on 11/06/2006 2:35:41 PM PST by paulat
Mercury crossing the sun Wednesday By SETH BORENSTEIN,
AP Science Writer 55 minutes ago
An infrequent astronomical sight — tiny Mercury inching across the surface of the sun — takes place Wednesday afternoon in North America. But you'll need the right kind of telescope to see it.
Mercury is so tiny — 1/194th the size of the sun — and looking at the sun is so dangerous to the eyes that viewing must be done with a properly outfitted telescope or online telescope cameras, experts say.
Still, for many people, it may be the only chance to see the closest planet to the sun, said Michelle Nichols, a master educator at the Adler Planetarium in Chicago, one of many places that will hold special viewings of Mercury's trek. Mercury is usually seen in the early evening, but it's often obscured by buildings, city lights and trees, she said.
"You definitely need a telescope to spot this one, a properly filtered telescope," Nichols said. "You will see a small black dot against the face of a bright sun."
Several Web sites, including those from mountain peaks in Hawaii, will be showing Mercury's trek online.
Mercury will travel between the sun and Earth in a way that makes it appear to cross — in astronomy the word is "transit" — the bottom third of the sun from left to right.
Mercury's five-hour trek starts at 2:12 p.m. EST. People in Western time zones of the United States should be able to see the entire trip.
The last "transit of Mercury," as it's called, was in 2003. These events occur about 13 times a century, with the next one happening in 2016, according to NASA.
That's more frequent than the transit of Venus, which happens in pairs, roughly twice in each century. (The next one is 2012).
Because of the timing of this year's transit of Mercury, it will be visible in North and South America, Australia and Asia, but not in Europe, Africa, the Middle East and India, where it will be nighttime.
___
On the Net:
Time zone listings for Mercury transit:
http://sunearth.gsfc.nasa.gov/eclipse/OH/LC/Tran06LC2.html
The path Mercury will take across the sun:
http://sunearth.gsfc.nasa.gov/eclipse/OH/tran/TM2006sun.GIF
NASA on the transit:
http://sunearth.gsfc.nasa.gov/eclipse/OH/transit06.html
Transit of Mercury from a Hawaiian summit:
http://astroday.net/Merctransit06.html
Ping-a-ding-ding!
Wouldn't SOHO also provide a good view?
A lot of people have seen Venus, but few have seen Mercury and probably fewer all the time. You have to be in the right place at the right time and it is a fairly short time. It's bright, almost as bright as Venus, but it sets right after the sun so there is just that short piece of time after sunset when Mercury becomes visible and when it hits the horizon. Vice versa for sunrise.
There's another way you might be able to see it; it's the way I viewed a solar eclipse. Take a cardboard box big enough to put your head in without blocking the side; think the size big enough to put a TV in. Cut a 2" square in one end and tape a piece of aluminum foil over it. Put a very small hole in that foil; try a pin or a finishing nail. Inside the box, tape a piece of white paper. Stick your head in the box such that your head does not block the light path. Orient the axis that runs though the center of the paper and though the hole in the foil towards the sun. An image of the sun will project on the paper, and you may be able to see the image of Mercury (and any sunspots!) on it.
My way is similar in that it uses pinhole technology, but there's no box and the image is quite large. Just take a small mirror (shape doesn't matter) and place it in a window so that it catches the sun's rays and projects them across the house to a white wall or piece of paper hung on a wall. If the distance is far enough the image will be sharp and you will be able to see Mercury. If the distance is not far enough that the image is still blurred, then mask out part of the mirror until you still have a visible image. Darken the room if necessary.
Essentially, you are making your house into the box and the mirror represents the pinhole. The image will move as the earth rotates, and you may need to reposition the mirror, but it works!
Unfortunately, with mercury only 0.5% the sun diameter, what works to display a crescent in a partial solar eclipse will probably not show evidence of Mercury's transit.
Sic transit gloria Mercury?
I wonder. I bet there will be special telescopes with filters near me. I wonder how long it will last. I better get to the front of the line
Can it be viewed online anywhere?
It moves fast. If someone can project the image on a screen then a crowd can all view it at once with good safety to the eyes.
ping
Excellent! I JUST happened to get a new solar filter for my scope just last week and haven't gotten around to checking it out yet. Looks like this'll be a good time to.
Thanks for posting
Your method probably won't work in this situation, Ron. Bear with me as we do the math:
If the distance from the pinhole to the end of the viewing box that serves as the viewing screen is, say, 48 inches, then the projected solar image will have an approximate diameter of 48 times tan (angular extend of the Sun) or 48 times tan 0d 30m = 0.42 inches.
Now recall from the article that Mercury's apparent diameter is only 1/192 that of the Sun. Dividing, 0.42 / 192 = 0.002 inches would be size of the dot of the projected Mercury.
Because atmospheric turbulence and small imperfections in the pinhole will cause deterioration of the contrast, so small a dot probably would not be easily found on the "viewing screen."
It'll transit just below sunspot 921... should be a nice view!
Pop-Tart mylar over a camcorder lens is even better. That way you don't have to look at the sun at all -- you just point the camcorder at the sun and look at the screen.
Whatever works best for you. I have a visual solar filter for my telescope, but it is too dense for photographic use. So I will attempt to project the Sun's image through the telescope onto a white surface, hoping to see AND photograph Mercury -- weather permitting, of course. The weather forecast for my area isn't looking good.
ping
Most of us don't have telescopes and have to "make do."
I have a marine sextant with all kinds of filters.
We're having hurricane winds and 100 year flooding & rain & darkness in the middle of the day.
Not likely to need the filters.
Disclaimer: Opinions posted on Free Republic are those of the individual posters and do not necessarily represent the opinion of Free Republic or its management. All materials posted herein are protected by copyright law and the exemption for fair use of copyrighted works.