Zeev's Turnips Patch-No Politics (ZEEV)

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Zeev, you need a Venus transit

With all of the interest about the Venus transit in the coming weeks on ATS, I felt it would be best to provide ATS with a sort of guide to the event. This is an incredible rare event. So rare that in the time between 2000 BC and 4000 AD only 81 Venus transits shall occur.

A little information about Venus
Diameter: 7,520 miles, which is slightly smaller than the size of the Earth.
Distance: 67-million miles from the Sun (about .72 AU); 26-million miles from the Earth.
Rotation: 243 Earth-days long, retrograde (the Sun rises in the west). Its day is longer than its year.
Orbit: 221 Earth-days long.
Notable Features: Third brightest object in the night sky; known as the Evening or Morning Star; too often mistaken for a UFO; atmosphere mostly made of CO2, with sulfuric acid rain, temperatures exceeding 900 F, and lightening; no magnetic field or moon; no plate tectonics, volcanoes are caused by convection. Like the moon, Venus also goes through phases, but are only observable through a telescope.
History: Named after the Roman goddess of love, the Greek equivalent of Aphrodite. The day 'Friday' comes from Venus' name from the Saxons: Fria. To the Mayan's people Venus was the God of War, who beamed down rays of evil bringing about death and destruction. Because of these Mayan beliefs, their calendar is based off of the cycles of Venus, and ends in 2012 - shortly after the next time Venus transits the Sun.
Transit: The transits follow a cycle, taking 243 years. The last transit of Venus was 122 years ago, in 1882. The cycle is unique in the fact that two transits may be seen within a span of 8 years, but after the second transit one will not be seen for over a century. Transits do not occur every time Venus orbits for the same reasons solar and lunar eclipses do not occur all the time. The Earth and Venus do not orbit in exactly the same plane, so the Sun, Venus, and Earth must all be aligned perfectly. During the 19th Century astronomers used the transits of Venus to discern the size of the solar system and measure distances to nearby stars. Only 6 transits have been recorded by astronomers, beginning with the transit of 1631.

Where and when the transit will be visible
If you live in Europe, the Middle East, all of western Asia and most of eastern Asia, and most of eastern Africa, consider yourself lucky. All of the eclipse will be visible there. In the farthest eastern most parts of mainland Asia to Japan, Indonesia, and Australia the transit will begin at or during sunset. While if you live in eastern North or South America the transit will be in progress at sunrise.




























[line feeds for ATSNN]

NASA has listed times of contacts for major cities around the globe here: http://sunearth.gsfc.nasa.gov/eclipse/transit/venus/city04-1.html . For cities in the United States times are listed here: http://sunearth.gsfc.nasa.gov/eclipse/transit/venus/city04-2.html .

To read these graphs may seem a little tricky, but they are incredible easy to learn to read. First off, the times are given in UTC. I'll give an example using London, England.

quote:
Location External Sun Internal Sun Greatest Sun Internal Sun External Sun
Ingress Alt Ingress Alt Transit Alt Egress Alt Egress Alt
h m s ° h m s ° h m s ° h m s ° h m s °
London 05:19:54 12 05:39:47 15 08:22:42 40 11:04:05 59 11:23:36 61


Going from left to right: 'External Sun Ingress' is when Venus begins to touch the limb (edge) of the Sun on the way towards transit. 'Internal Sun Ingress' is the time when Venus has fully passed in front of the Sun. 'Greatest Sun Transit' is fairly obvious - it is when Venus has reached its peak in transit and is headed off of the disk of the Sun. 'Internal Sun Egress' is when Venus has reached the limb of the Sun and is starting to pass off of the disk of the Sun. 'External Sun Egress' is when Venus has fully passed off of the disk of the Sun.

The altitudes for each time are given in degrees above the horizon. To approximate these degrees, hold out your arm straight out and make a fist with your thumb on top of your hand (so your hand is on its side). That is about 10 degrees.

How to view the transit safely
DO NOT LOOK DIRECTLY AT THE SUN WITH AN UNFILTERED TELESCOPE OR WITH THE NAKED EYE!

That cannot be stressed enough. In doing so you could permanently damage your eyes or even cause blindness. Have you ever take a magnifying glass and burned leaves (and by leaves I mean insects)? Well that is what looking at the Sun is doing to your eyes.

"Projection"
One safe way, using any pair of binoculars or telescope, is to aim the device at the sun and allowing the magnified image to be projected out and onto a wall, sidewalk, or anything else white. An elaboration of this technique is to project the image onto a mirror angled towards a white wall or ceiling. This can allow for a larger image. Also, not only will you see Venus, but you may also see sunspots (if there are any.) Keep in mind: If you're using a telescope, keep the finder scope capped. If you're using binoculars, keep one of the tubes capped. This is because the two images would interfere with each other.

Pinhole Projector
This one is a mix of Astronomy and Arts and crafts. Using a large box (or a couple smaller boxes), some aluminum foil, a pin, and a sheet of paper you can view the sun. They're very simple to build, and a good activity for kids. The only downside is that the image is often unclear and unsatisfyingly small. For instructions on how to build one of your own: http://www.exploratorium.edu/eclipse/how.html

Exposed and Developed Black-and-White Film
Another mix of Astronomy and Arts and Crafts, though something the kids may not have as much fun with this time. First off, only true black-and-white film can be used. When developed a thin layer of silver, which is what protects your eyes, is formed. First, open a roll of black and white film, exposing it to sunlight for a minute or two. Have this film developed in order to get negatives to be used as the filter. Tape together two negatives, in order for best viewing and safety. If you want to really be a dork you can do as I did and buy some paper 3D-glasses, knock out the blue and red filters, and tape these film filters in their place.