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Transit of Venus: Excitement builds for astronomical rarity

June 1, 2012 |  1:15 pm

This post has been corrected and updated, as indicated below.

Excitement is already building for the transit of Venus, an astronomical event that won't occur again for 105 years.

Late Tuesday afternoon Pacific time, Venus will cross in front of the sun from the Earth's perspective, producing a small, visible dot that will glide from left to right across the top of the solar disk.

Transit-of-venus-graphicIt's a very rare event: The transit of Venus has only happened seven times since the telescope was invented, according to NASA's Fred Espenak.

The last time was in 2004, but the Western United States was unable to view it. The most recent time Los Angeles has seen a transit of Venus was in 1882, L.A.'s Griffith Observatory said.

According to an online video from Slooh Space Camera, astronomers used the transit of Venus to calculate the size of the solar system.

Knowing it was so rare, countries sent out ships around the world "to time, to the second, how long it took the disk of Venus to move from one edge of the sun to the other," the video said. It was from this data that scientists were able to calculate the distance of the Earth to the sun, according to the video.

PHOTO GALLERY: Solar eclipse

Those with the best seats for Venus' transit will be in eastern Australia, New Zealand and eastern Asia, weather permitting. For those west of the International Date Line, the eclipse occurs on Wednesday.

Transit-of-venusThe continental United States and southern Canada will get a partial show on Tuesday evening, but the sun will set before Venus finishes her journey. The same show will also be visible in Mexico, Central America and the northern edge of South America, according to astronomer Jay Anderson.

Meanwhile, most of Europe, eastern Africa, and the rest of Asia will see the tail end of Venus' transit after the sun rises on Wednesday.

In terms of climate and location, eastern Australia or Hawaii are prime spots to watch this transit. In the continental U.S., the Southwest is your best option.

California has better-than-even chances of clear weather on a typical June afternoon, and Arizona has a more than 90% chance of clear skies, Anderson wrote. Thunderstorms can be a problem elsewhere in the U.S.

The transit begins just after 3 p.m. Pacific time and ends just before 10. (Obviously, in Los Angeles, we won't be able to see the transit after the sun sets just past 8 p.m.)

And just like with the eclipse, don't look directly at the sun! Doing so can literally cook the eye's cells and cause "eclipse blindness."

How to view the transit of Venus safely:

1. Buy a pair of $2.99 eclipse glasses. The Griffith Observatory had a supply of eclipse glasses as of Friday night. A No. 14 welder's filter will also work. Safe filters block all but 0.003% of visible light. But given the recent eclipse craze, they may be extremely difficult to find.

2. Pinhole projectors used during the eclipse probably won't work this time, experts say, because they don't have enough resolution to show the planet's shadow.

3. You could try using a pair of binoculars, preferably with a magnification power above 7, to project the sun's light onto the sidewalk or a piece of paper. If you're able to find an image of the sun, look for a tiny dot showing the image of Venus.

4. One of the best ways is to let the experts help — and watch it magnified. Go to Griffith Observatory or any place similar that is equipped with solar filters over telescopes. Viewing will be free at the observatory.

5. If all else fails, watch a live webcast. Transitofvenus.org points out that NASA will be broadcasting live from Hawaii.

Able to photograph the transit? Tweet it to us at @LANow and tag it with #LAVenus. You can upload photos to our website.

[For the Record, 4:27 p.m. June 1: An earlier version of this post said that the Western Hemisphere was unable to view the transit of Venus in 2004. As this corrected version notes, that transit was not visible in the Western United States.]

[Updated, 8:51 p.m., June 1: The Griffith Observatory now has a supply of eclipse glasses for sale, as of Friday night.]


Solar eclipse 2012 through the eyes of readers

Solar eclipse: For all the hype, it was quite a show

Solar eclipse was real-life astronomy lesson for millions

— Rong-Gong Lin II

Graphic courtesy of Griffith Observatory. Photo: The planet Venus (a small dot at the bottom of the image) passes in front of the sun in 2004 in this photo taken through the National Planetarium telescope in Kuala Lumpur, Malaysia. The last time it occurred was in 1882. The next crossing will be in June 2012, but the one after that will be in 2117. Credit: Ahmad Yusni / EPA