Southern California -- this just in

« Previous Post | L.A. NOW Home | Next Post »

Transit of Venus: Feeling solar withdrawal? Watch Venus cross sun

May 21, 2012 |  6:40 am

This post has been corrected, as indicated below.

Feeling down after the end of the eclipse? Another rare astronomical treat will happen in just a few weeks: Venus will block the sun in June. And it's a good opportunity to watch — the next chance on Earth won't come for 105 years.

It's the same idea as a solar eclipse — Venus moves in a way that blocks light from the sun to Earth. But because Venus is so much farther away than the moon, observers will see only a tiny black dot move across the surface of the sun.

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. And the most recent time Los Angeles has seen a Transit of Venus was in 1882, the Griffith Observatory said.


According to a video posted on transitofvenus.org, 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 disc 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.

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 June 6.

Transit-of-venusThe continental United States and southern Canada will get a partial show in the afternoon of June 5, 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 the website Eclipser written by 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 June 6.

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. More discussion on global climate for the transit can be found here.

Here are some tips on how to watch the show:

On June 5, the transit begins just after 3 p.m. Pacific Daylight Time and ends just before 10 p.m. (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 at the sun! Viewing the sun can literally cook the eye's cells and cause blindness. According to NASA, children and young adults are most likely to suffer from eclipse blindness.

Here are some suggestions on how to view the Transit of Venus safely:

1. Buy a pair of $2.99 eclipse glasses or a $9.99 "Solarama" device that projects an image of the sun to a piece of paper. The city-run Griffith Observatory in Los Angeles is supposed to have them on stock but ran out of eclipse glasses before Sunday's eclipse and was short on Solaramas. 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, according to the Exploratorium, because they don't have enough resolution to show the planet's shadow.

3. But you could try using a pair of binoculars, preferably with more than 7 times magnification, 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. See the Exploratorium website for more details.

4. One of the best ways is to let the experts help — and watch it magnified. Go to the Griffith Observatory or any place similar that is equipped with solar filters over telescopes. The Griffith Observatory will make available, for free, access to telescopes with appropriate filters.

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

[For the Record, 4:29 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. ]


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