Transit of Venus

June 5, 2012, 2:45 pm - 9:30 pm 
The transit of Venus produced a spectacular show (see CBC report). Another transit of Venus will not occur in your lifetime (unless you plan to live to 2117!). 
Phil, Dan, and Milan capture the transit while in
Victoria, BC (see top image of transit).
Photo credits: Phil Morris
Transit Benchmarks
  • 3:05 pm – Ingress (Venus began crossing the Sun)
  • 6:27 pm – Venus was half-way through the transit
  • 8:00 pm-ish – we lost the view of the Sun as it disappeared behind the houses and trees – we watched the rest of the event through a live video feed from Hawaii
  • 9:15 pm – sunset
  • 9:30 pm – Egress began 
  • 9:48 pm – Venus finished crossing the face of the Sun
         Read more . . .  
         Tips for safe solar viewing
What is the Transit of Venus?
The transit of Venus is a very rare astronomical event (a pair of Transits occurs every 243 years). It occurs when Venus comes between Earth and the Sun. It occurs rarely because Venus’ orbit is inclined with respect to Earth’s and usually appears to pass over or under the Sun. During a transit, Venus can be seen moving across the face of the Sun. 
                         Measuring Venus transit times to determine solar parallax
                         Credit: Vermeer, Duckysmokton, Ilia
Historically the transit of Venus was an important event. Edmund Halley (as in Halley’s comet) suggested that the transit could be used to find the answer to a very important question – the distance between the Earth and the Sun. This information could then be used to calculate the size of the solar system.
For the 1761 and 1769 Transits, astronomers were sent all over the world to view and time the transits. In 1769, Captain James Cook made observations from Tahiti. Their calculation was refined during the 1874/1882 transits. The transit of 1882 created a lot of public interest, including the creation of an original piece of music by John Phillips Sousa (wikimedia audio file).

Tips for safe solar viewing
Cam and Raminder discuss the
Sun and safe solar viewing.
A solar eclipse or a planetary transit is a rare and striking phenomenon you won't want to miss but it is vital that you protect your eyes at all times with the proper solar filters.
Viewing with Protection -- Experts suggests using a number 14 welder's glass. The welding hood must have a #14 or darker filter. Do not view through any welding glass if you do not know or cannot discern its shade number. Be advised that arc welders typically use glass with a shade much less than the necessary #14. A welding glass that permits you to see the landscape is not safe.  Best to use inexpensive Eclipse Shades which have special safety filters that appear similar to sunglasses, but these filters permits safe viewing. We will be handing out Eclipse shades during our event.

Telescopes with Solar Filters -- The transit of Venus is best viewed directly when magnified, which demands a telescope with a solar filter. A filtered, magnified view will clearly show the planet Venus and sunspots.  Never look through a telescope without a solar filter on the large end of the scope. And never use small solar filters that attach to the eyepiece (as found in some older, cheaper telescopes.)

Pinhole projectors -- These are a safe, indirect viewing technique for observing an image of the Sun. While popular for viewing solar eclipses, pinhole projectors will not offer as much detail during a transit, small features like the halo around Venus will not likely be discernible.  That said, they are still the easiest way to witness the event with minimal cost or fuss. 

Related projection methods -- One viewing technique is to project an image of the Sun onto a white surface with a projecting telescope, sometimes called a solar funnel.

No matter what recommended technique you use, do not stare continuously at the Sun. Take breaks and give your eyes a rest! Do not use sunglasses: they don't offer your eyes sufficient protection.
For more information about safe solar viewing, visit  NASA Eye Safety During Solar Eclipses

Other links about the Transit
Curious to learn more about the Transit of Venus? Follow these links:

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