Wednesday, June 06, 2012

The Tranist of Venus seen from Flagstaff Arizona June 5, 2012

Regular readers of this blog will recall that we sought out an isolated (but named) point on Grand Canyon's South Rim for the recent annular eclipse. Since the park became so overwhelmed with eclipse watchers, I wanted to experience in as natural a setting as possible. So when an even rarer event known as the transit of Venus occurred on June 5, we wondered deeply where we would go to view it. I very much like non-social settings for events such as these, but I also don't necessarily feel attached to any one particular kind of location. I try to let the moment speak for itself in these kind of situations.

I first targeted the summit of Mt. Elden which sits high above above Flagstaff at the elevation of 9,299 feet. There is a road to its summit and it would have provided a clear and unobstructed western view. However, the windy conditions of the day really precluded that. So when the US Naval Observatory in Flagstaff announced that they would hosting a "transit party" I thought, "Why not." So, I loaded up my camera, filters and tripod and headed west on old Route 66.

The US Naval Observatory, Flagstaff Station (USNOFS) is located on top of a relatively young cinder cone about 4 miles west of Flagstaff. The observatory is set among a well-managed (i.e. thinned) Ponderosa pine forest.

The view from the top of the cinder cone and the observatory is spectacular! Looking to the north you can see San Francisco Mountain, a collapsed and eroded strato volcano that last erupted about 440,000 years ago. As you can see, northern Arizona was blessed with fantastic viewing conditions for the transit (and explains why the Navy chose this site for the USNOFS. I heard from friends in Florida and Massachusetts who were denied viewing because of overcast and my heart goes out to them for not seeing the transit as we did.

Here is a view of the sun at 3:00 PM MST as I approached the observatory. Note that Venus is not yet visible as 1st contact (when the planet first touches the outside disk of the sun) did not occur until 3:04 PM MST. I used my Canon Mark II 5D camera on a tripod with a 300 mm Image Stabilizer lens and 6400 ISO. A solar viewing filter was placed in front of the lens to allow shooting into the brilliance of the sun.

The view at 3:35 PM MST after Venus passes 2nd contact - when the entire disk of the planet is inside the disk of the sun. You can see Venus as the small black dot in the upper right of the sun. This will be about as spectacular as it gets since 300 mm lens is about as small as can be used to see something like this.

Attendees using the various instruments that were set up on the lawn outside the USNOFS

This photo was taken more than one hour later (at 4:40 PM MST) and clearly shows the planet making its way across the disk of the sun

There are numerous methods employed to safely view the sun and here is a reflective technique. The dark disk of Venus can easily be seen against the whitish appearing sun from this telescope. Note the faint splotches to the left of Venus - these are large sun spots that can bee seen when viewed this way.

View of the transit of Venus at 5:15 PM MST from the US Naval Observatory - Flagstaff Station

One of the highlights of watching the transit from the USNOFS was seeing it through the Clark 5-inch refractor telescope, made expressly for the USNO for the 1874 and 1882 transits. In 1874, this very telescope was used in Peking, China to observe the transit, while in 1882 it was sent to Wellington, South Africa. Eight of these were ordered for use in those two transits and six of them are still owned by the USNO, with this one permanently housed at the Flagstaff Station.

An astronomer recalibrating the viewing of the 5-inch Clark refractor

The engraving on the tube reads: "A. E. Clark & Sons, Cambridgeport, Mass." There was a long line for folks to view the transit through this telescope, even though video monitors showed it larger elsewhere on the grounds. A sense of history and rarity permeated the event.

Finally, at 6:25 PM MST, the transit reached its zenith, meaning that it completed half of its distance across the suns disk. Compare this to the first photos and you can see that Venus appears to travel from the top of the suns disk to its lower right. The entire transit lasted for 6 hours and 40 minutes and I saw 3 hours and 30 minutes of it.

A viewer watches the transit through a pair of strong binoculars with a filter attached. This was perhaps the best view seen of all the methods available.

My tripod setup for my camera. When the transit began at 3:04, the lens was pointed almost overhead but by the end of the day it was much more horizontal.

My final shot of the transit taken at 6:30 PM MST. The sunset yesterday in Flagstaff was at 7:38 MST meaning that there was still more than one hour left to view the transit before it dropped below the horizon. Look for Venus soon as the morning star in the eastern sky, as it continues in its orbit around the sun.

A big thank to the staff and volunteers at the US Naval Observatory - Flagstaff Station for opening up their facility and providing a world-class event that will not be seen on planet earth until 2117. Will blogs like this be as obsolete as the sailing vessels that took earlier astronomers to the 1874 and 1882 transits of Venus? Likely, it will but let's hope that this tiny narrative will be read by some future reader who might wonder about the June 5, 2012 transit of Venus!


  1. An absolutely stellar post! Fantastic in every way.

  2. Nice shots. I did pretty good with my 200mm and some cropping but only watched until 6:30 as the wind was just too much.


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