Physics Photo of the Week

September 7, 2012

Transit of Venus
On June 5, 2012, soon after the 2012 Commencement at Warren Wilson College, much of the world was able to view the last transit of Venus across the Sun until December 2117 - more than 105 years from now.

I photographed this event from the Craggy Visitors Center at an elevation of 5500 feet with the help of my wife Vicki, and WWC alumnus Gary Starkweather and his wife Vandy - both avid amateur astronomers.

Venus transits are extremely rare due to the orbital inclination of Venus' orbit (3.4 degrees relative to Earth's orbit) and the relative closeness of Venus to Earth that the angular separation between Venus and the Sun at the conjunction is often highly magnified.  Venus, about the size of the Earth, appears relatively large also because it is so much closer to Earth than the Sun.  If Earth and Venus were the same distance as the Sun, they each would appear significantly smaller than the sunspots visible on June 5 - about 1/100 the diameter of the Sun.  The June 5, 2012 event was only the seventh recorded Venus transit in over 400 years of telescope observations and only the 4th Venus transit that was photographically recorded.  However, with the rapid development and availability of digital cameras, the 2012 transit is estimated to have been photographed by over 20,000 amateur and professional astronomers throughout the world. 

The above image is only one of several hundred images taken with a 3 1/2 inch Questar telescope (donated to WWC by Ralph Brown of Chattanooga, TN) and a digital camera.  Some have been made into a time lapse video clip shown at right.  The frames for the sequence were recorded once a minute and played back at 33 times a second.  This playback speed is almost 2000 times the original speed. 

Also shown below is the final image just before sunset where Venus' silhouette can barely be seen between clouds near the horizon - about 1/3 across the Sun from the top.  The final image was taken with a "standard" zoom telephoto lens with no filter other than the extensive Earth's atmosphere at the horizon.  The other photo (by Gary Starkweather) shows several other amateur astronomers and onlookers at the Craggy Visitors Center.
 



Physics Photo of the Week
is published weekly during the academic year on Fridays by the Warren Wilson College Physics Department. These photos feature interesting phenomena in the world around us.  Students, faculty, and others are invited to submit digital (or film) photographs for publication and explanation. Atmospheric phenomena are especially welcome. Please send any photos to dcollins@warren-wilson.edu.

All photos and discussions are copyright by Donald Collins or by the person credited for the photo and/or discussion.  These photos and discussions may be used for private individual use or educational use.  Any commercial use without written permission of the photoprovider is forbidden.

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