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College of Arts & Sciences

The Transit of Venus — June 5, 2012


Transit of Venus Viewing Session

On June 5, 2012 the Physics Department hosted a special viewing session, organized by Physics faculty member Dr. Tom Foster, to observe the transit of Venus which occurred that afternoon.  The session was held at SIUE's Roy E. Lee Baseball Field, where solar filters were handed out for safe viewing of the sun and filtered telescopes were set up.  The event was well attended with several hundred people showing up to see this rare astronomical event which will not occur again until the year 2117.

Venus is the next planet (orbit-wise) in from the earth toward the sun; it is the object that was shining brightly in the western evening sky for several months beforehand and will be shinging brightly in the eastern pre-dawn sky for several months to come.  As Venus goes from an evening to a morning spectacle, it comes between the earth and the sun — but usually not exactly, because the orbits of Venus and the earth are not quite in the same plane.  Sometimes, however, Venus does comes exactly between the earth and the sun, and is then visible (with suitable eye protection) as a tiny black dot crossing the surface of the sun — a "transit of Venus".  This happens very rarely; in fact the 2012 transit is only the seventh one whose observation has been documented in recorded history.

In the 2012 transit it took 6 hours and 40 minutes for Venus to cross in front of the sun.  About half of this was visible from Edwardsville until the sun set.  Clouds partly obscured the beginning of the transit, but we were fortunate to have a clear view of the sun most of the time after that (see photo below).

In recent centuries, transits of Venus have been occurring in pairs with two transits 8 years apart.  The "companion" to the 2102 transit occurred on June 8, 2004; the last part of it was visible from Edwardsville for a short time after sunrise.  On that morning, a handful of dedicated observers met before dawn on the roof of Founders Hall to get a clear view of the transit when the sun came up.  The last two transits before that were in December of 1874 and 1882.  The next pair of transits will occur in December of 2117 and 2125.

Besides being an interesting and rare curiosity, observations of transits of Venus have been scientifically important in increasing the accuracy of measurements of distances in the solar system, gaining more information on Venus' atmosphere, and obtaining other astronomical information.

Below is a montage of photos taken by Physics Emeritus Faculty member Roger Hill during the viewing session, starting with Venus crossing the edge of the sun and ending near sunset when the transit was about halfway through.  The photos were taken with a Canon Digital Rebel XTi and a 400-mm telephoto lens (equivalent to a 640-mm lens on a 35-mm camera), with a filter cutting out 99.99% of the sun's light.  Note the sunspots visible in addition to Venus (not to mention the clouds).  Clicking this image (or this link) will give a higher-resolution image.

Transit of Venus - RCH


This page:  http://www.siue.edu/PHYSICS/VenusTransit.html
Written by:  Roger Hill (
rhill@siue.edu)
Viewing session photo by Roger Hill
Revised:  2012 Jun 24
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