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06/06/2012

The 2012 Transit of Venus Accross the Sun's Disk Witnessed by Hundreds at Rice

Tuesday evening, June 5, 2012, from a little after 5pm until sundown, visitors to the Rice University campus had on opportunity to see Venus transit across the face of the Sun. This is an extremely rare event that will not occur again until 2117, so for many of the people viewing this extraordinary event, it really was a once in a lifetime opportunity. Before the transit itself began, Dr. Patrick Hartigan of the Physics and Astronomy Department gave a public lecture describing why these transits occur as they do.  Dr. Hartigan's talk presented some historical context for the event and briefly described some of the celestial mechanics that governs the process. Typically, these events happen in pairs separated by 8 years (the previous Venus transit was in 2004), but the 8 year pairs are separated by a little over 100 years.  Transits of Venus occurred in the years 1761 and 1769, and these transits were obserevd by astronomers widely separated over the Earth.  The observations from the widely separated locations gave slightly different views of Venus crossing the Sun's surface, which allowed astronomers to calculate the true size of the solar system.  The results from these transit observations gave a distance from the Sun to the Earth that was only slightly off from the present day accepted value of 93 million miles.  The 2012 transit of Venus was observed by NASA's Hubble Space Telescope by observing sunlight reflected off the surface of the Moon.  As Venus passed in front of the Sun and blocked a small portion of the Sun's disk, the light reflected off the Moon dimmed ever so slightly.  Analyzing these observations will help astronomers better understand observations of other stars that host extra-solar planets which transit in front of their host stars, causing them too to dim just a little bit.

 

Following the talk, visitors to the campus were able to observe Venus transit at the Rice University Campus Observatory on the roof of the Brockman Hall for Physics, and with a number of smaller telescopes that were set up at various locations around the campus including outside the physics building as well as by the Barbara and David Gibbs Recreation and Wellness Center.  The public viewing lasted from 4:45 pm until sundown, at which time Venus was only about halfway through its journey across the face of the Sun.

 
 
RUCO    Sun_Venus


Left: The Rice University Campus Observatory (RUCO) sits on the fourth floor of the Brockman Hall for Physics.  Hundreds of visitors to campus witnessed Venus transit the Sun using a specialized solar telescope at the observatory.  

Right: An image of the Sun taken with the NASA Solar Dynamics Observatory satellite.  Venus is the black circle at the top left of the Sun.  This photo was taken shortly after Venus began to pass in front of the Sun.  Over the next ~6 hours, Venus travelled to the right and slightly down.  Also visible on the solar disk are several smaller, black sunspots: regions on the Sun's surface where strong magnetic fields stick out of our star, causing the gas contained within them to cool down to a modest 3000 degrees Kelvin compared to the rest of the Sun's surface which is at about 6000 degrees Kelvin.