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2012 Transit of Venus
Tuesday, June 5th: 4:00 - 8:00 pm MDT
DU's Historic Chamberlin Observatory & DMNS
Venus Transit - Joe Gafford 
Venus Transit
2012 Joe Gafford - Click image for larger view

The transit of Venus -- rich in tradition and important in the development of man's understanding of the solar system and the universe -- is one of those milestone, once-in-a-lifetime events that everyone interested in astronomy should see in person.

In Denver, the transit was observed at Chamberlin Observatory with DU's 20-inch Clark-Saegmuller refractor, as well as with telescopes attended by members of the Denver Astronomical Society in Observatory Park and at the Denver Museum of Nature and Science, from 4pm to about 8pm, when the ongoing transit set in the west.

An additional treat for the transit was the high activity of the Sun, which is at maximum, with frequent sunspots and solar prominences. Although there were clouds to the west, the first 45 minutes of the transit were clearly visible and there were numerous gaps in the clouds throughout the day, especially in the early evening.

People viewing Venus Transit at DMNS, June 6, 2012  Boy viewing Venus Transit at Chamberlin Observatory 
Viewing Venus Transit at the DMNS 
(Courtesy Chuck Habenicht, DAS)
Boy viewing the Transit at Chamberlin Observatory
(Courtesy Ron Pearson, DAS)

The transit is a seemingly simple event: the crossing of sun's disk by the planet Venus. But it is also a rare one, occurring twice (8 years apart) at intervals of about 113 years.  The previous transit of Venus (not visible from the Western U.S.) was on June 8, 2004. The next transits will be in December of 2117 and 2125. The 2012 transit will be only the 8th since the invention of the telescope and the first to be widely visible to the U.S. public because of the wide availability of safe, solar filters.

DO NOT LOOK DIRECTLY at the Sun without proper eye protection. Read NASA Article

Transit Events

In Denver, CO (and the rest of the Western U.S.) the Sun set before the transit was finished (External Egress). The following events were visible from Observatory Park and DMNS (from the Chamberlin Observatory dome the Sun will be visible until about 7:15pm):

External Ingress Internal Ingress Greatest Transit Internal Egress External Egress
4:05:19 pm MDT 4:22:55 pm MDT 7:25:44 pm MDT Not Seen Not Seen
    Observer's Handbook 2012, RASC


Check out the DAS Mercury Transit of 2006 Web page for information on Denver observations of a similar but more frequent planetary transit.

NASA Web Site and Online Viewing, which includes articles on the scientific and cultural significance of the transit of Venus:

Safety and access considerations for Chamberlin Observatory.



The Denver Astronomical Society
DAS Home Page