Tuesday, June 5, 2012

transit... Venus... Kepler

The Internet, TV news shows and today’s Chicago Tribune, are all abuzz  telling us to look skyward today when Venus passes in front of the sun (like a mini-eclipse).  It’s called a transit and here is the definition:

  1. The passage of a smaller celestial body or its shadow across the disk of a larger celestial body. As observed from Earth, Mercury and Venus are the only planets of the solar system that make transits of the Sun, because they are the only planets with orbits that lie between Earth and the Sun. Mercury makes an average of 13 transits of the Sun each century. Transits of Venus across the Sun are much rarer, with only 7 of them having occurred between 1639 and 2004.

I took particular interest because of Johannes Kepler.  As I noted in one of my blogs about sabbatical books, on my ‘to read’ list this summer is Kepler’s Witch, An Astronomer’s Discovery of Cosmic Order Amid Religious War…etc. Kepler was  mentioned in the article from today’s Trib:

“Johannes Kepler, the famed mathematician-astronomer, was the first to predict a transit of Venus, calculating correctly that one would occur in 1631, though he died a year too soon to see it. Its twin transit, in 1639, was recorded by two witnesses, and it helped scientists better understand Venus' orbit.”  --Eryn Brown and Amina Khan, Tribune Newspapers.

Today's transit, which bookends a 2004-2012 pair, begins at 5:09 p.m. CDT and lasts for six hours and 40 minutes. Times can vary by seven minutes depending on the location of the observer.

I’ll be watching… won’t you?  And I’ll be reading about Kepler, too!


  1. The kids and I WILL be watching! (and watching for your next blog post)

  2. Thanks for the reminder! Lily and I will be heading out to see if we can see it through a makeshift pinhole camera.