May 28, 2020

Review: Two Essential Transit of Venus Books!

This week, we’re going to break from convention and we’re giving you an early review and a shoutout of two fine and indispensible resources for the upcoming transit of Venus on June 5th-6th. This is the last such transit of our sister world for this century, and over the years we’ve reviewed two fine books on this unique event: The Transits of Venus by William Sheehan & John Westfall and The Day the World Discovered the Sun by Mark Anderson.

We had a chance to catch up with author John Westfall recently about all things transit related. Mr. Westfall provided us with some fascinating insights into the history of transits and what to expect this coming Tuesday (or Wednesday if you reside across the dateline). Current transits occur in 8 year pairs separated by alternating longer periods of 105.5 and 121.5 years, and we were interested to find out that this is only true in the current epoch. For example, single transits have occurred in 1396, and another will happen in 3089.

Arm yourself with knowledge: The Day The World Discovered the Sun & The Transits of Venus!

Mr. Westfall also regaled us with the checkered history of transit chasing, which is in and of itself a fascinating snapshot of the history of astronomy. Fascinating footnotes and anecdotes abound; for example, did you know that American astronomer David Rittenhouse passed out at the start of the 1769 transit? One of his tales and the inspiration of the book revolved around the Jean-Baptiste Chappe expedition to San Jose del Cabo in Mexico to observe the same transit. Beset by disease and the whims of 18th century travel, Chappe successfully observed the transit and an eclipse of the Moon to gain a fix on their longitude, only to die of typhus shortly after. The author first heard of this tale during a 1991 expedition to Baja to observe a solar eclipse, and this tale and more is recounted in his book and The Day the World Discovered the Sun.

But those astronomers centuries ago successfully risked life and limb to gather the data that would lead to the solar parallax and the scale of the solar system. The author also discussed another fascinating topic; how those old-time astronomers observed the Sun. This was done by use of smoked or colored glass (highly dangerous!) or the more sane method of projection. It was noted that while the Chinese kept extensive observations of sunspots visible in pre-telescopic times, the dates of such observations do not match up with any transits of Venus.

The author (and myself) are also making plans to observe the 2012 transit, and discussed unique features such as the aureole (or ring) and black drop effect to watch out for during ingress and egress onto and off of the solar limb. Mr. Westfall notes that the aureole was photographed for the first time in 2004 (photography was in its infancy in 1882). Online sites such as the Sun-monitoring Global Oscillation Networking Group (GONG) should be great resources to monitor the transit worldwide.

Another burning question that provided an interesting discussion earlier this year via Twitter also came up; transits in popular culture. While the sci-fi movie Sunshine depicts a transit of Mercury and solar eclipses have appeared in film with various degrees of accuracy, we’ve never seen a transit of Venus in cinema (although as we pointed out in its recent review, The Day the World Discovered the Sun reads like a historical novel and would make a fine movie!) Mr. Westfall brought to our attention Shirley Hazzard’s novel The Transit of Venus, in which the term is used in metaphor, and John Phillip Sousa’s novel of the same name, which apparently is less than stellar. (Sousa also wrote The Transit of Venus March).

Next week’s event will definitely be something special, and if the recent annular solar eclipse is any indication, some mind-blowing photography is in store. The author noted in closing that Point Venus, Tahiti will also see the 2012 transit, the same locale that Captian Cook’s expedition observed from in 1769. And the author’s dream spot from which to view 2012 transit? Darwin, Australia, which offers a transit almost directly overhead with statistically the best chances for clear skies. Hey, stick around in Australia and you’ll see two more solar eclipses (one on November 13th and one on May 10th) in the next year!

Do seek out The Transits of Venus and The Day the World Discovered the Sun for some great summer reading leading up to next week’s transit of Venus and one of the rarest of astronomical events!


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