2012 Transit of Venus from Australia

By Fred Watson 31 May 2012
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It’s the last chance to see the Transit of Venus for 105 years, so here’s all you need to know about this rare event.

Fred Watson is astronomer-in-charge of the Australian Astronomical Observatory (AAO) and writes a regular column for Australian Geographic. This story was first published in the Apr-Jun 2011 issue of the journal. Find more of Fred’s stories here.

IF YOU’RE PLANNING to watch the transit of Venus on 6 June, 2012, modern technology has made you better equipped than anyone has ever been in observing this rare phenomenon. Even the transit of June 2004 could not boast some of the bells and whistles that today’s would-be transit observer has to play with. And anyone who had seen the previous one, in December 1882, would have regarded the facilities we have at our disposal today as little short of magical. 

Why is it such a big deal? Venus only passes between the Sun and the Earth twice (eight years apart) every 100 or more years. The 2012 transit is the second recent one, so if you miss it, the next chance is in December 2117!

But to start with, we in Australia have the great good fortune to be able to see the transit – which looks like a small, black disc crossing the Sun’s path – in its entirety (except for those on the west coast, for whom the transit will already be in progress as the Sun rises). Details are given in the timetable below.

(Courtesy of the Astronomical Society of Australia)

Seeing the 2012 Transit of Venus

Observing the transit at home needs not only clear weather, but also a safe way of magnifying the image of the Sun. Unless you have purpose-made solar filters, you must never look directly at the Sun, event through a telescope or binoculars, as serious eye-damage will result.

The best method is what is known as ‘eyepiece projection’. Here, the telescope or binoculars must be set up on a tripod or other suitable stand, and aligned with the Sun (yes, without looking through the instrument!). It takes a little practice, but if you can place a sheet of card behind the eyepiece, and shade it from the direct light of the Sun, you will find that a magnified image will be formed there. A bit of judicious focusing will allow it to be sharpened up enough to see the Sun clearly, along with any sunspots present and – on 6 June -a transiting planet.

Failing that, or if the weather is cloudy, the transit will be shown on many of the websites that are planning to stream the event live. For example, there will be coverage on NASA’s website, while locals can visit Australia’s Siding Spring Observatory near Coonabarabran, NSW.

2012 Transit of Venus smartphone app

But perhaps the most remarkable piece of technology now available is a smartphone app that will allow modern day observers to emulate James Cook in providing their timings of the start and end of the transit.
Whereas just a handful of observers watched the 1769 transit, this app will allow hundreds of thousands of transit-watchers to submit their timings to a central site for analysis. Have a look, and have fun!

(Credit: Fred Espenak/NASA)

VIDEO of the Transit of Venus, by NASA.