Thu, 24. May 2012
Transit of Venus - Coming Up On 6th June
There will be a rare transit of Venus on Wednesday 6th June, between 8.16 am and 2.44 pm AEST.
Australia and New Zealand will get the best views of this transit, with the transit ending at sunset in New Zealand, providing some great photo opportunities over there. I shall have my two solar telescopes and a camera trained on the Sun, hoping that our persistent cloudy weather will not wipe the event out completely.
Warning: Looking directly at the sun, without certified solar filters, will cause permanent blindness.
VENUS TRANSIT HISTORY:
Venus transits are very rare events. They come in pairs and this one will complete only the fourth pair to be observed since the invention of the telescope. Transits have occurred in:
1631 & 1639
1761 & 1769
1874 & 1882
2004 & 2012
The earlier of these transits were invaluable to astronomers in establishing the size of the Astronomical Unit (Earth-Sun distance), using the parallax method. They also helped establish that an atmosphere existed on Venus.
There were no transits of Venus during the twentieth century and the first of the current transit pair came eight years ago. I missed it, having just started a new job. This transit will be the last opportunity for any of us to observe an event which has been seen only seven times previously. The next transits of Venus will not occur until:
2117 & 2125
2247 & 2255
2360 & 2368
MERCURY TRANSITS:
The Venus transit event got me thinking of Mercury transits. These are more common, as there were fourteen during the twentieth century and there have been two so far this century:
2003 & 2006.
The next four Mercury Transits will be:
2016, 2019, 2032 & 2039.
SIMULTANEOUS TRANSIT EVENTS:
Transits of Venus and Mercury together are of course extremely rare. According to Wikipedia, the last simultaneous occurrence of Mercury and Venus transits occurred in 373,173 BCE. The next simultaneous event will not occur until the year 69,163 CE. Imagine the clouds rolling in after a lifetime of waiting to watch that. You would then have to wait until 224,508 CE for the next one!
Before then, however, in 13,425 CE a nearly concurrent transit event is predicted: transits of Mercury and Venus will follow one after the other, within an interval of only 16 hours.
The simultaneous occurrence of a solar eclipse and a transit of Mercury is also very rare. The last time this happened was in 6945 BCE. The next solar eclipse occurring during a transit of Mercury will be 6757 CE.
This article was submitted for inclusion in the May edition of Prime Focus but was not selected for publication.
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