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June 8 2004 Parramatta High School 150°59'44"East 33°49'15"South |
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Click here to view the gallery. |
 Captain James Cook ponders his voyage. |
Hands up if you have personally witnessed a transit of the planet Venus in front of
the face of the sun... (prior to 2004, that is) Your hand is up?... Liar!
The last Transit of Venus was on December the 6th, 1882.
They're not very common. Here is a list of the last few and the next few transits:
1631, December 7 |
| A Transit of Venus occurs when the planet Venus passes directly between the Earth
and the Sun. The appearance, on Earth, is that of a small black disc passing slowly
across the blazing face of the sun. Because of the relative inclinations of the planes in which Earth and Venus orbit the sun, these transits are few and far between. Celestial mechanics dictate that they occur in eight-year pairs, as can be seen from the list of dates above. Mercury, the planet closest to the sun, transits a little more often. Parramatta High School observers recorded Mercury's most recent transit on May 7 2003. Whilst the transit of Mercury was an impressive sight, Venus should present an easier-to-see and hence more impressive sight, as its disc is well over twice the apparent diameter of Mercury. |
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The Cook Connection
James Cook, like most intelligent men with an enquiring mind, was an
astronomer in his own right. In 1768 he was selected, partly on the basis of his
knowledge of astronomy to captain a voyage to Tahiti to make an observation of the
transit of Venus.
Edmund Halley (of comet fame) had predicted the transit on June 3 1769. Best conditions
for viewing were to be in the South Pacific, so Tahiti was selected
(a tough assignment, but someone had to do it.)
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| After observing the 1769 transit, Cook then allegedly opened his sealed orders, and, on
the instruction of his masters, proceeded to "discover" Australia and New Zealand for the
greater glory of the Empire. So you see, transits of the planet Venus, rare as they are, play a pivotal role in the history of our country. Just four transits later we, at Parramatta, are ready to observe this twice-in-a-lifetime celestial phenomenon. |
| Details of the Transit from Parramatta | |
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At 3:07:12pm on Tuesday June the 8th 2004, Venus will make first contact with the
disc of the sun. Sadly, this event will not be visible for us, as we will be viewing the event in white light, on a computer monitor and/or by projection. The disc of Venus will be utterly washed out by the intense brightness of the Sun. Lucky observers using hydrogen/alpha filters will have been able to observe the close approach of Venus to the Sun, as it would be silhouetted against the Sun's prominences (visible only with h/a). However, a few scant seconds later we should be able to see a tiny "bite" taken out of the Sun as Venus commences its transit. |
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Some 18 minutes later Venus will make second contact. This means that the entire disc of the
planet will be outlined at the edge of the Sun. The disc of Venus will be easy to see now. Hopefully we will be able to observe the "fuzzy" edge of the atmosphere around Venus.
Now is probably an appropriate time to remind all readers: |
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 The exact moment that Venus "breaks free" from the inner edge of the disc of the Sun will probably be difficult to determine accurately, as Venus' atmosphere will produce a "tear-drop" effect - effectively stretching the event for a few moments. The animation at right shows the "tear-drop" effect, a little exaggerated. |
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Then, tragedy-on-tragedy! At about nine minutes to five pm the sun will set at
Parramatta, with the transit barely one-third over. Short of relocating in the Indian Ocean, or the northern hemisphere, we will have then seen the end of this transit.
Cloud cover and other disastrous interruptions notwithstanding, PHS observers will
(as usual) post photos of this transit as soon as they are available. |
For lots of good information on captain Cook's telescopes, visit: http://www.antiquetelescopes.org/cook.html (external site).
More on the transit at: www.transitofvenus2004.org.uk and http://www.transitofvenus.org (both external)
More! This time from the Smithsonian Institute
View Parramatta High's observations of past celestial conjunctions:
The partial solar eclipse of November 24 2003
The transit of Mercury on May 7th 2003
The total solar eclipse of December 4 2002,
and many more, lunar, stellar and so on, indexed here.
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Break out
of this frame. |
