Re: Off topic: transit of Venus in about 1770
Dear Dave, WOW! What a great response. Everything I ever wanted to know, and in such a way that I could understand. Many thanks for the URL and for the notes there. Wonderful stuff. Now all I have to do is convince the Australian government to send me to say, Kamchatka to observe a transit. Yes, I know it is very cloudy, but they don't. But it is a wonderful landscape! Cheers, John. Dr John Pickard Senior Lecturer, Environmental Planning Graduate School of the Environment Macquarie University, NSW 2109 Australia Phone + 61 2 9850 7981 (work) + 61 2 9482 8647 (home) Fax + 61 2 9850 7972 (work)
Fw: Off topic: transit of Venus in about 1770
Cook's was one of many astronomical expeditions attempting to observe the 1769 Venus transit. The objective was to measure the solar parallax which is a fundamental quantity for determining the distance from the Earth to the Sun (1 astronomical unit) and, hence, all distances and dimensions in the solar system. Basically, the problem was to time the exact instant when Venus' disk enters the solar disk from as many different places on Earth as possible. The technique used was first described by Edmund Halley in 1716. Several observations were made of the 1761 transit and even more in 1769. Cook, who was a pretty good astronomer in his own right, escorted a group to Tahiti. Other groups went to California (Chappe), San Domingo (Pingre), Hudson Bay (Wales), Siberia (Vardoe) and still others observed from their home observatories. The values measured for the solar parallax varied from 8.55 sec to 8.88 sec., which is very close to the true value and a great improvement over previous values. Note that the accuracy of the measurements was greatly enhanced by tremendous progress in the 18th century in determining the size and shape of the Earth itself. Best regards, Jim James E. Morrison Astrolabe web pages at: http://myhouse.com/mc/planet/astrodir/astrolab.htm -Original Message- From: John Pickard <[EMAIL PROTECTED]> To: sundial@rrz.uni-koeln.de Date: Monday, March 15, 1999 8:33 PM Subject: Off topic: transit of Venus in about 1770 Greetings all, When I was a kid at school more years ago than I care to remember, I was taught that Lieutenant James Cook RN came out to Australia in 1770 (or was it 1772??) to have a look around, and also to observe the "transit of Venus" in Tahiti. OK, I know what the ToV is, but why go half-way round the world at great expense and logistic difficulty just to see it? No one ever explained this to me. Apparently the education department assumed that it was self-evident! So my question (which I am sure will be answered) is simple: why would anyone cross the road (let alone the world in a small sailing ship) just to see a ToV? Thanks, John Dr John Pickard Senior Lecturer, Environmental Planning Graduate School of the Environment Macquarie University, NSW 2109 Australia Phone + 61 2 9850 7981 (work) + 61 2 9482 8647 (home) Fax + 61 2 9850 7972 (work)
Even Further Off topic: transit of Venus in about 1770
And for a discussion of the transit of Venus, teaching astronomy, and love, read Stephen Leacock's short story "The Transit of Venus." :-) On Mon, 15 Mar 1999, Dave Bell wrote: >On Tue, 16 Mar 1999, John Pickard wrote: > >> When I was a kid at school more years ago than I care to remember, I >> was taught that Lieutenant James Cook RN came out to Australia in >> 1770 (or was it 1772??) to have a look around, and also to observe >> the "transit of Venus" in Tahiti. >> >> So my question (which I am sure will be answered) is simple: why >> would anyone cross the road (let alone the world in a small sailing >> ship) just to see a ToV? >> >> Thanks, John >> Dr John Pickard >> Senior Lecturer, Environmental Planning >> Graduate School of the Environment >> Macquarie University, NSW 2109 Australia > >John: > > Your question intrigued me, as I had always just accepted the bare >statement, and hadn't thought about *why*, at least that I can recall. > > Certainly, one part of the question - "why travel so far?" is clear. The >event, like a lunar eclipse, is not visible from all parts of the Earth. >In fact, it is slightly more like a total solar eclipse, in that one's >position on the Earth affects the view, by parallax. > > The big question though, is "Why did they care?". Seems the project was >basically to determine the radius of the Earth's orbit, still undetermined >in the late 18th century. > > Check out: > >http://www.dsellers.demon.co.uk/index.htm > >Dave > > === Richard B. LangleyE-mail: [EMAIL PROTECTED] Geodetic Research Laboratory Web: http://www.unb.ca/GGE/ Dept. of Geodesy and Geomatics EngineeringPhone:+1 506 453-5142 University of New Brunswick Fax: +1 506 453-4943 Fredericton, N.B., Canada E3B 5A3 Fredericton? Where's that? See: http://www.city.fredericton.nb.ca/ ===
Re: Off topic: transit of Venus in about 1770
On Tue, 16 Mar 1999, John Pickard wrote: > When I was a kid at school more years ago than I care to remember, I > was taught that Lieutenant James Cook RN came out to Australia in > 1770 (or was it 1772??) to have a look around, and also to observe > the "transit of Venus" in Tahiti. > > So my question (which I am sure will be answered) is simple: why > would anyone cross the road (let alone the world in a small sailing > ship) just to see a ToV? > > Thanks, John > Dr John Pickard > Senior Lecturer, Environmental Planning > Graduate School of the Environment > Macquarie University, NSW 2109 Australia John: Your question intrigued me, as I had always just accepted the bare statement, and hadn't thought about *why*, at least that I can recall. Certainly, one part of the question - "why travel so far?" is clear. The event, like a lunar eclipse, is not visible from all parts of the Earth. In fact, it is slightly more like a total solar eclipse, in that one's position on the Earth affects the view, by parallax. The big question though, is "Why did they care?". Seems the project was basically to determine the radius of the Earth's orbit, still undetermined in the late 18th century. Check out: http://www.dsellers.demon.co.uk/index.htm Dave
Off topic: transit of Venus in about 1770
Greetings all, When I was a kid at school more years ago than I care to remember, I was taught that Lieutenant James Cook RN came out to Australia in 1770 (or was it 1772??) to have a look around, and also to observe the "transit of Venus" in Tahiti. OK, I know what the ToV is, but why go half-way round the world at great expense and logistic difficulty just to see it? No one ever explained this to me. Apparently the education department assumed that it was self-evident! So my question (which I am sure will be answered) is simple: why would anyone cross the road (let alone the world in a small sailing ship) just to see a ToV? Thanks, John Dr John Pickard Senior Lecturer, Environmental Planning Graduate School of the Environment Macquarie University, NSW 2109 Australia Phone + 61 2 9850 7981 (work) + 61 2 9482 8647 (home) Fax + 61 2 9850 7972 (work)
