Talk:Transit of Venus

2012 transit

Are there any plans to have this article featured on the main page on the day of the 2012 transit? Although it has appeard once before I'm sure a case could be made for annother appearance on the day as it's only a twice in a lifetime event. Richerman (talk) 14:58, 12 January 2012 (UTC)

Resonance?

I think that the term "resonance" should not be used and especially "243:395 resonance" does not make much sense, since "orbital resonance occurs when two orbiting bodies exert a regular, periodic gravitational influence on each other, usually due to their orbital periods being related by a ratio of two small integers." Venus does not have any gravitational influence on the Earth and the integers are not small. The given source also does not speak about any "resonance" of the two bodies. Jan.Kamenicek (talk) 01:25, 5 March 2012 (UTC)

We are talking here about near resonances, which are a far cry from true resonances. Please review the definition of a near resonance in orbital resonance. While the integers related to true resonances are usually small, that is not always the case; here is a paper that mentions a 53:54 orbital resonance between Saturn's moons Prometheus and Atlas:

• Spitale, J. N.; Jacobson, R. A.; Porco, C. C.; Owen, W. M., Jr. (2006). "The orbits of Saturn's small satellites derived from combined historic and Cassini imaging observations" (PDF). The Astronomical Journal. 132 (2): 692–710. Bibcode:2006AJ....132..692S. doi:10.1086/505206.{{cite journal}}: CS1 maint: multiple names: authors list (link)

For a near resonance, the ratio can be any pair of integers whatsoever. Additionally, it is not true that Venus has no gravitational influence on the Earth; according to the law of gravitation, it must have some influence. Finally, consider the author's descriptions: "Also Venus orbits the Sun just a bit faster than 8 thirteenths of a year, more like 7.997. As we shall see this is a small but crucial difference." and "A closer approximation to the orbit time of Venus is 243/395 years, which by similar logic leads to a longer run 243 year cycle." These are precisely the definitions of the near resonances involved in the transit cycle. WolfmanSF (talk) 05:27, 6 April 2012 (UTC)

In this context, "commensurability" is an equivalent although less accessible term. WolfmanSF (talk) 22:41, 6 April 2012 (UTC)

Does any serious source talk about near resonance (or commensurability) between Venus and the Earth?Jan.Kamenicek (talk) 00:17, 16 April 2012 (UTC)

• This source talks about a near 13:8 orbital resonance, which is of minor interest because of the regular recurrences of favored conjunctions. There was also a publication regarding a spin-orbit resonance between the Earth and Venus's core. But that's probably not what you are looking for. Regards, RJH (talk) 01:24, 16 April 2012 (UTC)
  • Thank you. So if it is of minor interest, it should probably not be emphasized in the lead of the article. Jan.Kamenicek (talk) 19:19, 26 April 2012 (UTC)
    • There are other articles, such as this one:

Bazsó, A. (2010-04-07). "A survey of near-mean-motion resonances between Venus and Earth". Celestial Mechanics and Dynamical Astronomy. 107 (1). Springer: 63–76. arXiv:0911.2357. Bibcode:2010CeMDA.107...63B. doi:10.1007/s10569-010-9266-6. Retrieved 2012-03-01. {{cite journal}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)

• • • Somehow, my point has been missed. These near resonances or near commensurabilities are not of minor interest in this context. They are an essential part of the explanation for the unusual recurrence pattern of the transits of Venus, and it is the rarity of the transits that has made this recent event so newsworthy. WolfmanSF (talk) 03:10, 7 June 2012 (UTC)

TFA for the June transit

As the transit of 2012 will be the last one in the lifetime of anyone alive today I've asked the Features Article Editor if this article could go on the front page on 5th of June and he said he'll consider it - see [1]. It would be good if anyone with the article on their watchlist could read through it again and fix any problems they find before then. Richerman (talk) 17:11, 9 May 2012 (UTC)

Great idea. It might even be good to have it on June 4, to give people a chance to plan for it? Anyway, one thought I had is that the External Links list is rather long -- 16 links, which reads as overwhelming overkill ( a dozen is more than enough). I vote either delete some, or separate the list into two, with the second half of the list being about the June 5/6 tranist and how to view it from one's computer, etc. Softlavender (talk) 12:34, 20 May 2012 (UTC)

OK, I sorted and trimmed the ELs and got them down to 10. Even so, there are one or two which still seem questionable. I mean how important, for instance, is the Nan Madol meridian? Softlavender (talk) 13:07, 20 May 2012 (UTC)

I agree, it's a link farm and I see it's still having links added that really belong on the Transit of Venus, 2012 article. Actually, I have another plan - to write a piece for the "in the news" section and get it running a few days before the transit. Mind you, it's a waste of time talking about anything on this talk page - nobody seems in the least bit interested about doing anything or even replying to posts. Richerman (talk) 22:25, 20 May 2012 (UTC)

I'm new to this topic but agree that it deserves cleaned-up articles (and I've done a couple of trivial things). I normally strongly oppose external link abuse, but I have found that it is often not worth overdoing it when a significant event is due (particularly one of scientific interest). So long as links do have some useful info that is not just a duplicate of the article or other links, I wouldn't worry about them until July. Richerman (talk) 09:38, 21 May 2012 (UTC)

I gather we do not have a more detailed outline of the process involved in going from transit observations to measuring the Earth–Sun distance, and it would be nice if something could be added: not the precise mathematics but a mixture of elementary math and prose with values observed at the time would be very interesting. I've started accumulating the info, but I haven't yet gone to the trouble of finding a proper account in a book. Johnuniq (talk) 02:09, 21 May 2012 (UTC)

Richerman -- please leave the links on the June 5/6 transit. No one, repeat no one, is going to be looking at the practically non-existent sub-article on it. The only way to help people be able to view or find the transit in time is to post the viewing links on this article. A few months down the line, we can (re)move some of links that were only links for viewing. Right now, the ELs are down to a pretty OK number, and well-organized. I've deleted all the spam, dead links, and irrelevancies, and moved the ridiculously obscure ones to the other article, but the main ones about the June transit definitely need to stay here (as well as on that tiny article). Softlavender (talk) 03:23, 21 May 2012 (UTC)

OK, it looks fine now you've cleaned it up - it was a mess before. I agree the 2012 links can go after the event. I think the ToV 2012 article needs some attention though - there's nothing about the work that's going to to be done such as this. There's also been some discussion on my talk page about the possibility of doing some sub articles here Richerman (talk) 09:38, 21 May 2012 (UTC)

Thanks for the 2012 research section. I've copyedited it, added some more refs, and also repeated it on this article because it needs to be readily visible. In terms of the 1769 transit, that definitely needs its own article. Mark Anderson and Andrea Wulf cover the 1769 transit very thoroughly, and in an understandable way, in their 2012 books (see "Further Reading" section). Some of the other books in that list do too (Lomb, Sheehan, etc.), but do not concentrate exclusively on it. I haven't read Wulf yet, but I'm reading Anderson now, and since he's an astrophysicist his info is reliable. Softlavender (talk) 22:24, 21 May 2012 (UTC)

Hmmm, I'm not sure that moving a block of new text from the sub article into a the main article (especially when it's a featured article) is really the right thing to do, but we'll see what others think. I know you're trying to get everything into the main article in case people don't click on the sub article but I don't think that's really the way to go. The 2012 section in the main article should only have a summary of what's in the sub article with just enough to make the reader want to read that one, otherwise there's no point in having a seperate article. Anyway, if the FA director does decide he's going to feature the main article on 5 June, I'll write the "In the news" piece to point to the 2012 article, so it's important to get that one improved. Richerman (talk) 22:49, 21 May 2012 (UTC)

That's actually not true about main vs. sub, especially for an ongoing or current event. There's no Wikipedia stricture about duplication of text across articles that cover the same subject matter (in fact it's very common), and the main article that incorporates the current event needs to include the most relevant information; the sub article contains detailed viewing and timing info. The main article needs to have substantial scientific information about this ongoing/current event. See for instance, the Transit of Venus, 2004 vs. Transit of Venus#2004. Softlavender (talk) 23:06, 21 May 2012 (UTC)

Observing safely

As it stands, the article is inadequate for us lower-level amateurs. Safety warnings are needed; I added a heading to make these warnings easier to find. However, the current version is oriented to solar eclipses. You can see a solar eclipse without magnification by projecting thru a pinhole onto a screen, etc. A Venus transit is different, if I understand correctly; magnification of some sort will be necessary. So the article needs improvement here. Someone on the Web has probably done a decent job with this. Oaklandguy (talk) 19:38, 24 May 2012 (UTC)

Actually there shouldn't really be any warnings, technically, as wikipedia is an encyclopaedia, not a 'how to' manual (see: wp:wikipedia is not). But personally, I wouldn't like to think anyone was blinded because they'd read this article and not realised the dangers. A transit can be viewed without magnification if you've got good eyesight, either with eclipse glasses or a pin hole camera type of arrangement. There are lots of websites explaining how, but one of the best places to find information is the Transit of Venus group on facebook at http://www.facebook.com/groups/108400462513165/ Richerman (talk) 23:41, 24 May 2012 (UTC)

Good God! I've just seen those awful safety illustrations. I don't think they are at all necessary and they are moving this article a long way from its featured article status. Apart from that, the warning with them is totally ungrammatical and says nothing about viewing the Sun with the naked eye. I've removed them for now but can we have some discussion about this? This article will be appearing on the main page on 5 June and it's beginning to look a complete mess. Richerman (talk) 23:57, 24 May 2012 (UTC)

It is kind of important to have clear observing safety information, atleast in the lead up to this transit (can always be removed after the transit to maintain "featured article" standards). Ought to be well sourced to reliable secondary sources, but the current section underplays the danger to a lay audience. The text should make the precautions more straight forward. SkyMachine ⁽⁺⁺⁾ 00:47, 25 May 2012 (UTC)

I agree the safety info should be clearer (and that the removed illustrations are not helpful). I tried, but really wanted to start with something like "looking at the Sun can cause blindness, and looking at the Sun through binoculars will cause blindness". Might find refs at Sun gazing. Tricky while maintaining normal writing standards. Johnuniq (talk) 00:52, 25 May 2012 (UTC)

I agree they're not too good at the moment and I'll be happy to have a look at rewriting them tomorrow if nobody else does it, but as it's 2am here I'm off to bed. I'm sorry if my remarks about the drawings were a bit intemperate, someone with good intentions has obviously worked hard to produce them. They'd be fine for a product warning on a telescope or whatever but not here. I've also read that modern welder's masks are not safe for viewing the Sun. I expect that one of the reasons for not giving safety advice here is that you can't be sure it's right. Richerman (talk) 01:06, 25 May 2012 (UTC)

Exactly. I was going to change the goggles caption to insert "safely" but then realized that I have never researched the safety issues involved, nor the standards of goggles that might be available world wide. I'm prepared to say (or use a source) that looking at a focused image is safe, but it would be best to not use Wikipedia's voice to assert that some method of looking at the Sun is safe. Johnuniq (talk) 02:37, 25 May 2012 (UTC)

Some good info here. SkyMachine ⁽⁺⁺⁾ 02:42, 25 May 2012 (UTC)

Thank you, SkyMachine. Also - if I understand Ralph Chou correctly:

• magnification might not actually be necessary
• welding goggles - some 14's are fine but not necessarily all

Oaklandguy (talk) 06:21, 25 May 2012 (UTC)

Reflective metal coated mylar (as found in eclipse viewing glasses) can be used for direct observation but the disk of Venus will appear tiny without magnification. SkyMachine ⁽⁺⁺⁾ 06:59, 25 May 2012 (UTC)

As I said you need to have good eyesight. Richerman (talk) 08:31, 25 May 2012 (UTC)

Hughhunt (talk) 07:58, 25 May 2012 (UTC) This is a great page! For the 2004 transit I used a 'reflected pinhole' method which was very safe and was great for showing the transit to large groups of people. See here . It has the additional advantage of being VERY cheap and accessible to anyone - even kids can do it. Might a description of this be appropriate on this page? I don't want to make changes if they're not appropriate.

Not really, best to just add it as a reference in the safety section for the pinhole method or to external links. If you already have a telescope, a sun funnel is an excellent and cheap method see: http://transitofvenus.nl/wp/observing/build-a-sun-funnel/ although not all telescopes can survive being pointed at the Sun without damage. By the way, your signature should go at the end of your post :-) Richerman (talk) 08:31, 25 May 2012 (UTC)

The link provided by Hughhunt above ([2]) shows an excellent procedure that should be mentioned in the article. We should not pad out the "Observing" section with too many how-to violations, but I'm going to play with some text to see if major methods can be mentioned. Something like this:

An image of the transit can be viewed in a darkened room using a reflection of the sun from a small mirror mounted outside a window.[ref]

Any thoughts? Johnuniq (talk) 10:51, 25 May 2012 (UTC)

That looks ok to me. Richerman (talk) 11:09, 25 May 2012 (UTC)

OK, I've made a minor change using ref, as suggested by Johnuniq, hope it's OK (and thanks for the welcome and user tips!) Hughhunt (talk) 09:11, 26 May 2012 (UTC)

TFA for 5 June 2012

The Queen of England has graciously moved aside so that this article can be TFA for June 5. This is only the second time in the history of wikipedia an article has been TFA twice - which makes it an historic event in three different ways.Richerman (talk) 23:24, 24 May 2012 (UTC)

The text at Wikipedia:Today's featured article/June 5, 2012 should have a brief mention of the historical significance of the event as being the first "measure" of the solar system (a gigantic intellectual leap). We can't fiddle with the wording too much, but some tweaking over the few days should be possible. Johnuniq (talk) 11:58, 25 May 2012 (UTC)

To keep the text from getting much longer I would suggest replacing the sentence that reads "The periodicity is a reflection of the fact that the orbital periods of Earth and Venus are close to 8:13 and 243:395 commensurabilities" with something like the sentence from the lead that reads "Venus transits were historically of great scientific importance as they were used to gain the first realistic estimates of the size of the solar system". I think that sentence that's there now is too technical for the general blurb and may put people off reading the article. What do you think? Richerman (talk) 18:25, 25 May 2012 (UTC)

Current blurb

Proposed blurb

A transit of Venus across the Sun takes place when the planet Venus passes directly between the Sun and Earth, becoming visible against (and hence obscuring a small portion of) the solar disk. During a transit, Venus can be seen from Earth as a small black disk moving across the face of the Sun. The duration of such transits is usually measured in hours. A transit is similar to a solar eclipse by the Moon. While the diameter of Venus is almost four times that of the Moon, Venus appears smaller, and travels more slowly across the face of the Sun, because it is much farther away from Earth. Transits of Venus are among the rarest of predictable astronomical phenomena. They occur in a pattern that repeats every 243 years, with pairs of transits eight years apart separated by long gaps of 121.5 years and 105.5 years. The periodicity is a reflection of the fact that the orbital periods of Earth and Venus are close to 8:13 and 243:395 commensurabilities. The next transit of Venus will be on 5 and 6 June 2012, and it will be the last Venus transit this century. The prior transit took place on 8 June 2004. After 2012, the next transits of Venus will be in December 2117 and December 2125. A transit of Venus can be safely observed by taking the same precautions used when observing the partial phases of a solar eclipse. (more...)

A transit of Venus across the Sun takes place when the planet Venus passes directly between the Sun and Earth, becoming visible against the solar disk. During a transit, Venus can be seen from Earth as a small black disk moving slowly across the face of the Sun. A transit is similar to a solar eclipse by the Moon, but while the diameter of Venus is more than three times that of the Moon it is much further from Earth and so appears smaller and generally takes longer (up to eight hours) to travel across the solar disk. Transits of Venus are among the rarest of predictable astronomical phenomena—they occur in a pattern that repeats every 243 years, with pairs of transits eight years apart separated by long gaps of 121.5 years and 105.5 years. The next transit of Venus occurs on 5 and 6 June 2012, and will be the last Venus transit this century. Historically, Venus transits were of great scientific importance as they were used to gain the first realistic estimates of the size of the solar system. A transit of Venus can be safely observed by taking the same precautions used when observing the partial phases of a solar eclipse. (more...)

It's not a good idea to make frequent edits at Wikipedia:Today's featured article/June 5, 2012, so I have put a proposal above and will wait to see if anyone has comments before putting it in the blurb. Please edit the right hand side or make suggestions below. There is a note at WP:TFAR saying the blurb should be no more than 1200 characters, including wikitext. The current blurb is 1584 characters, and the proposal is 1342.

Is the text "(and hence obscuring a small portion of)" useful? Omit? I find "The duration of such transits is usually measured in hours" a bit indirect, but can't think of an improvement. Johnuniq (talk) 11:14, 26 May 2012 (UTC)

I didn't really see the relevance of that bit either. I've removed it and made a few edits as I found the phrasing to be a bit staccato with a number of short sentences, although you may think that one is now a bit too long. Also, is the phrase "A transit of Venus across the Sun" really necessary? Wouldn't "A transit of Venus" suffice? Richerman (talk) 12:06, 26 May 2012 (UTC)

How about "up to 8 hours"? It tends towards the upper end anyway. Sagittarian Milky Way (talk) 20:03, 26 May 2012 (UTC)

Thanks for the improvements. I have done another edit, but will try hard to not do any more. I used an unspaced em dash which I think is the recommended style (although the article has a mixture of dash styles), and I changed "much farther away from Earth and so appears smaller and travels across the solar disk in a period measured in hours" to read "much further from Earth and so appears smaller and takes longer (up to eight hours) to travel across the solar disk". Is that ok? Is the implication that a TOV always takes longer than a lunar eclipse correct? Johnuniq (talk) 10:41, 27 May 2012 (UTC)

As a matter of interest, I did a very quick script to calculate the durations of all Venus transits from the Six Millennium Catalog. The results follow (showing the sorted durations of each transit in minutes, calculated from the difference between the Contact_IV and Contact_I times):

117, 120, 138, 140, 176, 179, 180, 222, 222, 228, 239, 246, 272, 272, 277, 283, 291, 300, 316, 321, 321, 333, 340, 341, 343, 355, 358, 367, 373, 377, 378, 380, 384, 395, 398, 400, 404, 408, 416, 417, 420, 420, 430, 431, 434, 434, 437, 442, 443, 447, 448, 450, 453, 456, 461, 462, 464, 464, 465, 466, 471, 473, 475, 475, 475, 476, 479, 479, 481, 483, 485, 485, 486, 487, 487, 487, 488, 489

So a weasel word like "generally" should probably be inserted into the claim about durations. Johnuniq (talk) 12:36, 27 May 2012 (UTC)

Yep, add "generally" and I think we're there. Richerman (talk) 20:27, 27 May 2012 (UTC)

I've updated it above, and have updated the blurb at Wikipedia:Today's featured article/June 5, 2012. Johnuniq (talk) 23:23, 27 May 2012 (UTC)

Just chiming in that I don't think articles should run as TFA twice. Unless we're running low. It seems a bit strange to run some articles twice but not others. There's lots and lots of FA articles that still have no run yet. — Preceding unsigned comment added by Harizotoh9 (talk • contribs) 16:51, 30 May 2012

This has been discussed at some length on the FA director's talk page and the position is that he makes the decisions about what will appear on the front page and he has decided that this one will appear on 5 June. Richerman (talk) 17:51, 30 May 2012 (UTC)

Yes, and I'm noting my disagreement with that. --Harizotoh9 (talk) 16:34, 31 May 2012 (UTC)

Excellent explanation

There's an excellent graphic explaining the frequency of transits here Richerman (talk) 08:43, 25 May 2012 (UTC)

Safety precautions

This section has no place in an encyopedia. For example, what relevance will it have in a month. Its like putting a warning on the gun article; "do not place against head". Sorry, not quite, but have been watching this page for years, and while the recent work has been really strong and am just delighted to see it, and commend the efforts to get the TFA; I dont think this section is well placed. Ceoil (talk) 01:35, 26 May 2012 (UTC)

Sure, and it will be removed (or greatly cut back) after June 6. A minor discussion above seems to show agreement that some information is desirable as this page will be extremely widely read for a couple days around that date, and it's inappropriate to tell people that something interesting is happening at the Sun without clearly stating the safety problem. I plan to add a sentence or two (see above). This is one of the rare times that WP:IAR can reasonably be invoked. Johnuniq (talk) 02:28, 26 May 2012 (UTC)

Personally, an this is only my openion, I think the sect will make us look silly and a less detatched voice, seemingly overtly pandering to the types who might point binoculars at the sun. Ceoil (talk) 02:53, 26 May 2012 (UTC)

I can see the headline now "Child blinded after reading wikipedia article". I also had reservations about leaving that section in, but when I thought about it I didn't want to have the responsibility of someone being blinded because I insisted on the warnings being removed. You have to remember that 12 year old kids may be reading it who may not fully realise the dangers. I do, however, think the picture of the eclipse glasses is unneccessary and adds nothing to the information given so I've removed it. If anyone wanted to obtain some they would have to buy them from a specialist supplier - they don't need to know what they look like. Richerman (talk) 12:24, 26 May 2012 (UTC)

I agree with Richerman. I was thinking about the glasses and wondered what they cost, so I Googled around. One site said they had sold out, and a couple of others had interfaces that were too irritating for me to bother with, so I stopped looking. Then I thought about all the great scamming opportunities that occur with a phenomenon such as this. The world is full of counterfeit products from medicines to handbags, so there are bound to be fake glasses available which do not even attempt to meet an appropriate standard, or which contain manufacturing defects rendering them dangerous. I mention this to support my conclusion that it is not a good idea for the article to appear to recommend anything, so I think removing the image is desirable (and it was a bit ugly). The safety information that remains is good, and useful for the innocent. Johnuniq (talk) 10:24, 27 May 2012 (UTC)

13:8 near resonance of Earth and Venus

I've twice added this graphic and had it reverted. It is described in the text, and relates to the twin transits of 8 years. If anyone else wants to fight for inclusion harder than me, be my guest. Tom Ruen (talk) 23:11, 30 May 2012 (UTC)

Viewed from the earth, the motion of Venus makes a pentagrammic figure, crossing inferior conjunction nearly exactly 13 times every 8 years.

I reverted it the first time because you put it right below the main picture and gave it a size of 300px - which just made the article look cluttered. I tried removing the forced image size (which shouldn't really be used anyway), but as a thumbnail image it's still rather large. You then moved it to another position where I thought it looked better but someone else reverted it as not relevant. It's a very nice image, skillfully drawn, but there are already too many images in the article and if another one is to go in, some of the others need to be removed first. For me, that would be no bad thing as I don't think we need lots of very similar pictures of Venus crossing the Sun. However, the image needs to be a bit smaller so that it matches the others for size as a thumbnail and doesn't dominate the article. There also needs to be a reference for the claim that the motion of Venus describes a pentagrammic figure. Richerman (talk) 09:42, 31 May 2012 (UTC)

The main flaw in the image is its hard to see when made small. Maybe I'll experiment and add a SVG export format to draw the path with a significant line-width (and white background). I actually made the image orginally by request on the pentagram article. What makes it pentagrammic versus pentagonal is that sequential superior conjunction dates shift 720/5=144 degrees, so it takes 2 cycles to return to the original angle direction. Here's another representation [3], showing a pentagram itself as the linear path of sequential conjunction directions, also showing the 2004/2012 ecliptic longitude nearly equal after 8 years. It's probably a more useful presentation than the orbital path itself. I don't know who did the first plots like mine, but assume Kepler did, since here's a similar plot of Mars, which doesn't repeat as simply. File:Kepler_Mars_retrograde.jpg. Oh, here's a 1799 plot for Venus. [4], and another from 1756! [5] Tom Ruen (talk) 20:18, 7 June 2012 (UTC)

It's a nice image, but should be described as depicting a near resonance (or near commensurability). WolfmanSF (talk) 07:00, 8 June 2012 (UTC)

First observation from space by human

Should it be worth noting this 'achievement' ? See link - add it to the Modern Observations section for the 2012 part

Humans in ISS will observe transit for first time from space.

http://science.nasa.gov/science-news/science-at-nasa/2012/31may_isstransitofvenus/

Angrytony (talk) 18:09, 1 June 2012 (UTC)

Can be viewed without magnification

The article (here) says the "event can be viewed without magnification using filters specifically designed for this purpose". That point is being discussed at Wikipedia:Reference desk/Science#Transit of Venus. The event can be viewed safely provided a safe filter is used, but would the observer be likely to see the transit? The angular diameter of the Sun is 32 arc minutes, while Venus is 1 arc minute, so there is not much to see. Did anyone manage to see the shadow of Venus through a filter (without magnification) in 2004? Should the text about safety glasses and filters be removed or qualified? Johnuniq (talk) 10:00, 3 June 2012 (UTC)

Optometrist Ralph Chou in his video states that Venus can be resolved without magnification as it is a continuous disk and was able to be seen this way in during the last transit with eclipse glasses. SkyMachine ⁽⁺⁺⁾ 10:27, 3 June 2012 (UTC)

I've added a qualification to this and the 2012 article saying that not much will be seen. Feel free to change it if you don't think it's appropriate. Richerman (talk) 10:42, 3 June 2012 (UTC)

I saw it the last time. It's 73% the area of the smallest feature on the 20/20 line of an eye chart. That doesn't mean you can't see it. 27% of your eye's "pixel" is sun, 73% is black, so it should just appear as a gray point. I thought it was pretty obvious, given it's size. People with 20/17 to 20/10 vision should in theory see it completely black (I guess if the sun is low enough for glare to not cause sun to "bleed into the shadow"), heck some people have even seen it as a crescent. 12.196.0.56 (talk) 17:13, 3 June 2012 (UTC)

Almost four

It says "... the diameter of Venus is almost 3 1/2 times that of the Moon ..." after I just changed it from "four" to "3 1/2". According to the Venus infobox, its mean radius is 6051.8 km. According to the Moon infobox, its mean radius is 1737.10 km. So the ratio of the diameters is (2x6051.8)/(2x1737.10) = 6051.8/1737.10 = 3.4839. I consider it misleading to describe a ratio of 3.4839 as "almost four" when it's actually closer to three. So I changed it, and I'm telling you about it because I will also change it in the blurb that is about to appear on the Main Page for the Featured Article. Art LaPella (talk) 01:09, 4 June 2012 (UTC)

The blurb is at Wikipedia:Today's featured article/June 5, 2012.

It used to say: while the diameter of Venus is almost four times that of the Moon

It now says: while the diameter of Venus is almost 3 1/2 times that of the Moon

The same change has been made in the lead of this article.

I think that's unnecessarily ugly. Assuming the ratio of 3.48 above is correct, I think it would be better to use one of these:

while the diameter of Venus is more than three times that of the Moon

while the diameter of Venus is 3.5 times that of the Moon

The blurb is now protected from editing because it is due for display in 22 hours, so an admin is needed to make a change. I put the first of the above ("more than three") above with this edit (I checked that the wikitext under "Proposed blurb" is identical to what is in the blurb, apart from Art's change). Johnuniq (talk) 02:05, 4 June 2012 (UTC)

I have now confirmed the 3.48 value calculated by Art above (using a source not connected with Wikipedia), and hope that the "more than three times" wording can be used in the blurb and in the lead of this article. Johnuniq (talk) 08:26, 4 June 2012 (UTC)

Changed. Art LaPella (talk) 15:44, 4 June 2012 (UTC)

link to "Transit of Mercury"

This article should be linked to "Transit of Mercury", and vice versa. Don't know how to do it. I'm ideas man. You do it, please. Myles325a (talk) 07:33, 4 June 2012 (UTC)

it is already. Look at the See Also section. SkyMachine ⁽⁺⁺⁾ 07:46, 4 June 2012 (UTC)

Captain Cook, 1769

Should more emphasis be made of the historical significance of James' Cook's observation? e.g "If it weren't for the transit of Venus and Cook's skills as an astronomer, he may not have been in the Pacific in 1770 when he planted the flag on Possession Island, claiming the eastern coast of Australia as British territory." (and I would add: New Zealand too). Adpete (talk) 07:05, 5 June 2012 (UTC)

I've given it a bit more prominence (its own paragraph) and added that then explored Aust and NZ. Adpete (talk) 10:53, 5 June 2012 (UTC)

Fine, but I'm not sure the suggestion about Cook in the above comment is right. Googling for the quoted text led me here. I am no historian, but I think that article is overblown on at least two counts. First, it was a lot more than Cook's observation of the transit that led to Lalande's calculation of the AU value. Second, it is quite likely that Cook's primary mission was to look for Terra Australis—observing the transit was important, but it is not clear that it was the reason for the voyage (accounts differ on that). Johnuniq (talk) 11:47, 5 June 2012 (UTC)

Oops sorry I meant to reference that quote. But no matter, I didn't use it (or anything like it). I decided it was too contentious. All I did was mention that Cook went on to explore Aus and NZ. If nothing else it's historically interesting that the transit was observed as part of such a significant voyage. Adpete (talk) 12:49, 5 June 2012 (UTC)

Chronometry of Early Observations?

I would think that a major issue and limiting factor in early parallax measurement attempts would be the synchronizing of time versus longitude.

Should this be discussed? — Preceding unsigned comment added by 98.180.26.211 (talk • contribs) 07:05, 5 June 2012

I have wondered about that myself. It certainly would of been a problem for the 1761 transit as John Harrison had only just submitted his design for the H4 chronometer and it was some years later before it was accepted. However, I've not found any discussion about this elsewhere and we need a reliable source for it before we can include anything. As it was, the 'black drop' effect precluded any really accurate timed measurements of the 1761 and 1769 transits anyway, and when the next pair came along accurate time keeping wouldn't have been a problem. Richerman (talk) 11:21, 5 June 2012 (UTC)

Richerman has covered the issue, but you could try asking at Wikipedia:Reference desk/Science. One point is that those involved had plenty of time to prepare so the uncertainty may not have been that important (it's not like the navigation problem, but I don't know). Johnuniq (talk) 11:32, 5 June 2012 (UTC)

Transit's longitude

Is venus always crossing sun at the same longitude? (81.197.68.158 (talk) 13:16, 5 June 2012 (UTC))

Full transits are seen from different parts of the Earth on each occasion. They also cross the Sun on different paths each time. Richerman (talk) 13:34, 5 June 2012 (UTC)

Nice timing

Nice timing on the main page featuring of this article, guys. Thumbs up! :) —Lowellian (reply) 21:59, 5 June 2012 (UTC)

I'm glad it's appreciated. It's been hard work getting it there and a rough ride once it was there but it's worth it in the end. There are some other articles about, or with references to past transits on DYK today too, one there already and two more due later today. Richerman (talk) 22:37, 5 June 2012 (UTC)

Horrock's measure of an AU

The article states that Horrock used his single measurement to estimate the distance to the Sun. If this is in fact possible then a brief explanation of how would be in order, otherwise the claim should be removed. Tuntable (talk) 03:02, 6 June 2012 (UTC)

The issue is discussed in the main article, see Transit of Venus, 1639#Results (and there was a recent discussion on its talk page). As mentioned in the main article, Horrocks arrived at his conclusion from a measurement of the angular diameter of Venus applied to an incorrect assumption. The wording in the article here includes "make an estimate" which is a reasonable summary of the situation: the conclusion involved an incorrect assumption about the diameters of the planets, but was an "estimate". Johnuniq (talk) 03:13, 6 June 2012 (UTC)

The lead images are a mess

I think the lead image as a double image with a big gap to one side looks ugly and I would much prefer to see it with just one really eyecatching image, possibly the one that's now at the top. Failing that a proper montage that someone has taken some time to put together, but certainly not two images jammed together like those are. What do others think? Richerman (talk) 16:45, 7 June 2012 (UTC)

I see it as problematic to include a Solar Dynamics Observatory image as the top image. These pictures are very good, but they are not taken from "Earth". There must be many good images taken from Earth-based observatories to use in this place. A transit is the allignment of planetary bodies against the solar disk, so using spacecraft somewhat defeats the spirit of the endeavor. SkyMachine ⁽⁺⁺⁾ 21:23, 7 June 2012 (UTC)

File:Silhouette of Venus 1769.jpg

• "Silhouette_of_Venus_1769.jpg" was removed from Transit of Venus and Venus.
• "Venus_Drawing.jpg" was removed from 1769 Transit of Venus observed from Tahiti and Charles Green (astronomer) and Black drop effect.

I have asked at commons:User talk:Fastily#File:Venus Drawing.jpg about the deletion of this image, and have mentioned this at User talk:İnfoCan#File:Silhouette of Venus 1769.jpg (who nominated the Silhouette file for deletion). I assume such an historic image should be in at least one article here? This mirror has the old image. Johnuniq (talk) 07:42, 24 July 2012 (UTC)

Fastily has restored the second image (File:Venus Drawing.jpg), and I have put that image back into the above articles, so there is probably nothing more to do. Johnuniq (talk) 09:06, 24 July 2012 (UTC)

Agree. All is fine. --İnfoCan (talk) 13:36, 24 July 2012 (UTC)

Thanks for the new image. I got a bit panicked because I anticipated a long delay before the image was restored, but it happened very quickly. Johnuniq (talk) 23:13, 24 July 2012 (UTC)

Suitable images?

Wikimedia received a communication offering some images related to the transit of Venus.

I see that the article is a featured article, and has some fine images already. I do not know if the images being offered would be useful additions to the article.

The images can be found here

If they are suitable, I can take care of the processing of the permission statement, and can upload them as well.--SPhilbrick(Talk) 14:32, 26 April 2013 (UTC)

First scientific observation?

This article places the first "scientific" observation in the 17th Century, but the article on the Sun notes that "From an observation of a transit of Venus in 1032, the Persian astronomer and polymath Avicenna..."

What makes that one not sufficiently scientific?

--23.119.204.117 (talk) 14:47, 22 August 2016 (UTC)

The 17th century transit was definitely the first transit that was predicted, plotted, measured and used to make an estimation of the size of the Solar system. It's hard to get that the significance of all that across in a simple statement so the word 'scientific' was used. I don't know about the Avicenna observation but presumably he just saw the transit, recognised it was Venus and made a deduction from that. If you can think of better wording perhaps you could suggest something. Richerman (talk) 15:50, 22 August 2016 (UTC)

Ah, from reading the Avicenna article "He claimed to have observed Venus as a spot on the Sun. This is possible, as there was a transit on May 24, 1032, but Avicenna did not give the date of his observation, and modern scholars have questioned whether he could have observed the transit from his location at that time; he may have mistaken a sunspot for Venus. He used his transit observation to help establish that Venus was, at least sometimes, below the Sun in Ptolemaic cosmology, i.e. the sphere of Venus comes before the sphere of the Sun when moving out from the Earth in the prevailing geocentric model." So, if he did see a transit at all, it was a chance observation from which he made a simple deduction. Richerman (talk) 16:03, 22 August 2016 (UTC)

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Gregorian and Julian dates

Can anyone clarify whether this article gives the dates for the Transits of Venus in the 17th and 18th centuries in Gregorian or Julian dates? I am trying to work this out and am not sure now. Carcharoth (talk) 17:26, 18 October 2019 (UTC)

I'm not sure what the problem is. For the 1639 observation both Julian and Gregorian dates are given. For the 1677 transit the old style (Julian) date is given (it's linked to O.S.) and the 1761 and 1769 transits no dates are given in the article but they would be Gregorian as England had adopted the Gregorian calendar in 1752. Richerman (talk) 19:02, 18 October 2019 (UTC)

Thanks for the reply. That is partly my fault for not reading the article closely enough (I searched for 'Gregorian' and got the footnote). Searching on 'Julian' and 'O.S.' gets the other relevant text on this. I do think it would be useful to have actual dates for the 1761 and 1769 transits, as while the 1769 transit of Venus observed from Tahiti article goes into more detail (giving the date as 3 June 1769) and the transit date for 1761 is given as 26 May 1761 in this article (in the caption to the Lomonosov observations image from St Petersburg), it does need to be made clear which calendar is being used here. My question, for what it is worth, came from some research I was doing into the image shown here. That is a collection of diagrams published in London in 1748 (before the adoption of the Gregorian calendar in 1752) and titled "The geography of the great solar eclipse of July 14 MDCCXLVIII" (the date here is 14 July 1748 O.S. referring to the annular solar eclipse of 25 July 1748 in Gregorian date). In the bottom right-hand corner are depictions of the Transits of Venus in 1761 and 1769. The date for the 1769 eclipse is given as 3 June 1769 "in the evening" and "from Dr Halley's Tables for London" - the times there are, I think, apparent solar time. I suspected that that was a Julian date, but was not sure (and it appears to actually be a Gregorian date). Having looked into this a bit more, I see that the Gregorian dates are given here as: 6 June 1761 and 3-4 June 1796. This is consistent with the 26 May 1761 date in St Petersburg being the Julian date. For 1769, the Julian date was 23 May 1769. (Both the Julian and Gregorian dates for the 1769 transit can be seen on this catalogue page referring to the observations published by Nevil Maskelyne and Christian Mayer). It does mean that those publishing that document in 1748 (which is what confused me) were either using a mix of Gregorian and Julian dates (the solar eclipse of 1 April 1764 is given in Gregorian dates) or this is a later and revised state of that document, published closer to or after 1752. Getting back to the Venus transit dates, Richerman, what is the best way to add the 1761 and 1769 dates to the article in both styles? (I made these edits for now). Carcharoth (talk) 11:27, 21 October 2019 (UTC)

The edits look fine to me. If anyone thinks there is a better way to do it I'm sure they'll change it. Richerman (talk) 14:45, 22 October 2019 (UTC)

FA criteria concerns

This one's got a lot of uncited text and there's very WP:UNDUE weight of details given to the 18th-century ones, including big chunks of detail about random unsuccessful attempts to view it. This one needs a lot of work to get back to the current FA criteria. Hog Farm _Talk 16:25, 5 February 2021 (UTC)

On Mars

Transit of Venus isn't exclusively visible from Earth. It's also visible from Mars. So isn't it better to have a section or a separate article for Mars too? Also, look at Transit of Mercury from Mars. Aminabzz (talk) 22:16, 12 December 2023 (UTC)

Citations

Amongst other things, I will be working on checking and amending the references for this article over the next few weeks, so as to get it to GA. Amitchell125 (talk) 17:11, 7 March 2024 (UTC)

Near simultaneous transit with Mercury

In the future transits section, only the next occurrence of a simultaneous transit of both Mercury and Venus is listed, however, on 13425-Sept-17 there will be a near-simultaneous transit. Does this not merit a mention as well? Additionally (and perhaps more importantly), the source provided does not go beyond 2300 CE for Mercury, which is quite short from both the simultaneous and near-simultaneous transits with Mercury as viewed from Earth. Paculino (talk) 17:25, 16 September 2024 (UTC)