Talk:Venus (planet)

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Venus (planet) is a featured article, which means it has been identified as one of the best articles produced by the Wikipedia community. If you see a way this page can be updated or improved without compromising previous work, feel free to contribute.

"Venus has slow retrograde rotation, meaning it rotates from east to west instead of west to east as all other known planets in the solar system do" -- not true; Uranus and Pluto both rotate retrograde, Uranus with an axial tilt of 97 degrees and Pluto with almost 120 deg. I propose fixing this. --Phil Karn

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I updated the irradiance figures to correspond to those found in the table in a NASA publication (http://media.nasaexplores.com/lessons/03-053/9-12_2.pdf). These seem to make more logical sense; if Venus is twice as far from the Sun than Mercury is, then it should only receive 25% the solar irradiance. The NASA numbers correspond nicely. (I also had to change the irradiance given for Mercury, which makes me wonder where the numbers originally came from.) --Bkell 08:01, 4 Mar 2004 (UTC)

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I was wondering the same thing, and I changed that 75% figure to 25% since it was an obvious error. But I didn't have better irradiance figures, so I'm glad you found them. I note that Mercury has a very eccentric orbit, so its irradiance figure will vary quite a bit. --Phil Karn

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Is revolution period same as the planet's sidereal period? It seems to be, and if it really is, the table text should be more precise.

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Given all other measurements being SI, perhaps the "four miles an hour" reference should be converted to km? I don't have the back of an envelope handy to figure whether I should round it to six or seven km/h.

Could the creator of the page send me some links about how to write html to my email dracmandx@aol.com, cause i suck but want to get better

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However, due to the high density of the atmosphere at Venus' surface, even such slow winds exert a significant amount of force against obstructions.

This line is irrelevant to the atmosphere of Venus. Unless you want to describe the consequences of wind-surface interactions then it's just hanging there.Chris Lee 12:03 UTC, 03 Nov 2004

on surface the temperature is never below 400°C.

Most of the paragraph is lax in accuracy, but this is a very broad statement. A simple calculation will show that Maxwell's peak could have a temperature of 350°C, if you use 464°C as the mean surface temperature.

Contents

1 Picture 2 Orbital characteristics 3 Transit picture 4 Cultural references vs. Venus in fiction 5 Astrology 6 Life 7 "Recent" confusion 8 Brightest point of light? 9 Meteor craters 10 Image 11 Athmospheric pressure 12 Page move 13 Appearance

Picture

I think the two planet pictures should be switched, since the RADAR picture is not easy to understand and looks very different from the usual pictures of Venus. Awolf002 23:24, 23 Sep 2004 (UTC)

I agree, and was going to suggest the same thing myself~; the RADAR image is not a picture of what Venus would look like to the naked eye and is thus misleading. The Singing Badger 00:13, 24 Sep 2004 (UTC)

Orbital characteristics

No offence intended, but the recent edits (http://en.wikipedia.org/w/wiki.phtml?title=Venus_%28planet%29&diff=7201323&oldid=7189430) by The Singing Badger were a bit misguided in my opinion, so I have mostly reverted them. Hoping to avert an edit war, here are my reasons:

• The section name "Getting to Venus" is more accurate than "Landing on Venus" because the issues discussed:
  • have no bearing on actual atmospheric entry and touchdown
  • are relevant whether or not one wants to actually touch down on the surface of Venus, or merely orbit it (or even fly by)
• I think starting out by mentioning where Venus' orbit is located fits perfectly in a section on how to get there. Separating it into its own tiny single-paragraph section serves no purose to my mind.
• There is no article called gravitational well, and it's not clear to me that there should be such an article, so I decided to use italics instead.
• Falling toward Venus does not "create" potential energy. In fact, you lose potential energy when you fall. My original phrasing was that the fall toward Venus represents a lot of potential energy that must be dissipated, and I think that's a more accurate statement.
• I'll acquiesce on the addition of the word "thus", and the changing of "something" to "rather".  :-)

Please let me know if you think I have made the article worse. --P3d0 21:39, Nov 8, 2004 (UTC)

No worries, I don't do edit wars. :) I know nothing about orbital dynamics, by the way, I'm just interested in clarity for the reader.

• My initial reason for editing was that it seemed odd to put this useful addition between the section on the first flybys and the section on the first landings. Because of this placing, I assumed your reason was that the information is specifically pertinent to landing on Venus (and indeed you mentioned soft landings by name). If you're in fact talking about travel to Venus in general, we can simply move the whole section to the beginning of the 'Observation by spacecraft' section where it makes more sense.
• I moved the orbit section simply because the section on the circularity of the planet's orbit is useful info that shouldn't be buried in a section on space travel. I admit it did look crap in a section on its own, though; maybe it belongs in the overview or something?
• If 'gravitational well' is not an official scientific term it should be in quotation marks, not italics; if it is, it shouldn't have any formatting around it.
• On everything else, I apologise for trying to correct things I know nothing about...!

I'll do some of these edits and if you disagree with them, by all means change again. The Singing Badger 22:17, 8 Nov 2004 (UTC)

I like what you've done. Looks great! --P3d0 03:49, Nov 9, 2004 (UTC)

Having done some math, it turns out it's not all that hard to get to Venus, so I have moved that "driving off a cliff" text to Mercury (planet), which requires three times the rocket fuel. --P3d0 17:49, Nov 9, 2004 (UTC)

Sorry, I stetted that paragraph it before I read this. (Of course, it is not that hard to get to Venus,

Not so obvious, compare Mercury_(planet)#Getting_to_Mercury.--Patrick 23:55, Nov 9, 2004 (UTC)

Ah - had forgotten angular momentum. Nice section. I coudn't help tweaking it a little. -- ALoan (Talk) 11:18, 10 Nov 2004 (UTC)

the problem is staying there!) How hard is it from an spacecraft from Earth to enter an orbit around / land softly on Venus? Would it be better to compare it to, say, skateboarding down a hill and trying to stop at the bottom, rather than driving off a cliff? -- ALoan (Talk) 18:39, 9 Nov 2004 (UTC)

I calculate the Hohmann transfer requires a delta-v of 5 km/s for Venus and 15 km/s for Mercury, neglecting Earth's and Venus' own gravity. Escape (which current technology has never achieved without a gravitational slingshot) requires 12 km/s. If you are interested, I can do a real calculation including escape from Earth and capture by Venus/Mercury. The overall effect would be to make the delta-vs larger and more similar. In fact, according to this very cool chart (http://www.pma.caltech.edu/~chirata/deltav.html), the planetary gravity would add about 6.4 km/s to all these numbers, so (without double-checking) that gives 11.4 to Venus, 21.4 to Mercury, and 18.4 to escape the sun. --P3d0 19:07, Nov 9, 2004 (UTC)

Interesting - so Mercury is more difficult to get to than escaping the Solar System! An interesting factoid for Mercury (planet), no? And Venus is about 33-50% as hard as Mercury. Are these points worth mentioning somewhere? -- ALoan (Talk) 20:34, 9 Nov 2004 (UTC)

I can do the numbers more rigorously if you like, and then we can decide how to phrase them. (Remind me if I forget!  :-) --P3d0 19:55, Nov 11, 2004 (UTC)

Transit picture

Does anybody have a "real" (and GFDL) picture of the 2004 transit? The current picture is from a simulation! Awolf002 16:28, 10 Nov 2004 (UTC)

Are the ones on Transit of Venus or Transit of Venus, 2004 appropriate? -- ALoan (Talk) 20:11, 10 Nov 2004 (UTC)

Right! Those are good. I will pick one and change it. Awolf002 14:49, 12 Nov 2004 (UTC)

Cultural references vs. Venus in fiction

I think "Venus in fiction" is too narrow. The section should include other cultural expressions, and references to other cultures than the Anglo-Saxon/Western. See discussion on Wikipedia:Featured_article_candidates. — David Remahl 16:52, 11 Nov 2004 (UTC)

I don't think anyone would disagree with you on that. It needs to be written though. When that's done, 'Venus in fiction' could simply be a subheading within a larger section on cultural references. The Singing Badger 18:27, 11 Nov 2004 (UTC)

True. While I'm not really qualified to, I'll make an attempt at reducing the bias in the article. Someone more knowledgeable will no doubt clean it up in the future. — David Remahl 23:35, 12 Nov 2004 (UTC)

Astrology

Shouldn't there be a page about how the planet Venus is interpreted in different schools of astrology?

You mean "page", right? Not "section in this page"? This article is geared toward the physical side of the planet, not it's mythological one. I think astrology would not fit in this page. Also, look at the dab page Venus. Awolf002 15:21, 2 Dec 2004 (UTC)

Life

I know at least one research team has suggested microbes might live in the upper atmosphere of Venus. Some one who knows more about this might add it. Marskell 10:35, 17 Mar 2005 (UTC)

"Recent" confusion

The radically different connotations of the word "recent" in the third paragraph of the "Suface features" section are confusing. I assume, but cannot know from this article, that "recently-solidified basalt lava" implies "several hundred million years" ago, based on the later text in the paragraph. I'm fairly certain that the "recent results from... Magellan" are only a few years old at most, based on the lack of Pleistocene-era space probes. (The link helps, too. ☺) Unfortunately, my beleaguered brain is failing to come up with a concise way of reducing the time-scale whiplash. Could someone else give it a go? — Jeff Q (talk) 02:45, 28 Mar 2005 (UTC)

Perhaps "geologically recent" should be OK in the first case. Geo- here is confusing a bit, but searching with Google I found it used concerning Mars [1] (http://uanews.opi.arizona.edu/cgi-bin/WebObjects/UANews.woa/wa/SRStoryDetails?ArticleID=3817). Cmapm 18:57, 30 Mar 2005 (UTC)

This is alreday fixed by somebody, however. Cmapm 19:01, 30 Mar 2005 (UTC)

Brightest point of light?

Regarding the following:

It is sometimes referred to as the "Morning Star" or the "Evening Star", and when it appears it is by far the brightest point of light in the sky.

What about when the sun and/or moon are out at the same time? Venus is the third brightest object in the sky, unless one is being very specific about points of light. -- Gyrofrog (talk) 16:26, 28 Mar 2005 (UTC)

I think the sentence means that Venus is the brightest star-like object in the sky. Maybe slightly misleading, but in the next paragraph it is described as third brightest object in the sky. Should they be combined to avoid repetition?--Jyril 17:10, Mar 28, 2005 (UTC)

I've tried to clarify the statement a bit, although it might be more sensible just to omit the fact that it's the brightest point source and just stick with mentioning that it's the third brightest overall. Worldtraveller 22:08, 28 Mar 2005 (UTC)

Meteor craters

"Owing to Venus's thick atmosphere, which causes meteors to decelerate as they fall toward the surface, no impact crater smaller than about 3.2 km in diameter can form."

if meteors are slowed, shouldnt the craters be smaller ie "no impact crater greater than..."?

I've tried to make that bit of the article a bit clearer on this point. The situation is that the smaller meteors burn up completely, the intermediate ones might reach the ground but are slowed to such low speeds that they don't form craters. Only the largest can reach the ground and still have enough energy to form a crater, and this results in a minimum size of crater that can be formed. This page (http://www.astro.uiuc.edu/classes/archive/astr100/s03_lect3/discussion.html) contains a good explanation of the general principle. Worldtraveller 22:08, 28 Mar 2005 (UTC)

Image

Following precident of other planet articles shouldn't the visible light image be the one at the top of the page in the table?--Deglr6328 05:51, 31 Mar 2005 (UTC)

I agree. See for example the german Venus article de:Venus (Planet). I think the best visible light picture of Venus was the one taken by Galileo probe, which is already in the "Observation by spacecraft" subsection --Bricktop 03:39, 14 Apr 2005 (UTC)

Athmospheric pressure

I was wondering: How comes that the pressure of Venus's atmosphere is so much higher than Earth's although both planets have roughly the same mass and should hence be able to retain the same amount of gas in their gravity well? Anybody happens to know? TIA. Simon A. 16:23, 31 Mar 2005 (UTC)

The Earth has little carbon dioxide in its atmosphere but far more locked in carbonate rocks. There's enough carbon dioxide in the Earth's rocks to allow a Venus-like density if it were released. More significantly, the Earth's water has a huge volume of material (water, of course) that would become atmosphere if the Earth were to be warmed to Venus-like temperatures. Most theories hold that as the sun expands to a gas giant toward the end of its life, the Earth will slowly be warmed to temperatures around 60°C, at which point a runaway greenhouse effect will take effect, and then temperatures will skyrocket. An increasing load of water vapor will itself add density to the atmosphere (that itself raising the temperature) and accelerate the greenhouse effect, until at roughly 305°C, the critical point of water, the greenhouse effect from water vapor will no longer cause further heating. Any increased temperatures will result from the further expansion of the sun, and at another point, carbon dioxide will be released from carbonate rocks.

With an even higher pressure, the Earth would become even hotter than Venus even if the upper atmosphere clouds enough to prevent any sunlight from reaching the Earth's surface. But the Earth's seething surface will be anything but dark; its rocks will radiate heat which will likewise be prevented from escaping through the same clouds that prevent the entry of all but the dimmest sunlight.

Don't be unduly scared. This won't happen for hundreds of millions of years. So far, the Earth has a relatively thin atmosphere, much unlike that of Venus, that isn't very good at holding onto heat. We still have real winters from about 35° north and south poleward, and real nights everywhere. We are safe so far from the runaway greenhouse effect, and the carbon dioxide that would make the Earth a Hellish place is safely locked away.

Venus, in contrast, is too hot to have any carbonate rocks. It's also too hot to hold water vapor. An atmosphere as crushing as that of Venus is hot in its own right. The perfect gas law (PV=nRT) implies that temperature is proportional to pressure, and Venus has enough atmospheric pressure to be exceedingly hot in its own right.--66.231.38.97 01:20, 15 Jun 2005 (UTC)

Page move

This page was moved from Venus (planet) to Venus. Is this being done for all of the planets? Did I miss the discussion? Is a reader more likely to be looking for the planet or the god? -- ALoan (Talk) 09:45, 14 Apr 2005 (UTC)

Yes, this is surprising! I think this should be reverted and then discussed! Awolf002 13:41, 14 Apr 2005 (UTC)

Appearance

This new table does not fit into this article at all. I will remove it, if no objections are made. Awolf002 12:37, 17 Jun 2005 (UTC)