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Revision as of 23:39, 15 September 2007

	Mercury (planet)/Archive 1 is a featured article; it (or a previous version of it) has been identified as one of the best articles produced by the Misplaced Pages community. Even so, if you can update or improve it, please do so.
	Mercury (planet)/Archive 1 is part of the Solar System series, a featured topic. This is identified as among the best series of articles produced by the Misplaced Pages community. If you can update or improve it, please do so.
	This article appeared on Misplaced Pages's Main Page as Today's featured article on August 25, 2006.
Article milestones Date Process Result November 28, 2005 Good article nominee Listed December 16, 2005 Peer review Reviewed May 3, 2006 Featured article candidate Promoted October 15, 2006 Featured topic candidate Promoted Current status: Featured article

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This page has a lot of useful infomation for a 13 year old girl like me and i am doing reasearch on Mercury and I got most of my project done on this website or that page. Thanks again

amanda 13 from albany NY

No problem, Amanda. This is the whole reason why we're working on Misplaced Pages in the first place, and comments like this let us know that it's all worthwhile. :) Bryan

• Amanda's comment prompted me to come out and become an user. Twelve-year-old Dralwik 01:53, 11 Nov 2004 (UTC)

Yes, soon the school industry will be left in shambles! BWAHAHAHAHAH! Susan Mason

It will with all the pupils using websites like this! --06cat 08:43, 6 February 2007 (UTC)

I think this has helped me with my Solar System research 0_o; Thanks for, erm, existing, Misplaced Pages! <3 ~ Paratroopa Platoon #174

Why is this page so confussing? I mean I am doing a science project and I dont understand this website at all. Well anyways buh-bii!!<> ~ Megan LeBlanc 4-27-07

I use Misplaced Pages for most of my research, and when I need more, I can look at the external links. I'm 13 btw. 68.4.212.158 05:39, 25 August 2006 (UTC)

Pizza, you added "A third theory argues that the outer parts of Mercury were "eroded" by the solar wind." as one of the explanations that have been presented for why Mercury has such a big core. How is this different from the theory mentioned immediately before it, in which Mercury's crust was vaporized and blown away by solar wind? Did it blow Mercury's crust away while it was still solid instead, in which case, how were such hellaciously strong solar winds possible? I think this could use more detail, or some kind of reference, or something. Bryan 02:15 8 Jul 2003 (UTC)

Yes, the third theory is similar to the second -- except, the argument is not so much that the heat of the solar nebula vaporized the crust and it was then blown away; but rather, that the impact of particles upon the mantle (rather than the crust - which was not solid, but also not vaporized) stripped the outer layers. The two theories vary as to the timescale; the second one involves a longer more gradual process. Pizza Puzzle

Oh, and also, I just removed this paragraph:

Unlike Earth, Mercury does not have synchronous rotation around Sol. In addition, gravitational force have created tidal bulges upon the planetary surface.

because Earth doesn't have synchronous rotation, and all planets have tidal bulges so I don't see what's special about Mercury's. Bryan

Well this text here states: "The Sun created a significant tidal bulge on Mercury...", I suppose it was wrong to infer that Earth had a synchronous rotation. Pizza Puzzle

According to the table in Earth its temperature varies from 184K to 333K. The way I reckon that makes 149K between them, not 11K. Maybe its just a misunderstanding on my part as to what that 11K refers to; but it probably could be expressed more clearly.

I suspect that this is just the average temperature variation between day and night at any given point, not the global extremes. Bryan

Bryan is correct. Pizza Puzzle

OK, anonymous editor comes along and adds in the surface gravity compared to Earth, which is nice. But also "corrected" the straightforward surface gravity from 2.78 m/s² to 0.926 m/s². Fits with the compared-to-Earth number of 0.0945, at least. But meanwhile, using the numbers in there for the mass and diameter, I get a surface gravity of 3.70 m/s². Looking back through the history, it's been 2.78 m/s² since the page first got a surface gravity. What gives?!? -- John Owens (talk) 23:25, Mar 26, 2004 (UTC)

Checking his/her other edits, some of them look OK, some of them don't. Phobos (moon) seems not right, but Deimos (moon) looks good, Iapetus (moon), Uranus (planet), and Venus (planet) seem OK. Will add more here as I check them out. -- John Owens (talk) 23:39, Mar 26, 2004 (UTC)

All the other edits from that IP (User:207.168.80.40 | contributions) look OK. It's just Mercury here and Phobos that aren't right, but I don't know if I can even agree with the prior 2.78 m/s² figure here. -- John Owens (talk) 00:00, Mar 27, 2004 (UTC)

Every reference I can find lists the surface gravity of Mercury as 38% of Earth's. Which would make it 3.71 ms-2. -- DrBob 00:12, 27 Mar 2004 (UTC)

OK, I went ahead and made the changes here and at Phobos. Though I'm a bit conflicted about Phobos, since it depends on where you measure its diameter, but the numbers that were there weren't even between the max and min diameter gravities. I used the min diameter, max gravity there. -- John Owens (talk) 00:35, Mar 28, 2004 (UTC)

Supernova survival

What is this?

Furthermore, in the (unlikely) event of a nearby star going supernova, the large iron core of Mercury could protect the colonists in almost half of the possible directions; if this happened, the colonists at Mercury's pole might well be the only human survivors in our Solar System.

Does anyone have a source for this, or is it speculation? --P3d0 20:25, Nov 11, 2004 (UTC)

Sounds like speculation. A supernova would need to be really near to us to produce enough radiation that a planetary core is necessary for shielding it, and I don't think any candidate stars are that close. Furthermore, the initial pulse of strong radiation would not last very long so even fast-rotating planets like Earth would have significant portions of its surface shielded just as well. I don't think it's a problem. I found this page with some information about radiation levels from nearby supernovae: Bryan 07:03, 12 Nov 2004 (UTC)

Ok, I chopped it. For posterity, the version with the supernova speculation is here.

Human colonisation

Why does the Mercury article talk about Human colonisation when the other planetary articles do not?

Probably because the colonisation of Mercury provides interesting chalanges unique in our solar system. Armaced 15:57, 6 Apr 2005 (UTC)

^__^

Also because Mercury plays a pivotal role in some alternate interstellar propulsion schemes --such as those where high-power lasers are used to push solar sails. Basing those on Mercury makes some sense.

Urhixidur 2005 July 2 16:25 (UTC)

Potential for human colonization

Would it be possible to cite a source or external reference for the information about the potential for human colonization which is included in this article (something like a NASA study, a paper in a scientific journal, or a web site)? --DannyZ 05:45, 22 May 2005 (UTC)

Ephemeris of Mercury

Why not to put an ephemeris for mercury in the Misplaced Pages? The following ephemeris runs from January 1st, 2005 to January 1st, 2015. Right ascension and declination are in actual equinox. First column is right ascension, second declination, third elongation to sun. The ephemeris is valid for 0h UTC

A prime reason why not is that this list of data is huge. It's ~160 kilobytes of raw numbers of very little interest to the average reader of this sort of article. Perhaps someplace like Wikibooks or Wikisource might be more appropriate? Bryan 04:26, 20 Jun 2005 (UTC)

I just deleted the list entirely, it was wasting a huge amount of space in this talk page. It's available in the article's history still. Bryan 2 July 2005 19:16 (UTC)

Mercurian Day?

On the Potential For Human Colonization subject it was written that a base on Mercury could use a heat sink to store up heat for the night. Does the author realize a mercurian day is about 60 days long? Or was the section talking about Earth's Moon still? If it was, it should be made clearer.

(PS. I'm kinda new to wikipedia, correct me if I'm doing something wrong here)

From the article-

"Due to the lack of atmosphere to conduct heat, a thermal radiator hidden in the shadow of a sun screen would be able to reject heat into space even at the height of the Mercurian day. Alternatively, the base could use a heat sink during the day to store up heat for disposal during the night. Protecting mobile vehicles or robots against solar heating might prove much more difficult, however, which may limit the amount of surface activity that could be performed during the day."

(Personally, I'd make a mobile base that would just crawl along the surface at about 4 mph to stay in the nice twilight.)

Mercury's got no atmosphere so the base would only have to deal with radiant heat from above and conducted heat coming through the rock below. Radiant heat can be largely dealt with using reflective sunshades and conduction through rock isn't particularly fast, so there might actually not be a huge amount of extra heat to deal with - a large heat sink might be quite adequate even during a 60 day long day. I haven't run any numbers, though, I'm just suggesting that it may not be as outlandish as it seems. A base under similar conditions with an atmosphere would get more severely cooked because the atmosphere would circulate past it, enhancing heat transfer.

Oh, and you're doing nothing wrong - this is exactly the sort of thing these talk pages are for. :) Bryan 2 July 2005 19:24 (UTC)

Thanks for responding, I do wonder if a heat sink would be able to dissipate enough heat away in an near perfect vacuum. I've heard the shuttle will overheat if the bay doors don't open in orbit. By the way, have you seen Mercury recently? Yesterday was the first time I've seen it. It's just above the horizon just after it gets dark. The special treat is Venus, which is only 1 degree away. But you may already have heard about that. And by the way, lets not try to land on Venus any time soon- sulfuric acid rain, 400 degrees in the shade, etc.

Page move

I disagree with the page move to just Mercury instead of Mercury (planet). There was no discussion here on the talk page, and (more importantly) Mercury is unique among planets in that the word "mercury" has another meaning that is arguably just as common: that of the chemical element. (Well, not really unique I guess: "earth" can mean dirt, and "Pluto" might be a cartoon dog.) --P3d0 01:16, August 14, 2005 (UTC)

I agree completely - the move should not have been done at all. I'll take a look and reverse the move if need be. -- Chuq 01:53, 14 August 2005 (UTC)

The pages have been moved back. I just noticed the user who made the change (User:Kitch) has done the same to Pluto, Saturn and Neptune.. I may leave these for someone else to look at! -- Chuq 09:42, 14 August 2005 (UTC)

Cut sections

I've just re-written quite a lot of the article for style and accuracy. I've removed two sections, on the potential for space colonisation and data about elongations; the first, because it seems to be pure speculation, and the second because it is an enormous block of table which seems out of place in an encyclopaedia article. Others might disagree with my removal; for convenience I've copied them both here:

Potential for human colonization

A crater at the North or South pole of Mercury might prove to be one of the best locations for an off-Earth colony, as the temperature would remain almost constant (at around minus 200 degrees Celsius). This is because Mercury has negligible axial tilt and essentially no atmosphere to carry heat from its sunlit portion. It would thus always be dark at the bottom of a crater at the planet's pole, even a shallow one. Human activities could warm the colony to a comfortable temperature, and the low ambient temperature would make waste heat disposal easier than most locations off Earth.

A base elsewhere would have to be able to deal with many weeks of continuous intense solar heating followed by many weeks without any external heating at all. This would not necessarily be as difficult as it may first seem. Facilities could be buried under several meters of loose-packed regolith, which in a vacuum would serve as effective thermal insulation as well as a radiation shield. Similar approaches have been proposed for bases on Earth's Moon, which has two-week-long days followed by two-week-long nights. Due to the lack of atmosphere to conduct heat, a thermal radiator hidden in the shadow of a sun screen would be able to reject heat into space even at the height of the Mercurian day. Alternatively, the base could use a heat sink during the day to store up heat for disposal during the night. Protecting mobile vehicles or robots against solar heating might prove much more difficult, however, which may limit the amount of surface activity that could be performed during the day.

Appearance

Worldtraveller 23:13, 5 September 2005 (UTC)

declination

Why does the table give: Declination 61.45° I thought that declination of planets is variable. Cartes du Ciel says that mercury's declination is now +03°41'04.1?

I'm also confused about that. I guess the north pole of mercury points to that position. 84.169.247.228 19:23, 17 March 2007 (UTC)

Yes, that's what it was. The infobox has been fixed to reflect this better now. Urhixidur 04:08, 19 March 2007 (UTC)

Exploration of Mercury

"The approaching spacecraft cannot use aerobraking to help enter orbit around Mercury since it has no atmosphere and must rely on rocket boosters." MESSENGER "will explore the planet's atmosphere, composition and structure." How can it explore the planet's atmosphere if it has none? Teply 04:26, 29 November 2005 (UTC)

If you look at the infobox (at the top right of the article) you will see that the atmosphere is listed as "trace" - that is, there is an atmosphere of sorts (most likely, I guess, outgassing from the baked sunwards side, and the odd stray atom floating around on the dark side) but it is very tenuous and certainly not sufficient to give any appreciable friction for aerobraking. In fact, it is so rarified that the atoms in it may be so far apart that they never collide (see exosphere).

It is not too different to the Moon . But the atmosphere that is present, such that it is, is worth exploring. -- ALoan (Talk) 12:22, 29 November 2005 (UTC)

Dear NASA

Dear NASA,

Why not send weather satellites to Mercury? Then we could put them on TV, for a Mercury Weather Channel akin to the current (Earth) Weather Channel. I'm sure lots of people would be interested to see up-to-the-minute pictures and video of Mercury. oneismany 11:54, 29 November 2005 (UTC)

Proposed move

The following discussion is an archived debate of the proposal. Please do not modify it. Subsequent comments should be made in a new section on the talk page. No further edits should be made to this section.

The result of the debate was: consensus was to not move—jiy (talk) 19:05, 8 January 2006 (UTC)

• Oppose. The dis-ambiguation page has 2 primary meanings, the planet and the element. Georgia guy 02:19, 2 December 2005 (UTC)
• Oppose. The element is at least as important as the planet, and even the god might be a reason to keep a disambig page at Mercury. Kusma (talk) 02:56, 2 December 2005 (UTC)
• Oppose. Google search for mercury returns the automobile company! :-) Seriously, I don't see the strong case for the planet over any other meaning. Tedernst | Talk 04:16, 2 December 2005 (UTC)
• OPPOSE, Hg is by far the more prevalent meaning. 132.205.44.134 23:40, 2 December 2005 (UTC)
• Oppose. Hg is more frequently linked and the god is also primary. Jonathunder 03:12, 3 December 2005 (UTC)
• Oppose. The planet and the element are neck-and-neck. Urhixidur 04:54, 3 December 2005 (UTC)
• Oppose. As per above. Marco79 17:19, 3 December 2005 (UTC)
• Oppose, for the reasons explained above.--Jyril 18:07, 3 December 2005 (UTC)

The above discussion is preserved as an archive of the debate. Please do not modify it. Subsequent comments should be made in a new section on this talk page. No further edits should be made to this section.

Wrong duration of bombardment

CalRis: In the section Surface Features the following is said:"...it was heavily bombarded by comets and asteroids for a period of about 8000 million years." AFIK, our solar system is only about 4500 million years old. Shouldn't it rather say 800 million years or something like that? Bye.

Inconsistency

 "Mercury (planet)" applies the phrases "Morning Star " and "Evening Star" to Mercury. The separate articles

"Morning Star" and the like refer to Venus. 81.132.55.206 15:01, 1 February 2006 (UTC)

Structure

I've just been looking at the German version of this article, and I think the way theirs is laid out is better than this is at the moment. It allows coverage of all significant aspects of the planet in a very clear and organised way. Below is their TOC - what would anyone think about rearranging our article along these lines? Worldtraveller 00:48, 11 March 2006 (UTC)

1. Structure

1.1 Atmosphere

1.2 Surface

1.2.1 Possibility of ice

1.2.1.1 Indications in the detail

1.2.1.2 Possible origin

1.3 Internal structure: core, mantle and crust

1.3.1 Cause of high iron content

1.4 Magnetosphaere

1.5 Geological development stages

2 Orbit and rotation

2.1 Advance of perihelion

2.2 Orbital resonance

3 Research

3.1 Ground-based research

3.2 Research with space probes

3.2.1 Marine 10

3.2.2 MESSENGER

3.2.3 BepiColombo

4 Observation

4.1 Visibility

5 Cultural history
6 See also
7 Literature
8 Web links

8.1 Video

I took this TOC and put all of our current content into it - see Mercury (planet)/temp. It highlighted some gaps in our coverage which I've started to fill. If no-one objects I'll move what's in the temp page to this page later today. Worldtraveller 11:55, 23 April 2006 (UTC)

I implemented the new structure in the main article. I have to say I think it is much clearer than the previous. It's highlighted some gaps though! Worldtraveller 09:13, 25 April 2006 (UTC)

Chthonian planet?

"Tentative suggestions have been made that Mercury may be a Chthonian planet." Can anyone provide any citation for this? It is also mentioned on the chthonian planet page, no citation there either. Chaos syndrome 17:47, 19 March 2006 (UTC)

I couldn't find any backing for this claim so I removed it when I changed the structure. Worldtraveller 09:13, 25 April 2006 (UTC)

Edits

The section edit boxes all appear at Orbit. Could someone fix that? I don't know how to fix formatting things of that sort, as far as I know those are automatic and I don't have experience dealing with such things. --Keflavich 05:06, 24 April 2006 (UTC)

I don't know if there's anything we can do about that unfortunately. The edit links are placed automatically by MediaWiki and only removing the info box would get them back to the right place, I think. Worldtraveller 09:13, 25 April 2006 (UTC)

Request

The section on cultural understanding is one that needs work. Can anyone add to it? Once it's a decent overview I'm thinking this article is beginning to look like it might be a worthy FA candidate. I'm just adding references and tidying up prose in the rest of the article at the moment. Worldtraveller 10:04, 26 April 2006 (UTC)

I moved this section to a better place and renamed it 'Early astronomers'. The Singing Badger 12:36, 26 April 2006 (UTC)

OK, I like that. Bit of a gap between the greeks and the 17th century though - I'll see what I can find out and if anyone else can add anything that would be great. Worldtraveller 12:51, 26 April 2006 (UTC)

Spelling consistency

I'm editing the article to make all spellings consistently follow American usage. This is because the oldest version of the article used American spellings (kilometer, not kilometre). Angr (talk • contribs) 09:08, 29 April 2006 (UTC)

What colour is Mercury?

The NASA maps of the planet make the surface look brown. Yet I've seen artist's impressions that make the planet grey, like the Moon. Does anyone know which is correct? The Singing Badger 02:11, 2 May 2006 (UTC)

Mercury's Magnitude

 The maximum magnitude of Mercury seems to be -1.9. A standard

magnitude seems to be -0.42. The average magnitude seems to be 0.0. The minimum is about 1.3 or a slightly higher number. The numbers in the article seem to be wrong.

Magnitude

According to Astronomy magazine, Mercury will have an apparent magnitude of -0.9 on June 9, which is half a magnitude brighter than the maximum of -0.42 listed here. That -1.9 seems reasonable, but the -.42 is clearly wrong--Syd Henderson 21:13, 14 May 2006 (UTC).

This page gives the range as roughly -2.0 to 5.5. I've changed the numbers in the article, and investigated the history - the numbers were added in July 2003 and haven't been questioned until now! Thanks for picking up on this long-standing error! Worldtraveller 23:26, 18 May 2006 (UTC)

Here are some others: My Peterson Guide Stars and Planets (2000 Edition) says -2.3 is the maximum magnitude of Mercury, but Kaufman's Universe (1985) and The Guiness Book of Astronomy Facts and Feats (2nd Edition, 1983) both agree on -1.9. The "About -2" is okay.)--Syd Henderson 03:03, 19 May 2006 (UTC)

Distance from the Sun

Shouldn/t Mercury's distance from the Sun appear near the top of the article? I imagine this # is buried in some astro. shorthand in that table, but it should be more plain, no? Sfahey 03:05, 25 May 2006 (UTC)

Advance of perihelion

The explanation given sounds like it is referring to phenomena predicted by special relativity, not general relativity. That is incorrect, as the SR contribution is only about 7"/century, and was already taken into account before Einstein published his explanation based on GR. I don't know an easy way to explain how the anomalous precession derives from GR, or I'd fix this myself. --Mmm 08:21, 16 July 2006 (UTC)

The GR contribution as given in "The Fundamentals of General Relativity" published in 1916 by Einstein can be derived form an effective potential

${\displaystyle V_{eff}(r)=V_{Newton}(r)\left(1+{\frac {l^{2}}{c^{2}r^{2}}}\right)}$

where l is the mass specific angular momentum, c the speed of light, and r the distance to the center of mass. The calculation is purely classical, neglecting any chance in mass. The potential is effective in the sense that the trajectory is calculated as if there would be a potential of that size. But, it depends on the angular momentum, a property of the planet rather than the gravitational field of the Sun.

Moreover, the effective potential causes other chances to the trajectory rather than only an advance of the perihelion.

A pure advance of the perihelion would be decribed as ${\displaystyle r(\varphi )={\frac {p}{1+e\,cos(k\varphi )}},}$

where p,e and k are constants and ${\displaystyle \varphi }$ the angle between the space componentents in cartesian coordinates. Such a trajectory would result from a potential of the form

${\displaystyle V(r)={\frac {\alpha }{r}}+{\frac {\beta }{r^{2}}}}$

84.169.196.154 09:15, 23 March 2007 (UTC)

I believe the SR contribution is indeed about 15"/century. This is the result of the following simulation.

#include <stdio.h>
#include <math.h>

main(){

 int N = 1500000,i;        /* number of iteration steps, counter for time */
 double AE = 1.49598E11;   /* AU average distance Earth to Sun  */
 double c  = 299792458;    /* speed of light                    */
 double e  = 0.0256;       /* eccentricity of orbit             */
 double a  = 0.3871;       /* semi majajor axis                 */
 double pi = 4*atan(1);    /* 3.1415 ..                         */
 double wfak = (180/pi)*3600;  /* convertion to arc seconds     */
 double rx = a*(1-e)*AE;       /* distance mercury sun          */   
 double ry = 0;
 double T = 87.969*(60*60*24); /* siderial period */
 double vx = 0;
 double vy = AE*(2*pi*a)*(1+e)/T;  /* max. orbital speed  */

 double GM=1.32712440018E20;  /* G mass of Sun             */
 double mcc = 1;              /* rest energy               */
 double v;
 double E,m,px,py,p;          /* energy, mass, momentum,  */
 double beta,flag=1;          
 double w0,w1;                /* initial and final position of perihelion  */
 double dt = T/(double)N;     /* interation step - time interval           */
 double r0,r;                 /* distance to sun                           */
 int max = 100*N;
 int count = 0;               /* number of perihelion transits */

  v = sqrt(vx*vx+vy*vy);
  beta = v/c;
  E = mcc/sqrt(1-beta*beta);
  r = sqrt(rx*rx+ry*ry);
  m = E/(c*c);
  py = m * v;
  px = 0;

 for(i=0;i<max;i++){

    rx += vx*dt;
    ry += vy*dt;
    r = sqrt( rx*rx + ry*ry );

    if (r < r0 && i>1) {
        if (flag==1) printf("aphelion %d %f %f\n",i,r,wfak*ry/rx);
        flag=-1;
    }
    if (r > r0 && i>1) {
        if (flag==-1) {
            printf("perihelion %d %f %f\n",i,r,wfak*ry/rx);
            if (count==0) w0 = wfak*ry/rx;
            w1 = wfak*ry/rx;
            count++;
        }
        flag=1;
    }
    r0 = r;
    /* dp = F * dt */
    px -= ((m*GM)/(r*r*r))*rx * dt;
    py -= ((m*GM)/(r*r*r))*ry * dt;
    p = sqrt(px*px+py*py);
    /* E^2 = (m0 c^2)^2 + (pc)^2 */
    E = sqrt(mcc*mcc + (p*c)*(p*c));
    /* E = m c*c */ 
    m = E/(c*c);
    /* v = p/m */
    vx = px/m;
    vy = py/m;
 } 
 printf("\n\nSR contribution /century %f\n",
        (100*86400*364.24)/T*(w1-w0)/(count-1));

}

This result looks quite plausible, since the relative mass dilation

${\displaystyle {\frac {m(v)-m(v=0)}{m(v=0)}}={\frac {1}{\sqrt {1-\left(v/c\right)^{2}}}}-1\approx {\frac {1}{2}}\left(v/c\right)^{2}}$

is even somewhat smaller than the advance of perihelion measured in radians.

It looks unrealistic to measure such small pertubations. At least there are many speculation about all kind of pertubations of the orbit in that order of magnitude, which are not completely understood. 84.169.211.110 08:12, 29 March 2007 (UTC)

But this consideration seems to be wrong, since the mass is m = E/c = (E_kin + E_pot)/c. The total energy of Mercury is (almost) constant, so that there is (almost) no effect. --88.68.120.203 11:50, 31 August 2007 (UTC)

The question is, wether E_pot contributes to the mass of Mercury, the Sun or the Solar System. E_pot is neglectable compared to the rest energy of the Sun, so that in this case the simulation might be correct. --84.59.142.93 09:38, 2 September 2007 (UTC)

Smallest planet?

Now that Pluto's not a planet anymore, Mercury is probably the smallest planet. Discuss.PhoenixSeraph 14:02, 24 August 2006 (UTC)

Not much to discuss. Article's 1st sentence has been changed appropriately.--Planetary 00:25, 25 August 2006 (UTC)

I completely disagree that there is nothing to discuss. "Planet" is part of the English language and not a trademark of the Internation Astronomical Union; regardless of their vote, many people will continue to consider Pluto a planet, myself among them. It is POV to declare Mercury the smallest planet. Nareek 02:00, 25 August 2006 (UTC)

So the NPOV thing to do is make sure the article points out who holds which views. I'll add some further clarification. Bryan 03:04, 25 August 2006 (UTC)

Was it POV to declare Pluto the smallest planet? By your definition of "point of view," yes, because you could just consider whatever you wanted to be a planet. Simply because enough people agree that something is true does not make it true, sir. Go read Nineteen Eighty Four, or if you already have, this time pay attention. Also, the comments about this alternative point of view are innappropriate for this article given that the issue is about Pluto and the planetary redfinition, not Mercuy. Such discussions belong in those articles. Mikeguy 03:13, 25 August 2006 (UTC)

I'm not sure I follow your objection, but it seems to me that discussion of whether Mercury is the smallest planet in the solar system is entirely relevant in the article that's about Mercury. I'm also not saying that it's necessarily "true" that Mercury is the smallest planet. I do, however, say that it's true that it is currently considered by the IAU to be the smallest planet in accordance with their recent change in what they consider to be a planet. Whether you agree with them or not, this is a factual description of their POV. Bryan 03:24, 25 August 2006 (UTC)

The 1984 analogy is hardly apt, unless you believe that a group of mathematicians could get together and declare that 2 and 2 equals 5. Whether Pluto is a planet or not is a matter or semantics, not a matter of reality, just as is the question of whether Europe is a continent or not. If a substantial number of people continue to believe that Pluto is a planet, and I believe they do, Misplaced Pages should reflect this disagreement.

The relevance of this controversy to the question of whether Mercury is the smallest planet or not shouldn't need to be pointed out. Though I'm satisfied with the current attribution of Mercury's size status to the IAU; the representation of dissenting views should be at the Pluto article. Nareek 03:32, 25 August 2006 (UTC)

I have restored the introductory sentence to say that Mercury is the "innermost and smallest planet" so that this article can be internally Wiki-consistent with the Pluto article and the Solar System template which both recognize Pluto as a dwarf planet and thus inherently support the notion that Mercury is the smallest planet in the solar system. I have, however, moved the dispute to a footnote where visitors may see that Mercury's status as the smallest planet is dependent on the recent IAU redefinition and that this is disputed by some unsourced group of people. Actual references to reputable disputes of the reclassification (something more than a blog entry) would be welcome and perhaps aid the Wiki-community in coming to a consensus as to how the dispute should be dealt with. However, I wish to make clear that from my perspective it is unacceptable to hedge Mercury's status as the smallest planet simply because of personal attachment to Pluto without adequate sourcing as to a reputable dispute concerning Pluto's status, particularly given the fact that elsewhere Misplaced Pages clearly supports the IAU redefinition as definitive. Bojangles04 16:22, 25 August 2006 (UTC)

I completely endorse the current first sentence and footnote. Couldn't have said it better myself. —Keenan Pepper 17:42, 25 August 2006 (UTC)

For sake of neutrality, I don't support adding the word "smallest" to the lead, especially to today's featured article. The lead should only contain information that is completely undisputed, and I believe it can do without a size ranking. So "Mercury is the innermost planet..." would be sufficient as the first sentence.
By the way, I generally support IAU's redefinition. However, we should put firm astronomical facts first and try not to fill the article with terminological and linguistical arguments. 80.235.56.16 20:15, 25 August 2006 (UTC)

Profanity Removal

There is destructive "graffiti" at the end of the first paragraph. I tried to edit it out but it does not appear on the editing page. Anyone know how we can get this removed?

It's seems to have been removed now.

Visibility Times

The statement "its greatest angular separation from the Sun (greatest elongation) is only 28.3° (it can only be seen in twilight)." came as a big surprise to me. Can any one please explain why Mercury cannot be seen at dawn as well, half a Mercurian year (44 days) later?

Thanks, --AVM 17:28, 25 August 2006 (UTC)

Twilight happens before dawn as well as after sunset. This seems to be the source of your confusion. Twilight just means that the sun is below the horizon but the sky is still light. —The preceding unsigned comment was added by 81.179.65.38 (talk) 23:09, 23 December 2006 (UTC).

Irony? Coincidence? Taunting?

I find it amusing that Mercury is the featured article on the Main Page the very same day that Pluto is on the Main Page "In the news" for its "demotion" from planet. Agent 86 22:10, 25 August 2006 (UTC)

Probably a coincidence, I think the chances are just too large...--Planetary 22:20, 25 August 2006 (UTC)

See Apophenia Raul654 23:57, 25 August 2006 (UTC)

Atmosphere?

The article states that Mercury's gravity is too small for it to hold any substatial atmosphere. Yet Titan's atmosphere is thicker than earths, despite having much less gravity than either Earth or Mars. So how can this be the reason Mercury has such a small atmoshere? 142.68.186.29 23:23, 25 August 2006 (UTC)

The sun blows away any gasses on mercury's surface. Raul654 23:56, 25 August 2006 (UTC)

It's not 'the Sun', it's the Solar wind. --AVM 03:29, 26 August 2006 (UTC)

And where does it originate? Picky picky ;) Raul654 03:15, 27 August 2006 (UTC)

Mercury does have an atmosphere, it's just so thin, it's not enough to affect the planet in any way. This atmosphere mostly results from the solar wind hitting the surface and interacting with the atoms of the rock. As for Titan's atmosphere, well, it's a bit of a mystery. That's why the Cassini spacecraft's observations of Titan arehighly important.--Planetary 05:01, 27 August 2006 (UTC)

The solar wind is much weaker at Titan's distance from the sun... It also spends almost all of its time inside Saturn's Magnetosphere which deflects solar wind aswell, stopping particles from ionizing n "blowing away" -- Nbound 23:04, 6 September 2006 (UTC)

According to some books and also German Misplaced Pages, the main chemical element in Mercury atmosphere is oxygen. --Wizzard 21:35, 9 October 2006 (UTC)

Recent Vandalism

I found this added to the end of the first paragraph from 210.15.211.182: "Mercury does not have any moons, but is a tiny bit bigger than our moon." GravityIsForSuckers 03:15, 30 August 2006 (UTC)

That's nice, but next time just delete it and don't mention it here. Vandals want attention.--Planetary 07:07, 30 August 2006 (UTC)

Acknowledged. GravityIsForSuckers 14:29, 30 August 2006 (UTC)

Smallest planet

I know we're all excited about Pluto no longer being a planet, but honestly the "smallest planet in the solar system" in the first sentence is going to be misleading to a lot of people. I had added the clarification "smallest of the 8 planets in the solar system" but I see that's been removed. Footnotes are also well and good, but the average person isn't going to read them. I strongly suggest being a bit more explicit about where it stands, at least until Pluto is no longer considered a planet by the average man on the street - probably a few more years at least. Stevage 10:03, 30 August 2006 (UTC)

Agreed -- Nbound 10:20, 30 August 2006 (UTC)

Atmosphere composition

Comparing the article to a page on NASA, im gettin different values... Are we using old figures here... or is NASA...

http://nssdc.gsfc.nasa.gov/planetary/factsheet/mercuryfact.html

-- Nbound 01:24, 7 September 2006 (UTC)

Comparing sources... both seem to be from the same publisher, same year with different authors...

Current Source: Potassium 31.7% Sodium 24.9% Atomic Oxygen 9.5% Argon 7.0% Helium 5.9% Molecular Oxygen 5.6% Nitrogen 5.2% Carbon dioxide 3.6% Water 3.4% Hydrogen 3.2%

Other Source: Atmospheric composition: 42% Oxygen (O2), 29% Sodium (Na), 22% Hydrogen (H2), 6% Helium (He), 0.5% Potassium (K), possible trace amounts of Argon (Ar), Carbon Dioxide (CO2), Water (H2O), Nitrogen (N2), Xenon (Xe), Krypton (Kr), Neon (Ne)

there seems to be a significant difference :| -- Nbound 01:28, 7 September 2006 (UTC)

Precession

The argument for the advance of Mercury's perihelion does not appear to view the orbit of Mercury from the perspective of the focus of its orbit, which is the centre of the sun. If this were applied and taken to its logical conclusion, by starting from the basis of the average velocity/mass and applying mass dilation in the hemisphere of the aphelion, a lower than average mass would result and thus a reduced velocity at the aphelion and an undershooting of its predicted position. And as the time Mercury spends in the hemisphere of the aphelion is far greater than that in the opposite, the result would be to more than cancel out the suggested perihelion advance, which in turn would have the overall effect of reversing the observed precession. I would be interested in an explanation. Romun 07:35, 11 September 2006 (UTC)

Requested move

Please discuss at Talk:Mercury --GW_Simulations_{User Page | Talk} 20:58, 12 September 2006 (UTC)

Hacker

A hacker has been at work on the Mercury (planet) article.

Observation section

Within the section titled "Observation", several things appear to be wrong:

• There is no apparent retrograd motion which lasts "8 to 15 days on either side of inferior conjunction"
• The maximal apparent elongations are not synchronized with Earth's rotation so the paragraph explaining a difference between northern and southern hemisphere makes no sense
• The phase of maximal apparent magnitude should vary between gibbous and crescent (because it depends on where Mercury is on its elliptic orbit and again this is not synchronized with Earth's orbit)

Icek 04:06, 17 November 2006 (UTC)

questions

how many moons are there???

Mercury has no moons. --Patteroast 19:35, 30 November 2006 (UTC)

what is the period of revolution for mercury?

Mercury's Double Sunrise

I think that this article should have a picture of the double sunrise, if possible. A better version of this graphic, ] Thanks, CarpD (^_^)

infobox

There is a discussion at Wikipedia_talk:WikiProject_Astronomical_objects#Planet_infobox_conventions_.28km_vs._AU_vs._miles.29 on standardizing the planet infoboxes, as well as the possibility of changing the planet diameter to radius. If you care about these things, let your opinion be heard there. Lunokhod 10:08, 4 December 2006 (UTC)

Vandalism

Vandalism spotted, but I am not able to edit, since the vandalism is not visible in edit mode. Salimi 19:08, 7 December 2006 (UTC)

If it's not visible when you go to edit it, that usually means that someone has already corrected it. Try reloading the page. siafu 19:13, 7 December 2006 (UTC)

Mercury heat

Mercury's heat may go up to 800 degree f, on the other side of the planet it may lower to 200 f below zero. It would take 85 Earth days to get around the sun.

Mercury has no moons, it does have volcanos. Mercury has more than 500 volcanos —The preceding unsigned comment was added by 66.32.42.130 (talk) 23:11, 15 January 2007 (UTC). Dominic Tarro Delray Beach Fl, (289-2969)

What just happened up there???-- Planetary (talk • contribs) 05:21, 16 January 2007 (UTC).

Core size

Hey everybody,

one http://messenger.jhuapl.edu/why_mercury/index.html one find an estimation for a core size with 65% of the whole planet size and NOT as written in the article 42%. My guess is 65% by mass = 42% by volume; both numbers being subject to assumtions which have credibility, but are unproven. Neil And what is meant by planet size, part of the volume or part of the total mass in Mercury's mass distribution? (Maybe this makes the different between Messanger-site and wikipedia?) Can someone comment on it? (Sorry for my poor English, I am just a German guy.) —The preceding unsigned comment was added by 129.206.107.106 (talk) 14:04, 3 February 2007 (UTC).

semi-minor-axis and orbital circumference

With the values of aphelion distance and perihelion distance from this article, I calculate the semi-minor-axis to = 56 671 637,01 km (believe me - i used my (by me) developed equation : b = sqr ( ((aph + per) / 2)² + ((aph - per) / 2)²) , but i dont want to explain the equation - its hard to write for me in English - test and compare it with every other accepted equation (for this planet, and if you want, for any other planet and object) - you will see : I'm right). With the same equation you can calculate the semi-minor-axis for article of planets, which only give the semi-MAJOR-axis. For the orbital circumference i have calculated with numerical integration the very exact value of : 359 976 796,63 km - test and compare it with the exact values of the semi-major-axis and semi-minor-axis, on this link : http://www.mathematik.ch/anwendungenmath/numint/ or any other exact equation for the circumference of an ellipse ...you will see, I'm right. I can't make the changes in this article, because I'm only signed up at the german wikipedia. But if nobody make this mathematically correct changes in this article maybe I sign up here, and make the changes for all planets, who gives the aphelion and perihelion distances, but only the semi-major-axis, and not the semi-minor-axis - and just a not-exactly orbital circumference, like in the Mercury-article. Lots of Greets from Austria, Pygmalion1 (24. February 2007 , 12:03 (CET))

The orbit of Mercury is not exactly an ellipse (it precesses, mostly), so the orbital circumference is not that of an ellipse and is actually very hard to specify. A difference in orbital circumference of .008% is not significant. The orbital circumference is only given to two places for this reason. Michaelbusch 18:12, 24 February 2007 (UTC)

If small differences are not important, why the exact values for aphelion distance, perihelion distance, etc. It could round it to the next 100 km's - not so important ;-) - only few 10^-4 % ... You know, what i mean ? I know : Mercury not closing the ellipse, but he has a "period" from which "he" start a knew "cyclus" and for this point, it can calculate a value for this "circumference". The value of 360 million kilometres is not "more right", when the track of mercury not an ellipse ;-) Or: for example, in this case i would write "approximately 360 Million kilometres" in the article, for orbital circumference. But the other exactly given values for the track, suggest's that the orbital circumference also exact - and that can't be in this case. Like i say : if it stand "appr. 360 Million" its ok - but not, if one value of track is given exactly, another value just "circa", and something like this - seems a little bit unprofessionell - maybe just for me. Greetings, Pygmalion1 (24. february 2007 (21:56 CET)) —The preceding unsigned comment was added by 84.112.1.134 (talk) 20:54, 24 February 2007 (UTC).

The orbital elements given in the article are osculating elements: at a particular reference time specified in the J2000 coordinates, they define an ellipse tangent to Mercury's position and velocity. That ellipse is defined to as accurately as we know the position of Mercury, which is at the sub-km level, and determines Mercury's trajectory given the positions, velocities, and masses of the other masses in the solar system, but Mercury is not on that ellipse. The orbital circumference could refer to the circumference of that ellipse (which you calculated), the distance Mercury travels in heliocentric coordinates between one perihelion and the next, the distance Mercury travels between passing a particular angle in the heliocentric frame and next passing that angle (i.e. when it has gone around the Sun), or the distance Mercury travels in a time equal to the period derived from the osculating elements. Because of this multitude of different definitions, giving orbital circumference to many places is non-sensical. I have added an 'approximate' mark to the infobox. Michaelbusch 21:44, 24 February 2007 (UTC)

You're right - but every planet has these specifications, - so the 'approximate'-mark would make sense at every planet (for the orbital circumference) ? I think so. Meanwhile the other thing : the semi-minor-axis is not important, when there was given a semi-major-axis ? I know: it suggests an ellipse for mercury - but that also does with the semi-major-axis, dont you think so ? If there is a semi-major-axis given, i think its good to give a semi-minor-axis too - like the articles for few other planets (they have the semi-minor-axis - a few ;-)). The 'approximate-mark' pleased me - thanks ;-) - and thanks for the explainings. Greetings, Pygmalion1 (and sorry again, for my weak english) (25. February, 10:30 (CET)) —The preceding unsigned comment was added by 84.112.1.134 (talk) 09:30, 25 February 2007 (UTC).

a semi-major axis is practically always given, a semi-minor hardly ever. The mathematical properties of the semi are very special, and it is constantly used in astronomical calculations. The semi-major is usually what people mean when they talk about "average" of "mean" distance. I agree with your earlier comment; we can round off a few more places. Saros136 09:56, 25 February 2007 (UTC)

Pygmalion1, there are other problems here, too.

First, b can be calculated using only the semi-major axis a and eccentricity e. I got a number only about 450 meters different than yours, ending with a .453 I used an infinite series formula for the circumference (which uses a and e), getting 359976739.60 km. I calculated it with Excel. (Then decided to check against an even higher-precision calculator-right on the money) The problem here is that the given numbers aren't precise enough to calculate to the nearest km. Lower e and higher a gives greater circumference, changing the numbers (adding or subtracting .5 and .000000005) gives a range of 6.6 km.

Actually, the actual perihelion varies by hundreds of km. Saros136 11:15, 25 February 2007 (UTC)

Thanks for your fast answer, and your work with the values of distances and orbital circumference. You handle the values good - but there are great differences between the formulas for ellipse's. Espescially, when the e-value is so high, like the mercury-e > 0.2 . I used two formulas - in the first : the one with the numeric integration (link in my first posting to this thread), and in the other the last equation for U at : http://de.wikipedia.org/Ellipse (at the bottom, with the number 6). These two formulas give the same (!) value for the orbital circumference. For the second equation i used my calculator with 13 digits precision (which could take the whole formula in one row). The second formula give a precision (error) for the orbital circumference, that is under 1 * 10^-9 . Thats less than 100 meters, for the mercury orbital circumference , so i trust these equations. But i know : there are many equations for the circumference of ellipses, which has a greater error (ignores the precission of the a, e, etc. - if the formula is not presice enough- the precise values dont matters). But thanks again for the verification of my calculations. Greetings, Pygmalion1 (26. February 2007 , 20:03 (CET)) —The preceding unsigned comment was added by 84.112.1.134 (talk) 19:03, 26 February 2007 (UTC).

Orbital Resonance Animation

I threw together an animated version of the orbital resonance graphic, I think it may help illustrate the idea a little better, at least to the layman, but I wanted to see what you all think first. --Age234 21:06, 11 March 2007 (UTC)

...And it's not showing up. It's there when you click on the broken image. Weird. --Age234 21:08, 11 March 2007 (UTC)

Very nice! I've seen Misplaced Pages occasionally choke on thumbnails like this, perhaps it's having trouble reducing an animated gif? You could try uploading a manually shrunken version in addition to the full-sized one. Also, I'd suggest putting the image on Wikimedia Commons instead, that way every language of Misplaced Pages can use it. Bryan Derksen 00:32, 15 March 2007 (UTC)

It would be a bit more "natural", imho, to have the arrow point to the sun at alternate perihelia rather than at alternate aphelia. —Tamfang 23:09, 30 April 2007 (UTC)

Magnetic field strengh?

I believe the strength of Mercury's magnetic field quoted (1% of Earth's) is in error. I have two astronomy textbooks ("Astronomy: The Solar System and Beyond" and "World's Apart") in front of me that say it is "about 10^-4 of earth's" and "about 1/3000th of earth's", respectively. 141.209.165.222 13:09, 14 March 2007 (UTC)

I've changed it to "about 0.1%", since that's well within an order of magnitude of 1/3000th. What edition is your copy of "Astronomy"? I put in a citation for the 4th edition (2004) edition since that's what Amazon handed me when I searched, and I expect the figure is unlikely to have changed much in other editions, but it's still good to ensure the citation is as accurate as possible. Bryan Derksen 00:25, 15 March 2007 (UTC)

Mercury the planet versus the element

Maybe if Misplaced Pages allows lowercase titles in the future, this article can be at Mercury while the article on element would be at mercury. Voortle 23:08, 29 March 2007 (UTC)

Surface feature?

In the main pic for this article, there is something that appears to be a prominant surface feature. It's the thing that looks like an arm with a Pac-Man puppet reaching down from the top of the planet. I couldn't find mention of that particular feature in the article, so I'm wondering if the "feature" is just an area of the planet that wasn't scanned by whatever probe or telescope took the picture. If somebody has that info, please include it in the article so I and others like me will be less confused! JSC ltd 15:34, 11 April 2007 (UTC)

At the image's description page Image:Reprocessed Mariner 10 image of Mercury.jpg it says "The smooth band is an area of which no images were taken", is that the feature you're referring to? I like your description of what it looks like. :) Bryan Derksen 18:00, 11 April 2007 (UTC)

Ah, yes. I should have remembered the old axiom, "when all else fails, read the image description!" Thanks for clearing this up for me. JSC ltd 15:35, 16 April 2007 (UTC)

Molten fluid interior

On Yahoo just minutes ago, apparently... Didn't put it in the article because it was made featured-status by likely-superior writers, who'd know better how to incorporate it. --Chr.K. 13:05, 4 May 2007 (UTC)

Cornell article Apparently there are other elements in the core with lower melting points. Brian Pearson 01:21, 6 May 2007 (UTC)

References for Sidebar

The Sidebar has only one reference, for one item, to detail where the information came from. Could someone actually support these data? This is also applicable to the other planets. --MatthewKarlsen

Pronuciation

I've checked dictionary.com and the IPA pronunciation is ˈmɜrkyəri. May i know why it is an ɹi behind? Thanks. —Sengkang 04:20, 18 July 2007 (UTC)

Rotation

"Despite its slow 176-day-long rotation..." Is this right? Elsewhere it says 58 days. Richard75 23:21, 21 July 2007 (UTC)

The 176-day figure is for Mercury's "day" (noon to noon), whereas the planet rotates every 58 days. In the context of the magnetosphere, I would guess that the planetary rotation is the significant detail. Thoughts? --Ckatz_spy 23:30, 21 July 2007 (UTC)

atmosphere composition

The article gives a variety of atmospheric constituents but is unreferenced. Here at NSSDC they give values which are very different. I would be inclined to believe NASA rather than the unreferenced values given in this article, at least that data is traceable. However, does anyone have a reference for the values that are currently in the article? Deuar 13:47, 3 August 2007 (UTC)

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