Talk:Mars/Archive 9

Opposition and minimum distance time.
The statement that the times of opposition and closest approach differ by up to 8.5 days does not mean the gap between successive oppostions varies by 8.5 days. That varies by much more. Example: in 2037, Mars reached a minimum of 73.838 Gm on Novemeber 11.3332, and eight days later, on Nov 19.382,5 reached opposition with a distance of 74.74066 Gm. The statement says the gap can be as much as eight and a half days. Saros136 (talk) 03:52, 1 October 2010 (UTC)
 * Thank you Saros for pointing out my error. I misunderstood the article and thought my clear brief statement was equivalent to what the article was trying to state.  I have since sought relevant information and correctly stated the relationship of successive oppositions with a reference in the article.  If that can be improved upon I welcome it.  --Fartherred (talk) 18:01, 2 October 2010 (UTC)
 * You're welcome. I doubt I could improve your edit. Saros136 (talk) 02:58, 3 October 2010 (UTC)

Opposition page
The opposition primer is referring to close approaches, not oppositions, in the bottom table. The wording is misleading, granted. Higher up they discuss the fact that close approaches do not occur at the same instant as an opposition, and in one table make it clear they refer to the approaches in the vicinity of the oppositions. Good, but some later numbers are referred to as the distance at oppositions. Inspection of the table shows that it is indeed the time of close approach. The Mars opposition of 2003 did not happen on the 27th. The other reference, that I deleted, only covers decades, not nearly enough the a sentence mentioning an approach distance that has not been reached for tens of thousands of years. I'm substituting the number for greatest close approaches, form Solex. Saros136 (talk) 22:01, 2 October 2010 (UTC)
 * Oh, by the way, my source for the far close approach distances was Solex. Saros136 (talk) 22:42, 2 October 2010 (UTC)
 * I've got more ideas on the subject and sentence. Stay tuned. Saros136 (talk) 22:02, 2 October 2010 (UTC)

Picture of Mars Caption
The caption under the picture of Mars says it's from the Hubble, but the pic info says it's a "Global mosaic of 102 Viking 1 Orbiter images" —Preceding unsigned comment added by 94.196.177.210 (talk) 09:33, 12 October 2010 (UTC)
 * You are correct. Thanks for the catch.&mdash;RJH (talk) 15:08, 12 October 2010 (UTC)

Unverified statement
The following statement was tagged as unverified in the article, so I'm moving it here for cleanup.
 * In the eight century, the Persian astronomer, Yaqūb ibn Tāriq, attempted to estimate the distance between the Earth and Mars in his Az-Zīj al-Mahlul min as-Sindhind li-Darajat Daraja.

The source listed for this statement was:



It looks like a valid source, but it does not confirm the statement. I haven't found any other source that will confirm the statement either, so at this point it is looking like possible misinformation. What the source does say is that the author of the Vishnu-Purâna lists distances between the planets, but there is nothing about them being measured using astronomical instruments. Yaqūb ibn Tāriq was noted mainly for his translation of Indian astronomy texts.

If somebody can provide a reliable source, then we can move the statement back into the article. Thanks.&mdash;RJH (talk) 18:06, 9 November 2010 (UTC)

metallicity
the first paragraph tells us this is a star with a lower metallicity then the sun, whence it is not supposed to easily form rocky planets, but also says it has a ten times more massive debris disk then the sun. i think that is kinda paradoxal, since my understanding is more debris actually promotes the formation of planets, so either the indicator of metallicity for rock is flawed (it surely seems so), and i think since secondary factors but the primary star play significant roles in the formation of debris disks it is the most logical,(the inference of planets for metallicity then being "spurious") or it remains completely unexplained that there is a relation between a lot of debris but still not a planet (wich seems illogical), i don't mind paradoxes much personally, they keep me thinking, but i wonder what it contributes to our understanding of star systems.24.132.171.225 (talk) 08:45, 7 February 2010 (UTC)
 * A debris disk isn't necessarily the same thing as a protoplanetary disk. A debris disk consisting of fine dust can decay over time, so the fact that Tau Ceti has a denser debris disk may only mean that its disk is much younger than the Sun's. Plus a debris disk doesn't contain much mass, so it may only require the collision of a couple of large asteroids, for example. I.e. it is random and subject to variation. Finally, the subject of a star being more likely to have planets when it has a higher metallicity is also a statistical quantity rather than an iron-clad rule. Thus there will be exceptions.&mdash;RJH (talk) 16:34, 7 February 2010 (UTC)

Proxima Centauri/Tau CETI
Someone showed me this, which might me of interest to the article. Don't know anything about anything though, and it's probably a hoax.

http://projectavalon.net/forum/showthread.php?t=18677 —Preceding unsigned comment added by 62.72.110.11 (talk) 09:48, 9 June 2010 (UTC)
 * Yes a hoax from a blog, and so unusable here. Extraordinary claims require extraordinary evidence.&mdash;RJH (talk) 20:57, 9 June 2010 (UTC)

Work needed
Hello everyone! This article currently appears near the top of the cleanup listing for featured articles, with six cleanup tags. Cleanup work needs to be completed on this article, or a featured article review may be in order. Please contact me on my talk page if you have any questions. Thank you! Dana boomer (talk) 17:51, 8 November 2010 (UTC)

Tags I have noticed: -- Kheider (talk) 18:51, 8 November 2010 (UTC)
 * Unlike Earth, Mars is now geologically and tectonically inactive
 * reactions between iron and the excess oxygen may be the reason Mars has much more[vague] iron in its crust and mantle than does the Earth
 * attempted to estimate the distance between the Earth and Mars in his (Az-Zīj al-Mahlul min as-Sindhind li-Darajat Daraja)


 * I thought I had this article cleaned up at one point after adding a bunch of cites and making revisions, but still it remained on the cleanup list. Seems like articles remain there in perpetuity once they are listed. Am I the only one helping take care of this page?&mdash;RJH (talk) 18:57, 8 November 2010 (UTC)


 * I think you are the primary. I keep a closer eye on the "Orbit and rotation" and "Close approach" sections, but I have not followed the rover missions in the last ~12 months. I think due to the on going Rover missions/orbiters this page gets hit regularly with cn tags.  Mars has 205 references, more than any planet.  Even the Earth has only 176 references. -- Kheider (talk) 19:13, 8 November 2010 (UTC)
 * The cleanup listings have been switched to a new bot, so they will be updated more. Check out the link I gave above to the featured articles cleanup listing - the same bot also does the project listings. Dana boomer (talk) 17:15, 9 November 2010 (UTC)
 * I think that all of the issues have been dealt with, although the table hasn't updated itself yet. Thanks.&mdash;RJH (talk) 20:13, 11 November 2010 (UTC)


 * Update the section on life on mars. Article claims that amounts of methane and formaldehyde could have come from volcanic/geologic process's. Mars is volcanically and geologically dead. HerrSticks (talk) 02:21, 13 November 2010 (UTC)
 * Mars is not geologically dead or even areologically (if that would be the right word for the analogous study of Ares) dead. It never developed plate tectonics, but had other tectonic activity.  It has no presently active volcanoes, but there is still heat flow from a hot core that might have molten regions.  The article is correct in suggesting that volcanic, geologic or biologic processes causing the methane would be consistent with our present state of knowledge.  It is a pity I cannot give a reference for that.  --Fartherred (talk) 04:40, 13 November 2010 (UTC)
 * Yes. Neukum et al (2004) states that, "calderas on five major volcanoes on Mars have undergone ... phases of activity as young as two million years, suggesting that the volcanoes are potentially still active today".&mdash;RJH (talk) 20:03, 16 November 2010 (UTC)

I have a few comments to add to the first two bulleted tag items above. To say "Unlike Earth, Mars is now geologically and tectonically inactive" is imprecise and probably incorrect. First, what does "geologically" inactive mean? Mars has a lot of active geological processes today (e.g. mass wasting, wind erosion and deposition, etc.). Second, if the phrase is meant to mean no internal (volcanic, tectonic) processes are active, this would have to be based on seismology and heat flow data. Only one seismometer has operated on Mars (Viking 2), which did record a low-magnitude quake. Golombek et al. (1992) suggests that Mars remains seismically active at the present time. Mars is probably still volcanically active too, although at a very low rate. We currently have no heat-flow data, so it's unknown exactly how warm Mars' interior currently is or isn't.

As for the second item, my understanding is that the anlayses of Martian meteorites and models of Mars' bulk density suggest that its mantle is enriched in iron as iron oxide (FeO). Some theories hold that Mars accreted from two populations of plantesimals: One was rich in metallic iron, and the other rich in water. The two were able to chemically interact early in Mars' history (before all the iron sank to the core) to form FeO and hydrogen, with the hydrogen readily escaping into space. See Boyce, J. (2009) The Smithsonian Book of Mars, for a discussion of the topic for general readers, and Barlow, N. (2008). Mars: An Introduction to Its Interior, Surface and Atmosphere, for more details. Hope this adds to the discussion. Schaffman (talk) 23:14, 11 December 2010 (UTC)

Martian temperatures
The article says: "Martian surface temperatures vary from lows of about -87 °C during the polar winters to highs of up to -5 °C in summers."

But another source (MarsNews.com :: Focus Sections :: The Planet Mars) says: "While the average temperature on Mars is about 218 K (-55 °C, -67 F), Martian surface temperatures range widely from as little as 140 K (-133 °C, -207 F) at the winter pole to almost 300 K (27 °C, 80 F) on the dayside during summer" (I suppose this is in the equatorial areas).

Another interesting fact is this: "The meteorology mast on the lander has observed a rapid drop-off in temperatures just a few feet above the surface, and one detailed 24-hour measurement set revealed temperature flucuations of 30-40 degrees Fahrenheit in a matter of minutes." MARS PATHFINDER WINDS DOWN AFTER PHENOMENAL MISSION. But this was written in 1997, so new relevant information could have collected since then. Hipporoo (talk) 04:55, 5 December 2010 (UTC)
 * Mmm, I guess it depends on who you trust to give you the temperature information: the people who send spacecraft to Mars or some generic web site. It would be nice to use primary sources for that information though.&mdash;RJH (talk) 23:32, 6 December 2010 (UTC)

We've known for a long time that the temperature at the winter poles can drop to 140K, the condensation temperature of CO2 on Mars [Leighton, R.B.; Murray, B.C. (1966). Behavior of Carbon Dioxide and Other Volatiles on Mars. Science, 153(3732), 136–144.] This is about -133° C. The way the article is worded now: "...lows of about -87 °C during the polar winters.." is wrong and needs to be fixed.Schaffman (talk) 22:08, 11 December 2010 (UTC) 22:06, 11 December 2010 (UTC)


 * That "about -87 °C" (while still apparently wrong) looks like one of those over accurate approximations we get from sloppy conversions. I'll bet someone took the quite rough figure of "about -125 °F" and converted it to Celsius. The 7 on the end implies a precision that was never in the original figure. Gee I wish America would properly metricate, then all this confusion would go away. HiLo48 (talk) 22:32, 11 December 2010 (UTC)

Yep, we'd have had a successful Mars Climate Orbiter mission, too. Schaffman (talk) 00:00, 12 December 2010 (UTC)

is there life on mars
is there life on mars —Preceding unsigned comment added by 70.24.115.84 (talk) 23:15, 6 December 2010 (UTC)
 * It's a definite maybe.&mdash;RJH (talk) 23:29, 6 December 2010 (UTC)
 * You are going to want to think along the lines of extremophiles. -- Kheider (talk) 23:39, 6 December 2010 (UTC)

Nobody knows. Schaffman (talk) 22:25, 11 December 2010 (UTC)

Phobos Lifespan
Hello everyone! The article states in relation to Phobos "In about 50 million years it will either crash into Mars’ surface or break up into a ring structure around the planet." This information was taken from http://nineplanets.org/phobos.html By Bill Arnett; last updated: 2004 Nov 20. However on May 10th 2008 Dr. Bijay Kumar Sharma submitted an article about this subject. In the article he recalculates the descent of Phobos and found that Phobos has much less time left and will crash into Mars in 10.4 Million Years. He also states that Phobos will reach the Roche Limit in 7.6 Million Years, at that point Phobos will break apart into a Saturn-like ring. Information about Dr. Sharma's article can be found at: http://arxiv.org/abs/0805.1454 Here is a direct link to the article itself in PDF format: http://arxiv.org/ftp/arxiv/papers/0805/0805.1454.pdf WNSwins (talk) 02:41, 13 December 2010 (UTC)

Dates of Martian time periods are off
The age of the Hesperian/Amazonian boundary given in the article (1.8 bya) is a lot younger than what is most commonly cited. Although the absolute age is very uncertain and could vary by a factor of 2, I've seen it usually given as somewhere between 3.2 and 2.0 bya. (See Hartmann and Neukum, 2001 and Hartmann, 2005.) A readily accessible discussion of this is in Hartmann, W.K. (2003) Traveller's Guide to Mars; Workman: New York, pp. 33-34. Schaffman (talk) 20:10, 18 December 2010 (UTC)

Surface pressure of atmosphere
Is the atmospheric pressure indicated representative of the mass of the atmosphere independent of gravitation, or is it as per definition of pascals, a measure of actual pressure exerted in the Martian gravity field? Lucy Skywalker (talk) 21:47, 2 January 2011 (UTC)

acidic or alkaline surface
In the first paragraph under the 'Life' section it is stated that the Martian surface is acidic. However in the third paragraph in the same section it is stated that the soil has a very alkaline pH. These appear to be contradictory statements. Can someone who knows the correct conditions of the surface/soil. please resolve this apparent conflict? --Ddraig2 (talk) 01:01, 4 January 2011 (UTC)


 * I presume the two statements in question are:
 * Soil: "...the Martian soil has a basic acidity of 8.3..."
 * Life: "...that the soil has a very alkaline pH and it contains magnesium, sodium, potassium and chloride."
 * Both of these statements are in full agreement. However, using the word 'acidity' could be confusing to some (and obviously is).  Does changing that word to 'pH' clear things up? --Xession (talk) 20:16, 4 January 2011 (UTC)

Actually I was referring to the last sentence in the 1st paragraph: "....Martian surface would have been too salty and acidic to support terrestrial life". A pH of 8.3 is not acidic under anyone's definition. I would also comment that the statement 'basic acidity' is an oxymoron. I am a chemist and the use of the term 'acidity' as a synonym for 'pH' while popularly used is scientifically unsupportable. Something can be acidic, or basic, or neutral (Ddraig2).

Edit request from Nightdave, 18 January 2011
NASA Mars resources: http://mars.jpl.nasa.gov

Nightdave (talk) 20:47, 18 January 2011 (UTC)


 * Exactly what is your request? HiLo48 (talk) 21:47, 18 January 2011 (UTC)
 * I'll be happy to make the edit for you when you say what you want edited specifically. I n k a 888  23:17, 18 January 2011 (UTC)

Length
Is there any area of this article that could be shunted off to a sub-article to trim its massive length?  Serendi pod ous  09:31, 26 January 2011 (UTC)


 * The article is already sectioned off into numerous articles leaving just abroad overview of everything that is Mars in this article. Generally the length of an article is not an issue so long as the information is complete and doesn't repeat information continuously throughout. In the case of Mars there's an incredible amount of information and it warrants a long, thorough page. --Xession (talk) 14:26, 26 January 2011 (UTC)


 * There's a few steps that I think could be taken. To me, some of the Exploration section seems a little too detailed and could be better summarized. (For example, I think it only needs to say when a probe arrived at Mars; not when it was launched.) The "Future Missions" section could be moved to its own article and summarized in a couple of sentences. There are also a few paragraphs scattered throughout the article that seem to cover tactical details at an excessive level and could be better summarized. (Example: "Two photographs, taken six years apart...".) I also wonder whether we really need to know what spacecraft discovered specific tactical details on Mars? Thanks.&mdash;RJH (talk) 16:27, 26 January 2011 (UTC)
 * Yes, each probe has its own article for such dry details. Look for anything that has its own article and trim away... Abductive  (reasoning) 23:46, 28 January 2011 (UTC)

Pressure at the bottom of Valles Marineris?
If I am reading the section correctly, the pressure of Mars' atmosphere changes more slowly with altitude than it does on Earth. So does anyone know what the pressure would be at the bottom of the deep sections of Valles Marineris, 7 km down. Maury Markowitz (talk) 22:27, 28 January 2011 (UTC)


 * Hellas Planitia is actually the lowest point on Mars at a little more than 7-kilometers deep. The article states that the pressure at the deepest point of the basin should be around 1,155 Pa (.17 psi) while the mean surface pressure of Mars is 636 Pa (0.09 psi).  Valles Marineris should have a comparable pressure at the lowest depths. --Xession (talk) 22:45, 28 January 2011 (UTC)

Original units were clearer?
According to IUPAC recommendations (see IUPAC Green Book http://old.iupac.org/publications/books/gbook/green_book_2ed.pdf and also page 1387-1388 of http://www.iupac.org/publications/pac/67/8/1377/pdf), the units ppm, ppb and ppt should not be used. That's why I have replaced them. Also, I think that chemists as well as astronomers understand the meaning of the prefixes mu for 1E-6 and n for 1E-9. Please let's discuss this here and not start an edit war! RolfSander (talk) 22:52, 4 March 2011 (UTC)
 * Wikipedia has it's own standards. For scientific articles, this means using "the units employed in the current scientific literature on that topic". There are a large... okay, huge number of scientific journal articles about Mars that employ ppm.&mdash;RJH (talk) 23:32, 4 March 2011 (UTC)
 * I can see your point now, thanks for the link. I work in atmospheric chemistry. Publications in this field currently have a mix of the old "ppb" and the new "nmol/mol". Although "ppb" still occurs more often, there is a trend to the new notation. Thus, I think both would be consistent with the WP-MOS recommendation which says: "In scientific articles, use the units employed in the current scientific literature on that topic. This will usually be SI, but not always". However, I see another problem with the old units. The WP-MOS says: "Only in the rarest of instances should ambiguous units be used". I can see at least 3 ambiguities with the old units:

RolfSander (talk) 00:53, 5 March 2011 (UTC)
 * 1) "ppb" may either refer to mass fraction or mole fraction, which are quite different.
 * 2) The "b" in "ppb" stands for billion, which can either be 1E9 or 1E12, see Long and short scales.
 * 3) "ppt" is even worse: if may either refer to parts per trillion (1E-12) or to parts per thousand (1E-3).
 * I've asked for input from the members of the WikiProject Astronomical Object. If the consensus turns out to be to convert the units and if #1 is a problem, then I'm not sure a straight conversion of units would work. We would need to find appropriate sources with units in "nmol/mol".&mdash;RJH (talk) 18:19, 5 March 2011 (UTC)
 * My immediate reaction is to use ppm. If ppb is considered too ambiguous, fractions less than 1ppm can be expressed as eg. 4×10-2 ppm. I know that's weird, and contrary to the 'official' units, but astronomy is full of such things (e.g. wavelengths in angstroms, distances in parsecs etc). Besides, IUPAC is not the relevant body to make such recommendations; the IAU is. Notice that the NASA-produced File:Martian Methane Map.jpg uses parts per billion. Of course any such ppm usage should state whether it is by mass or by number. Modest Genius talk 18:35, 5 March 2011 (UTC)
 * If IAU is the relevant body for you, do you know if they have any recommendations regarding this question?RolfSander (talk) 18:57, 5 March 2011 (UTC)
 * On concentrations, I'm not aware of any. Their web page on units discusses SI units etc, but is of no use here because 1) that deals only with dimensional units, but concentration is dimensionless, 2) the page clearly states that some very common astronomical units (angstrom, micron etc) should not be used, which is clearly neither enforced nor supported by the community, and 3) the 'official' recommendations should serve to inform us, but not bind us - the WP policy states 'use the units employed in the current scientific literature', which is not necessarily what the standards bodies proclaim is the 'correct' unit. Modest Genius talk 01:41, 6 March 2011 (UTC)
 * You are right, using the recommended SI units is clearly neither enforced nor supported by the community. I have a hard time understanding why this is so. This is not nitpicking as some people may think. Refusing to use SI units can even destroy a spacecraft. Here on the Mars page readers probably know what I refer to. If not, take a look at the Mars Climate Orbiter. RolfSander (talk) 16:31, 6 March 2011 (UTC)
 * Yes I do. In the case of Wikipedia, much of the style guide was built through a process of consensus. In some instances there were presumably objections to blanket enforcement of the SI standard; specifically when certain fields have preferred non-SI unit conventions and particularly when the non-SU units are more convenient to use. (For example, using cgs for describing planetary density or Janskys in radio astronomy.) I think it is just going to take time to change over.&mdash;RJH (talk) 23:36, 6 March 2011 (UTC)
 * I'm well aware of MCO, and could get into a very detailed discussion about why certain units have or have not been adopted by practising scientists, and the costs and benefits those entail. But this is not a forum, and this tangential direction of discussion is not helping us reach a consensus as to which units of atmospheric concentration are best to use on wikipedia. Modest Genius talk 23:54, 6 March 2011 (UTC)
 * Ok, let me try to summarize the current status then: RolfSander prefers using SI units, Modest Genius and RJH don't. No consensus here. However, I hope we all agree with the WP-MOS which says: "Only in the rarest of instances should ambiguous units be used". Here is my suggestion for a consensus: We keep ppm and ppb but add the information to all occurences if this is a mass fraction (kg/kg) or a mole fraction (mol/mol). AFAICS, on the Mars page all numbers are mole fractions. RolfSander (talk) 20:43, 7 March 2011 (UTC)
 * Certainly, that seems sensible to me. Of course ppm / ppb should never be used without stating whether they're by mass or by number. Either a footnote or a simple 'mass fraction' in the prose would be fine. Modest Genius talk 21:13, 7 March 2011 (UTC)
 * Good, looks like we've found a consensus. I'd like to wait for a comment from RJH though. BTW: "...should never be used without stating whether they're by mass or by number..." They NEVER should but they ALWAYS are! RolfSander (talk) 22:11, 7 March 2011 (UTC)

I don't believe that this information is necessarily readily available. For example, the NASA Mars Fact Sheet provides abundances in ppm without specifying the type. I suspect the convention is to use whatever form is most readily measured spectroscopically, which I would presume is by number.&mdash;RJH (talk) 16:10, 8 March 2011 (UTC)
 * Interesting! Even you (although very familiar with the topic) have to admit that you don't know for sure what ppm means here. I cannot understand why you are opposed to using non-ambigous units at least in the cases where we do know what is meant. Anyway, I checked the CH4 value in the original paper by Formisano et al. They use the expression "ppbv". Assuming an ideal gas, this is equal to mole fraction. Thus I assume that the other numbers are also mole fractions. RolfSander (talk) 19:53, 8 March 2011 (UTC)
 * Right, ppm in the sense of "by volume" appears to be the common usage in the astronomical literature for planetary atmospheres. We're following what is available in the literature, which is easier to cite and is a Wikipedia standard.&mdash;RJH (talk) 21:10, 8 March 2011 (UTC)

Water-worn structures on Mars
The section about water-worn structures on Mars under Hydrology is muddled (as was the source material under Water on Mars, to be fair). The description of the outflow channels is OK, but IMO spends too long on reasoning against the water origin without also presenting the evidence for water origin. More pressingly though, as in the daughter article, there's a critical confusion here between the dendritic, Noachian, valley networks and the huge, single thread, Hesperian outflow channels. These are fundamentally different things, well recognised as such in the literature, and it is in fact the valley networks that present the more compelling evidence for a warm, wet early Mars (which is surely where this section should be headed). This is totally unclear as the article stands.

If no-one has any comments, I'll make a discreet rewrite of this section for clarity at some point in the near future. And given the FA status of the article, I promise not to muck it up. And also not to noticeably increase the length!

DanHobley (talk) 03:16, 31 March 2011 (UTC)
 * I'd say, WP:SOFIXIT applies here. As long as WP:NPOV is maintained, I don't think anybody is going to complain too much about an improvement to the article. Thank you. Regards, RJH (talk) 14:44, 31 March 2011 (UTC)

Epoch vs. Period in geologic history section
I know this will sound pedantic to some, but Noachian, Hesperian, and Amazonian are periods, not epochs. The epochs are subdivisions of the periods (e.g. early Noachian, middle Noachian, late Noachian, etc.). I think the article should comply with standard stratigraphic nomenclature. I can change this if no one objects. Schaffman (talk) 14:01, 18 April 2011 (UTC)
 * Unfortunately the scholarly literature is pretty inconsistent about this. There are more uses of "Nochain epoch" than there are of "Nochian period", for example. I think we should probably discuss it first.&mdash;RJH (talk) 16:32, 18 April 2011 (UTC)
 * You're right; the literature is inconsistent. I'm curious though where you got the "more uses of Noachian epoch than period..." from. I did a Google Scholar search and got the opposite result. There were nearly twice as many instances of Noachian period over Noachian epoch (193 vs. 100). The inconsistancy in the literature doesn't surprise me too much. Not all Mars researchers are familiar with stratigraphic principles, and journal editors don't always do their job well. Still, I'm curious to hear from others on the topic. You got me thinking that maybe the period/epoch convention is strictly a North American thing. If so, I stand corrected. Schaffman (talk) 19:57, 18 April 2011 (UTC)
 * You're correct, there are more instances of "Noachian Period"; I think I was doing some odd search combinations, which gave me the opposite result. I added a request for comment on the Astronomical Objects WikiProject.&mdash;RJH (talk) 20:10, 18 April 2011 (UTC)
 * I agree, it probably ought to be period. Though it's only just occurred to me that it would be far more sensible if it were eon, based on comparison to the lengths of divisions on Earth! But there you go, it's not. DanHobley (talk) 00:33, 19 April 2011 (UTC)


 * I think the reason the time length of periods on Mars is so large compared to Earth is due to inadequate resolution, absence of a fossil record to examine, and the less dynamic nature of Mars’ geologic history. The time periods are based on the stratigraphic relationships of rock units that can be mapped from space (or historically for the Moon, through telescopes). For better or worse, these mappable units are grouped into time-stratigraphic systems (for Mars: Noachian, Hesperian, Amazonian). The geologic time equivalent of system (at least in North America) is the period. On Earth, the time-stratigraphic equivalent of eon is eonothem, a term rarely used, and one certainly not in use when planetary geologic mapping began in the 1960s and 70s. Schaffman (talk) 13:48, 19 April 2011 (UTC)
 * It turns out the Geology of Mars article has been using 'Period' for some time. It would make sense to be consistent between the two and use 'Period' in this article as well. Thanks. Regards, RJH (talk) 20:19, 19 April 2011 (UTC)
 * As there was no further discussion, I implemented the agreed upon change of 'epoch' to 'period'. Thank you.&mdash;RJH (talk) 21:13, 25 April 2011 (UTC)

Degrees C and F, relative
In the Climate section it says that temperatures in the south varies by 30C (86F) more than they do in the north. This is wrong as it is a relative temperature not an absolute one 30C corresponds only to 54F. —Preceding unsigned comment added by 93.162.119.14 (talk) 05:38, 27 April 2011 (UTC)
 * Good catch! Thanks. Regards, RJH (talk) 21:36, 27 April 2011 (UTC)

Planetary embryo (?)
"Hf-W-Th evidence for rapid growth of Mars and its status as a planetary embryo" by Dauphas and Pourmand: Mars allegedly is a "oligarch", a protoplanet, while Earth is some kind of later collision product. Rursus dixit. ( m bork3 !) 10:43, 31 May 2011 (UTC)
 * That's interesting, but it appears to be a preliminary result at this time. Regards, RJH (talk) 15:04, 3 June 2011 (UTC)

Edit request from 198.102.153.2, 2 June 2011
Please change 

to 

This rest of the article is using multiple image and this will make the caption font and image margins uniform throughout the article. Thank you.

198.102.153.2 (talk) 22:32, 2 June 2011 (UTC)
 * ✅. Thanks! Samwb123T-C-E 02:20, 3 June 2011 (UTC)

Trimming images
I did some trimming of the images in this article because it was getting steadily bloated with new additions, which significantly impacts the article download time. There is already a Mars gallery on the commons. Regards, RJH (talk) 19:09, 6 June 2011 (UTC)

areoid vs "sea level"
A recent edit summary:
 * (added reference and mention to the ""areoid"" of Mars -- which is another term for its mean surface gravity, a measure analogous to zero sea level on Earth.)

On Earth, sea level may be the median altitude but it is not the mean altitude, and local gravity is not constant on the geoid (though potential energy ought to be). Nor is "sea level" on Mars defined as a mean of anything.

The geoid is defined as a surface perpendicular to local gravity, which on the oceans coincides with mean sea level. An areoid can be defined similarly, but I'm less sure that atmospheric pressure (which defines 'sea level' on Mars) would be constant on such a surface, and I'm confident that local gravity would not be. —Tamfang (talk) 04:26, 28 June 2011 (UTC)


 * Yes, I agree. Though the reference to sea level is probably the clearest way to describe what this is is a single sentence - and I think more detail would be inappropriate here. I've made some minor adjustments... feel free to change again. DanHobley (talk) 13:34, 1 July 2011 (UTC)

surface gravity
Equatorial surface gravity is given as 3.711 m/s² = 0.376 g; but 3.711/9.81 = 0.378. —Tamfang (talk) 03:50, 26 March 2011 (UTC)
 * Yes and I don't think we need three digits anyway. Most sources list it as 0.38.&mdash;RJH (talk) 17:17, 26 March 2011 (UTC)

What are the extremes (polar and equatorial)? —Tamfang (talk) 19:16, 26 March 2011 (UTC)
 * On Earth at least, the surface gravity at the equator is about 1/291 (=0.34%) less than at the Pole. From the centripetal force article, F = mrω2. The ω is about the same for Earth and Mars, so the Force would be reduced by the ratio of the two planets radii (0.53). Assuming I got that right, then the percentage is slightly higher than on the Earth (0.53/0.38 = &times;1.4).&mdash;RJH (talk)
 * Rotation isn't the only thing contributing to the difference. —Tamfang (talk) 23:37, 5 April 2011 (UTC)
 * Besides radius, what else are you suggesting?&mdash;RJH (talk) 15:02, 6 April 2011 (UTC)
 * What does 0.53/0.38 get you? —Tamfang (talk) 23:58, 6 April 2011 (UTC)
 * The radius is 0.53 Earth, while the gravity is 0.38 Earth. Thus the ratio of the centripetal force to the gravitational force is 1.4 times that of the Earth. 1.4 &times; 0.34% = 0.48%. So, for this back of the envelope calculation, the gravity at the equator is roughly 0.48% less than the gravity at the pole. That doesn't match your result below though, which shows a reduction of 1.63%. Shrug.&mdash;RJH (talk) 15:59, 7 April 2011 (UTC)

Using the given numbers for mass, equatorial and polar radius, and equatorial rotation speed, and applying the spherical approximation, I get polar gravity 3.7582 and equatorial gravity 3.6970 m/s²; but GM/R² is accurate only when the mass is spherically symmetric, and besides I don't know how much the Tharsis bulge affects the gravity. So I wish I knew where to look for better estimates of the gravity at the poles and at the top of Pavonis Mons. —Tamfang (talk) 23:58, 6 April 2011 (UTC)
 * I'm pretty sure these values are out there in the literature, but it's proving tricky to track down. I can tell you though that the gravitational anomaly at long wavelengths across the Tharsis bulge is about 0.5 Gal (i.e., 0.005ms^-2), and the anomaly associated with the specific volcanoes around that area is between 1 and 3 Gal (i.e., 0.01-0.03ms^-2, c. 1% of total gravity!) - see papers by Smith et al. (1999; Science) and McKenzie et al. (2002; EPSL). I suspect this huge bulge in the gravity field in one hemisphere is why you don't see the actual figures for g at the pole and "equator" quoted very often. Nevertheless, I'll try to find a paper that actually gives absolute values (probably in the Viking literature from the late 70s early 80s). And yes, I think you're right that there's more to the calculation than radius & rotational speed - the way to do it properly appears to require solving for the spherical harmonics, not just going for the spherical approximation. DanHobley (talk) 13:27, 7 April 2011 (UTC)

Infact,Mars can be lived on!It might have some water.It might or might not have oxegin.But that is ok.Because we can take care of that.The best way of getting oxegin is planting plants on it. — Preceding unsigned comment added by 137harnsberrya (talk • contribs) 00:28, 6 August 2011 (UTC)


 * Dan, the surface gravity at the pole is given as 3.758 m/s2 and 3.711 m/s2 at the equator in H.H. Kieffer et al. (1992) Mars; University of AZ Press, p. 29. This is based on the difference between equatorial and polar radius (GM/R2). Not sure how these numbers have changed with more recent geophysical data, but that's what's out there in the older literature. Schaffman (talk) 13:22, 18 April 2011 (UTC)


 * OK, I think I get this now. The spheroid (AKA, "geoid", "areoid"), which is the 1st harmonic spherical approximation - the one that lets the planet bulge out at the equator, but nothing else - gives values of 3.758 and 3.711 m/s2 at the pole and equator respectively. This is calculated purely in abstract, based on known bulk planetary density and geometry. However, more recent satellite observations of the actual magnetic field have shown that the volcanoes (and associated ?basaltic intrusions) really do affect local gravity at least a bit, with the amount of perturbation to the areoid you see depending on the scale you're looking at - as you would expect. The maps of the gravitational anomalies in the Smith and McKenzie papers are both describing deviations away from this (hypothetical) areoid. Hence, the answer to Tamfang's question is - it depends on the scale you look at. Tharsis gives a broad wavelength bulge of about 0.5 Gal, but with local anomalies corresponding to each volcano of between 1 and 3 Gal (= 0.01-0.03 m/s2, c. 1% of the total gravity, c. 25%-75% of the difference in average gravity between the pole and equator!). DanHobley (talk) 15:54, 29 April 2011 (UTC)


 * Of course, the assumption that gravity figures are constant over time, is not entirely correct. Cheers, Greenodd (talk) 23:37, 11 August 2011 (UTC)

Differences in the sources
17:38, 24 January 2015 (UTC)

Okay...
if anyone wants to use the ROSETTA Mars image...

Go upload it yourself.

Also make sure it has sufficient copyright. — Preceding unsigned comment added by TheWhistleGag (talk • contribs) 02:04, 24 February 2015 (UTC)


 * As has been explained, the Rosetta image of Mars was taken using its OSIRIS instrument, images from which are not freely licensed. So no, others may not upload it themselves. — Huntster (t @ c) 03:22, 24 February 2015 (UTC)


 * Alright.
 * Then just use something from NASA, please. And something not from Hubble.

Lead image
Comparison: Different Views of Mars (from top left):
 * Mars as seen from the Viking 1 Orbiter (1998) - Global Mars (57mb TIF-file)
 * Mars as seen from the Viking 1 Orbiter (1980-A) - Syrtis Major
 * Mars as seen from the Viking 1 Orbiter (1980-B) - Valles Marineris
 * Mars as seen from the Viking 1 Orbiter (1980-C) - Valles Marineris
 * Mars as seen from the Hubble-2 Space Telescope (2003).

Okay, this section is long overdue. Looks like we have three candidates for lead image: a composite from MGS data, an image from the Rosetta flyby, and an image from Hubble (all pictured at right). Let's all say which one we prefer and give our reasoning to try to reach a consensus on this.
 * Mars as seen from the Mars Global Surveyor (2000)

For me, the most important criterion that planet lead images should be judged by is likeness to life. I believe that the average Wikipedia reader expects the lead image to depict the planet as it would actually appear and that to show it any other way would be misleading. For this reason, I object to using the MGS composite as the lead image. It is by far the most detailed, but it bears little resemblance to what Mars actually looks like from the perspective shown in the image. Essentially, it is a creative way to display images taken from low orbit, from which perspective the surface looks very different than from the distant perspective artificially shown in the composite image. Look around the edges, especially in the polar regions, and you can see very clear artifacts from the wrapping of flat, low-altitude images onto a sphere. It would be fine to use this image elsewhere in the article, but I think the lead should show the planet as it actually appears.

In accordance with "likeness to life", my first choice is the Rosetta flyby image, a single capture from a spacecraft in the vicinity of Mars. I strongly prefer that the image be used as it was originally posted, without the "enhanced" color processing, which makes the picture look prettier but less true-color and thus less accurate. The ESA website has the "enhanced" color image labeled as true-color, so I stand corrected. I understand that this image also has potential copyright issues, and I of course do not support it if those are not resolved.

My second choice is the Hubble image. As a telescopic image, it is not as preferable as one actually taken in the vicinity of Mars, but it is still truer to life than the MGS composite. If the color of the Rosetta image is not changed back to the original or if the copyright issues prove unresolvable, this is my first choice. A2soup (talk) 19:52, 22 February 2015 (UTC)


 * FWIW - Thank you for posting - I *entirely* agree with you - the preferred image would be the "Mars ESA Rosetta image" - But - the ESA copyright policy is problematic for Wikipedia use and such images are generally speedily deleted (User:Huntster has a lot of experience with such ESA images on Wikipedia and may be helpful in this instance as well I would think) - my second choice would also be the "Mars Hubble image" - seems this image may be the most popular on Wikipedia: see "Local English usage" and "Global usage" - in any case - Thanks again for posting - and - Enjoy! :) Drbogdan (talk) 20:34, 22 February 2015 (UTC)
 * The Hubble image is, by far, of the lowest quality, so is not option. The Rosetta image, in its current high-resolution version but back in true color, is a good option IMO. Else, the MGS image is a basically equally fine IMO. --JorisvS (talk) 21:42, 22 February 2015 (UTC)
 * The Rosetta image is absolutely a no-go. The image is by the OSIRIS instrument operated by the Max Planck Institute, and those images are not released under a free license like the NAVCAM images are. Note that it comes from http://www.planetary.org/blogs/emily-lakdawalla/2012/3340.html. Let me go look around and see if there are any other images that would suffice for the infobox. I personally don't see an issue with using the Hubble image despite its size. It may be the best real representative image of the planet. — Huntster (t @ c) 21:59, 22 February 2015 (UTC)
 * Regarding the source of the Rosetta image, it looks like the current version is actually directly from the ESA website. A2soup (talk) 22:18, 22 February 2015 (UTC)
 * Yeah, sorry, I was referring to the original image uploaded. Regardless, still an OSIRIS image and not freely licensed. — Huntster (t @ c) 23:08, 22 February 2015 (UTC)
 * The HST image is of low quality compared to the other two. The MGS is a composite, so what? Composites are very common in order to get high-resolution images of astronomical objects, which could not have been acquired at a large enough distance to image the entire object. --JorisvS (talk) 11:29, 23 February 2015 (UTC)
 * For sure, global composites from low-altitude images are definitely useful for presenting detailed information on global geography. The problem is that they don't accurately represent what the planet looks like, which I think should be the priority for the infobox to avoid misleading readers. To give a more dramatic but equivalent example, this lovely high-resolution radar composite of Venus is not in the infobox. It shows much more information than the infobox image, but misrepresents what Venus actually looks like. So it goes in the section about Venus's surface, which I think is also the proper place for the MGS composite in this article. A2soup (talk) 17:55, 23 February 2015 (UTC)
 * That's a) a radar image, and b) has less than 100% coverage. This means it is totally different from what it would look like in the visual. What are the biggest differences with how Mars would have looked at the time, exactly? --JorisvS (talk) 18:01, 23 February 2015 (UTC)
 * It would have looked much more like the Rosetta and Hubble images, which resemble each other but not the MGS composite. So, as far as I can tell, the biggest differences are that surface geography would have been much less visible, the poles would have had larger apparent white regions, and the poles would have had fewer projection artifacts. Also, "at that time" doesn't mean much here, since the MGS images were taken over a significant time span. A2soup (talk) 18:13, 23 February 2015 (UTC)


 * I've removed the Rosetta image at right as it is not acceptable, and replaced it with another Hubble image for consideration ("Hubble image 2"). While, again, not of the highest resolution, I like that it shows acceptable surface texture and polar ice, and I suppose atmosphere on the limbs. As for the composite image, while it may be of higher resolution, it simply feels...off. It doesn't feel like a natural, or classicly recognizable, representation of Mars. I just don't know that I could give it my vote. — Huntster (t @ c) 04:14, 24 February 2015 (UTC)
 * There must be other ones out there, one's that have less distortion than the MGS image, but have been made from orbit (and hence less fuzzy than the HST images). --JorisvS (talk) 09:58, 24 February 2015 (UTC)

Yes - the new "Hubble2 image" seems *entirely* ok with me as well - seems to be a higher resolution than the "Hubble1 image" (over three times? => 1600x1600/"Hubble2 image" vs 500x500/"Hubble1 image") and nearly the same resolution (only 1/3 less?) of the "MGS image" (at 2400x2400) - also - the "Hubble2 image" seems very popular on Wikipedia (see global usage) - the "Hubble2 image" seems an *excellent* replacement for the "present MGS image" imo - in any case - Enjoy! :) Drbogdan (talk) 13:46, 24 February 2015 (UTC)
 * It's definitely better, but still fuzzy at places and what are the bluish areas (in both Hubble images)? What about the classic by Viking 1, any problems with it? --JorisvS (talk) 16:08, 24 February 2015 (UTC)
 * The "Viking 1 image" seems much better to me than the "MGS image" - but the "Hubble2 image" still seems the best to me atm - (fwiw, User:Joannebogdan rates the images as follows: "Hubble2 image/best" => "MGS image" => Hubble1 image" => "Viking 1 image") - hope this all helps in some way - in any case - Enjoy! :) Drbogdan (talk) 16:31, 24 February 2015 (UTC)
 * So what make the HST2 image better? --JorisvS (talk) 16:38, 24 February 2015 (UTC)
 * To me - the "Hubble2 image" seems more real; the others, less real (more unreal?) - (fwiw - User:Joannebogdan notes => the "Hubble2 image" has a "unique and a distinctive quality - and - is more memorable than the others") - hope this helps - Enjoy! :) Drbogdan (talk) 16:56, 24 February 2015 (UTC)
 * More "real", but why? Is it the colors, that there are ice caps or these bluish clouds (or whatever they are), that the features are less sharp, or something else? --JorisvS (talk) 17:11, 24 February 2015 (UTC)
 * Thanks for the question - Yes - just an overall impression - perhaps the color(s) as noted - or the familiar look (to me) of Mars over the years - more importantly - the "Hubble2 image" seems best to me atm imo - opinions from others are welcome also of course - Thanks again - Enjoy! :) Drbogdan (talk) 17:40, 24 February 2015 (UTC)
 * I have found a different version of the Viking 1 image, with the colors more vivid. What's your impression of that? --JorisvS (talk) 17:54, 24 February 2015 (UTC)
 * The "new Viking 1 image" seems better to me than the "old Viking 1 image" - to me atm - my present rating: "Hubble2 image/best" => "new Viking 1 image" => "old Viking 1 image" => "Hubble1 image" => "MGS image" - please understand, I'm somewhat flexible with all this - I see good material in *all* the images - other opinions welcome of course - Enjoy! :) Drbogdan (talk) 18:17, 24 February 2015 (UTC)

FWIW - a possible "compromise" suggestion *might* be the newly created multiple four-images presentation (or some variant of course) posted above - In any case - Enjoy! :) Drbogdan (talk) 18:57, 24 February 2015 (UTC)
 * I like "Hubble image 2" a lot. It is my first choice, followed by Hubble image 1, followed by both composites, which I disagree with equally. The Rosetta image would be my first choice if not for the copyright issues.


 * The problem with the Viking composite is, like the MGS composite but not as egregiously, it just doesn't accurately represent what Mars looks like from the perspective artificially shown. This is obvious by comparing it to the Hubble images and the (now sadly removed) Rosetta image, which were actually taken from a distant perspective and show much less surface topography, something that I suspect is an effect of the atmosphere. So, to reiterate my initial point, presenting low-altitude images from a distant perspective simply misrepresents how Mars actually looks and is therefore misleading. That is my main problem with such composites, at least of atmospheric bodies. The color of the Viking composite is also a bit wonky, something that is not fixed by tweaking it photoshop. Also, projection artifacts are still present at the edges and poles, as in the MGS composite.


 * I disagree with a 4-image compromise-- the unused images can go elsewhere in the article, and no other astronomical object has a combined lead image since it just isn't aesthetically pleasing. I say we wait for a few more comments, then go with the consensus. I'll post a link to this discussion over at WikiProject Solar System to get some more participation. A2soup (talk) 23:12, 24 February 2015 (UTC)
 * Yes - agreed for my part - no problem whatsoever - should note, however, that a multiple-images lead (in this instance, five images) is on at least one astronomical object article at the following => "Dwarf planet" - in any regards - Enjoy! :) Drbogdan (talk) 00:10, 25 February 2015 (UTC)
 * I meant that there is no article for a particular astronomical object with a combined lead image. Dwarf planet and planet are classes of astronomical objects, so it makes more sense to have a combined image there. Thanks for clarifying the point, though. A2soup (talk) 03:11, 25 February 2015 (UTC)
 * Agreed. Additionally, I think using a combined image makes the individual planet images too small in the infobox to be of use. — Huntster (t @ c) 03:19, 25 February 2015 (UTC)

But why does the Hubble2 image look unsharp—look especially at the south polar region? And why does it end so abruptly at the edges, as if the pixels are not area-averaged of what's actually there? --JorisvS (talk) 09:18, 25 February 2015 (UTC)
 * The abrupt ending at the edges is because the absolutely black background was added in post-processing-- I imagine that the background that was acquired was nowhere near so neat. As for the unsharpness, well, the whole image is kind of unsharp because of the limits of Hubble's resolution. Now I miss the Rosetta image even more; it has neither of these problems :( A2soup (talk) 09:57, 25 February 2015 (UTC)
 * That's exactly the problem I have with the Hubble2 image, especially the latter. It is not of the resolution it pretends to be. And doesn't this contribute to the fuzziness of the surface features? --JorisvS (talk) 14:15, 25 February 2015 (UTC)
 * I do wish that the Hubble images had better resolution, but I still prefer them to low-altitude composites for reasons I have already talked about too much and won't go over again. The Rosetta image is really ideal-- it's beautiful and we all seem to agree on it. The ESA copyright policy states: "Users may not modify, publish, transmit, participate in the transfer or sale of, reproduce, create derivative works from, distribute, perform, display or in any way exploit any of the content, software, material or services, in whole or in part, without obtaining prior written authorization" (emphasis mine). Since Emily Lakdawalla uses OSIRIS images on her blog regularly, and I can't find any contact info for the OSIRIS team directly, I'm going to email her about how we might go about getting permission to use the image. I'll update here with the results. A2soup (talk) 01:12, 26 February 2015 (UTC)
 * Remember, it isn't a matter of getting permission for us to use the images. That's just a matter of fair use, which is what Emily is operating under. We must use freely licensed images because, even if they're not the best of the best, other comparable freely licensed images of Mars exist in spades. Unless ESA specifically releases that image under their CC license, it won't be usable. — Huntster (t @ c) 04:23, 26 February 2015 (UTC)
 * Ah, I understand. I was digging through the copyright policies today (for the first time) and concluded as much. I was holding out hope that perhaps we could we could work something special out given written permission from ESA. You have to wonder what they gain from being so much more restrictive than NASA.
 * (removed comment proposing non-free images here) A2soup (talk) 12:03 am, Today (UTC−6)
 * Sorry, but I've removed those MOM images. I hate to be blunt, but here's a quick tip: never ever ever believe anything relating to copyright on the Planetary.org website. They play ridiculously fast and loose with it, oftentimes ignoring copyright altogether as if they believe all space agencies operate like NASA. For example, this image is from Venera 9, which is covered under then-Soviet/now-Russian copyright law, yet they claim an employee named Ted Stryk owns copyright and has released it under CC-by-nc-sa-3.0. Absolutely absurd and not exactly legal. Back to MOM images, the ISRO has retained copyright over images produced by MOM, just like ESA (normally) does, just like Roscosmos does, just like JAXA does, etc etc. — Huntster (t @ c) 06:19, 26 February 2015 (UTC)
 * Dang, I was so excited to apply my new copyright knowledge too... A2soup (talk) 06:28, 26 February 2015 (UTC)

ADDED NEW MARS IMAGES => added new "Voyager 1 Orbiter - (1980)" images above for possible consideration as follows => File:PlanetMars-VallesMarineris-VikingOrbiter-1980.jpg - and - File:PlanetMars-SyrtisMajor-VikingOrbiter-1980.jpg - may have ok resolution (and ok colors? & related) - Enjoy! :) Drbogdan (talk) 15:24, 25 February 2015 (UTC)


 * BEST Resolution image of *all* images considered seems to be the "Viking 1 Orbiter (1980-A) - Syrtis Major" image (at 41294x4194/8.59mb) - see => File:PlanetMars-SyrtisMajor-VikingOrbiter-1980.jpg - seems this "Viking 1 Orbiter (1980-A) - Syrtis Major" image has even *better resolution* than the ESO Rosetta Mars image (at 2205x2205/1.22mb) - Enjoy! ;) Drbogdan (talk) 17:11, 25 February 2015 (UTC)
 * NEW - HIGHEST Resolution(?) image (6787x6787/57.35mb - TIF-File) (Global Mars; Viking 1 Orbiter; 1998) of *all* images added for possible consideration => File:PIA00198-Mars-Viking1-1998.tif - Enjoy! :) Drbogdan (talk) 21:50, 25 February 2015 (UTC)


 * Comment -- we do not want the highest resolution images / largest file size. (50 MB for a pathetically blurry Viking image?)  Pity the poor readers with slow internet connections.  What we want is the most representative image.  I like the Rosetta image, if we can get it, except that someone "enhanced" the color.  Maybe revert to true color?  (Pending copyright clearance.)  Hubble2 and VikingSyrtis are also lovely.  The problem with the latter, though, is that the atmosphere has been cropped off.  As s.o. commented above, the lead image should clearly show the atmosphere of Mars.


 * The Rosetta img has the additional advantage, besides showing the atmosphere, of clearly differentiating the cratered southern highlands and the dusty plains of the northern lowlands. That's all we could want in a lead img.  If we can't manage the copyright issue, then Hubble2 is the clear choice.  VikingSyrtis should definitely be used in the text, though.  — kwami (talk) 22:05, 25 February 2015 (UTC)
 * Yes - agreed - actual "resolution" on the "1998 TIF-File" image could be better -  also Yes - the "VikingSyrtis" image and/or "Hubble2" image are *entirely* ok with me as well atm - Enjoy! :) Drbogdan (talk) 23:06, 25 February 2015 (UTC)


 * These are my thoughts exactly, kwami. I would only note that the redder version of the Rosetta image is actually closer to true color (red, green, and blue filters) than the browner version, which the ESA website describes as using near-UV, green, and near-IR filters. So the color is actually not "enhanced" (as the uploader stated) so much as taken through different filters that yield a more lifelike result. The Viking Syrtis is definitely the best composite yet, but it's still got the inevitable polar projection artifacts plus some wonky color (black? really?). A2soup (talk) 00:25, 26 February 2015 (UTC)
 * If we could get ESA to change the Rosetta image's copyright, that would be ideal. Note that they have done that with the images of Comet Churyumov–Gerasimenko, which we can now use on Wikipedia. --JorisvS (talk) 13:57, 26 February 2015 (UTC)
 * Yes - agreed - at the moment, the Rosetta copyright re the "Comet Churyumov–Gerasimenko" image seems to refer only to images taken by the Rosetta "NAVCAM" system - and not, unfortunately, by the Rosetta "OSIRIS" system - which seems to have taken the "Rosetta Mars" image - Enjoy! :) Drbogdan (talk) 14:39, 26 February 2015 (UTC)
 * My email to Emily Lakdawalla got passed to someone at the ESA who basically said as much, that OSIRIS images are unlikely to be freely licensed anytime soon. Apparently, ESA doesn't even own the rights to the OSIRIS images, so it's out of their hands. OSIRIS rights belong to the principal investigators for that instrument, so while the Rosetta NAVCAM images (rights belong to ESA) have indeed been freely licensed, OSIRIS images have not. It's a pity. A2soup (talk) 19:25, 26 February 2015 (UTC)


 * That's unfortunate, rules out Rosetta for now. Can we all agree on Hubble2, then, as the most lifelike photo with an atmosphere?  — kwami (talk) 19:47, 26 February 2015 (UTC)
 * The Hubble image has its own set of drawbacks. It is too bad that none of the images seems to have none. --JorisvS (talk) 21:32, 26 February 2015 (UTC)
 * I absolutely agree, it is a shame that the best image is non-free, but that's what we have to work with. For this subject matter, between an image that is lower quality but highly representative of reality, and one that is higher quality but not "real", I'd go with the highly representative one every time. — Huntster (t @ c) 02:31, 27 February 2015 (UTC)
 * ✅ - For now at least - updated the lede image to the Hubble2 image - most seem to agree this image may be the best available at the moment - and sufficiently ok for the Mars article - *entirely* ok with me to rv/mv/ce of course - in any case - hope this helps in some way - Enjoy! :) Drbogdan (talk) 17:22, 27 February 2015 (UTC)

FWIW - Sent an EMail to ESA re the "Rosetta Mars" image as follows:  From: "Dr. Dennis Bogdan"  To: spaceinimages at esa.int, media at esa.int,  scitech.editorial at esa.int Cc: joannebogdan at yahoo.com, drbogdan at comcast.net Date: Thu, 26 Feb 2015 17:23:29 -0500 Subject: QUESTION: Can Copyright Permission Be Granted To Wikipedia To Use A Particular ESA MARS Image In The MARS Wikipedia Article? QUESTION: Is there any possible way to obtain the copyright permission needed for Wikipedia to use a favored ESA Rosetta spacecraft (OSIRIS?) image of the planet MARS in the MARS Wikipedia article?

DETAILS: On behalf of several Wikipedia editors, we would like to use a particular ESA image ( please see => http://www.esa.int/spaceinimages/Images/2007/02/True-colour_image_of_Mars_seen_by_OSIRIS ) of the planet MARS in the MARS Wikipedia article ( at the following => https://en.wikipedia.org/wiki/Mars ) - this particular MARS image ( of several NASA images considered ) ( please see => https://en.wikipedia.org/wiki/Talk:Mars#Lead_image ) is currently favored by Wikipedia editors. Seems we would require copyright permission from ESA that may be compatible with Wikipedia copyright requirements ( please see => https://en.wikipedia.org/wiki/Wikipedia:FAQ/Copyright ).

Thanking you in advance for your reply, Dr. Dennis Bogdan

-- -- May (or may not) receive an answer - but at least an effort was made - Enjoy! :) Drbogdan (talk) 22:46, 26 February 2015 (UTC)
 * Dr Dennis Bogdan * Computer DataPro Consulting
 * drbogdan at comcast.net * drbogdan at yahoo.com
 * http://en.wikipedia.org/wiki/User:Drbogdan
 * http://www.facebook.com/drbogdan
 * http://home.comcast.net/~drbogdan/publications.html

Once Mars had more water than Earth's Arctic ocean
According to research Mars planet had more water than The Earth's Arctic ocean. NASA scientist are wondering why this much water left the planet. Details have been explained here:

http://phys.org/news/2015-03-mars-earth-arctic-ocean.html

-- Mansour JE MansourJE (talk) 07:36, 6 March 2015 (UTC)


 * Yes, that has already been included in the article, along with an explanation that this is by no means absolutely fact. Also,, please add your signature to the end of your post, not the beginning. I've done this for you. Thank you. — Huntster (t @ c) 08:03, 6 March 2015 (UTC)

Measurement units
This is protected so I can't edit it myself. Why is there stuff like "1,155 Pa (1.155 kPa)" in several places in the article? This is insulting the reader's intelligence. Having miles and kilometers makes sense, but Pa and kPa is absolutely ridiculous. Do we write "100 meters (0.1 kilometers)" everywhere on Wikipedia? No, we don't. — Preceding unsigned comment added by 93.136.60.110 (talk) 22:24, 2 April 2015 (UTC)

A few notes on the article
Just thought I'd post a few notes about this article based upon what an ordinary guy might think. I know an article like this can't be dumbed down to a six grader's level, but some things should be more accessible for the non-technical reader.

In the Lede: 1) One thing I would include is the closest distance from Earth as I'm sure that is one of the things people specifically come here to find out; 2) Is it possible to put the equator on the lede photo? Most people who look at it will assume that the equator is right in the middle (along with the Prime Meridian) and not realize that the planet is tilted; 3) I also think it should be noted that the planet is called Mars because the planet is red, which reminded the ancients of blood, which is why the named it after the God of War; 4) As for the point about Olympus Mons, when you state something is the second highest, it instantly raises the question (it does not "beg the question"): what's the highest? (Also, how deep is the lowest point?) 5) While I realize it's customary to give distances using the metric system, would it be out of place to give the Imperial measurements also?

Surface geology: shouldn't "Mya" be defined when first used?

Hydrology: Currently, there is this sentence: "The volume of water ice in the south polar ice cap, if melted, would be sufficient to cover the entire planetary surface to a depth of 11 meters (36 ft)" How is that possible? Does that mean if you stood atop of Olympus Mons you would still be under water? How tall is the ice cap?

Volcanoes: it wouldn't hurt to note the location of Olympus Mons on the small map.

In culture: 1) If you don't put the reason for Mars' name in the lede, then put it here. 2) The paragraph that begins with "Early in December 1900," appears to be a block quote, but because of the placement of the illustration it looks just like another paragraph. Either the picure should be moved or the use of the large quotation marks used to make this clear.

Astronomy on Mars: The caption under the photo reads, "Comet Siding Spring to pass near Mars on October 19, 2014" Can somebody change that to past tense?

And can we get rid of the goofy use of BCE and CE? Shouldn't science be above political correctness? __209.179.1.55 (talk) 01:59, 3 April 2015 (UTC)
 * I think your feedback is very valuable. I too would like to see these points addressed. Thank you. BatteryIncluded (talk) 02:28, 3 April 2015 (UTC)


 * Mostly good points, though adding imperial units to articles can get excessive, and BCE/CE is normal in scientific articles. (Actually, BP may be more common, but changing 1930 to 20 BP would be inappropriate.)  — kwami (talk) 02:32, 3 April 2015 (UTC)
 * This article is not just scientific. The sections using BCE/CE are historical and cultural. I think those are fine the way they are. Scarlettail (talk) 02:55, 3 April 2015 (UTC)

"Atmosphere Scale Height" Earth's atmosphere is closer to 8km than 6km. Also, Mars dust is notably homogenous in the atmosphere with a similar scale height to the gaseous part. — Preceding unsigned comment added by 174.16.78.218 (talk) 00:32, 5 May 2015 (UTC)

Semi-protected edit request on 5 May 2015
Please remove the mean anomaly. Mean anomaly changes constantly. It is unhelpful (and incorrect) to list a static value. — Preceding unsigned comment added by 140.32.16.3 (talk) 14:26, 5 May 2015 (UTC)
 * Wrong, mean anomaly indicates where the body is on its orbit at a specified epoch (time), which does not change. Without an epoch, it is meaningless. But the epoch is specified (J2000). --JorisvS (talk) 19:37, 5 May 2015 (UTC)

Mars gravity vs. Mercury gravity
The gravity of mars is defined as the same as mercury. How is it defined for mercury, the same as mars? That's not a definition — Preceding unsigned comment added by 2602:302:D8C:D9:8CC3:4044:7010:FA37 (talk) 18:49, 6 July 2015 (UTC)
 * It seems that Mars is more massive than Mercury, but Mercury is smaller and denser. By chance, they end up having almost equal surface gravity, which is kind of cool. The surface gravity statistic in both articles is supported by a source. A2soup (talk) 19:04, 6 July 2015 (UTC)


 * The equality of gravity for Mercury and Mars came from the third and fourth sentences in the "Physical characteristics" section. In the Infobox, that area outlined with a rectangle in the upper right hand corner of the article, there is the gravity of Mars listed as 3.711 m/s.  I hope this helps.  - Fartherred (talk) 19:35, 6 July 2015 (UTC)

NASA-TV/ustream (9/28/2015@11:30am/et/usa) - Mars Mystery Solved.
NASA-TV/ustream (Monday, September 28, 2015@11:30am/et/usa) - NASA will detail a "Major Science Finding" about the planet Mars - Enjoy! :) Drbogdan (talk) 00:52, 25 September 2015 (UTC)
 * BRIEF Followup - evidence presented that liquid water may be currently flowing on the planet Mars  (conference videos  and somewhat related Nature (journal) (1979) reference re lifeforms in the hypersaline (and/or brine) water of Don Juan Pond, Antarctica ) - in any case - Enjoy! :) Drbogdan (talk) 18:16, 28 September 2015 (UTC)
 * Pouring cement, honey, molasses, brine, etc. have some water, yet are not water. The flow of brine is not flow of water.  It has a water feature, yes, but for habitability/colonization purposes, solid water ice  is superbly preferred to brine. Cheers, BatteryIncluded (talk) 18:24, 28 September 2015 (UTC)

Salt water
change ((salt water)) to ((Saline water|salt water))
 * ✅, thanks! Gap9551 (talk) 19:16, 27 October 2015 (UTC)

MansourJE (talk) 03:06, 23 December 2015 (UTC)

Volcanoes - addition of Mars Express HRSC images of Olympus Mons
Hi, I recently uploaded https://commons.wikimedia.org/wiki/File:The_complex_caldera_of_Olympus_Mons_on_Mars.jpg and suggest to add it to the volcanoes section ... let me know what you think. Thanks! Mtrova (talk) 17:57, 11 February 2016 (UTC)


 * We already have a very good image in the Volcanoes section that shows off Olympus Mons. I see no reason to add another that will simply clutter things. This isn't a criticism of the image you uploaded, which is nice, just trying to keep the article tidy. — Huntster (t @ c) 20:42, 11 February 2016 (UTC)

NASA Briefings/livestream (March 21 – 22, 2016) – Ceres, Mars, Pluto Results.
NASA Briefings/livestream – Experts to discuss the latest Ceres, Mars, Pluto results (near Houston, TX; March 21 – 22, 2016) - Enjoy! :) Drbogdan (talk) 12:30, 17 March 2016 (UTC)

Interwiki link
Can someone please create an interwiki link to https://mg.wikipedia.org/wiki/Marsa — Preceding unsigned comment added by 2601:14B:8000:8D63:223:69FF:FE00:2E1C (talk) 00:05, 20 March 2016 (UTC)
 * ❌. Instead, I've redirected that page to Mars (fajiry) (it was a fork). --JorisvS (talk) 10:33, 20 March 2016 (UTC)

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Olympus Mons
Please change the current text about Olympus Mons, as it is THE largest known mountain in the solar system, not the second largest. — Preceding unsigned comment added by Kaishaku 1986 (talk • contribs)
 * The thing is, since Dawn has orbited Vesta, it is known that Rheasilvia's central peak is slightly higher, see List of tallest mountains in the Solar System. --JorisvS (talk) 17:52, 18 May 2016 (UTC)

May 12, 2016 New Hubble Mars Image
For the infobox if interested: http://hubblesite.org/newscenter/archive/releases/2016/15/ CuriousMind01 (talk) 12:53, 21 May 2016 (UTC)


 * Nice image, but I think it is still inferior to the image currently in the infobox in terms of overall quality. We had a long discussion about the lead image about a year ago. — Huntster (t @ c) 20:22, 21 May 2016 (UTC)

Tidal lock?
The article contains the following assertion:
 * "7.5 billion years from now. Earth and Mars may become tidally locked with the expanding Sun."

However, I didn't see that mentioned in the attached reference. Part of the problem may be that we don't have full access to the reference work, but the part that was visible didn't seem to mention the possibility. It might help if this statement was backed up by a scholarly study. Praemonitus (talk) 20:43, 27 May 2016 (UTC)

Grand tack hypothesis
Should the third paragraph of the "Surface geology" section cover the Grand tack hypothesis and its likely impact on the accretion of material that formed Mars? Praemonitus (talk) 19:46, 10 June 2016 (UTC)
 * IMO, it seems tangential to Mars' geology. The article is long as it is. My 2 cents. Cheers, BatteryIncluded (talk)
 * Well it explains why the planet is so small, thereby having its present day geological structure and atmosphere. But otherwise yes, I suppose it is tangential. Praemonitus (talk) 13:51, 11 June 2016 (UTC)

Semi-protected edit request on 29 June 2016
The images from the following links should be added to the photos in the "Mars" Article: http://imgur.com/vCubgyA http://imgur.com/KVAnI5S

Blinndsay (talk) 22:59, 29 June 2016 (UTC)
 * Red information icon with gradient background.svg Not done: I don't see any indication that those images are compatibility licensed for use on Wikipedia. Unless they are released by the copyright holder under a compatible license, they cannot be uploaded. —&thinsp;JJMC89&thinsp; (T·C) 02:02, 30 June 2016 (UTC)

The Mars Density Equation
The Density of Mars can be described as an equation of the Form A R^3 + B R + C where R is the Radius in Kilometers, and C is the Density of the Crust, while A is the tri-axial coefficient of compression, and B is the gravitational uni-axial co-efficient of compression. R is the Radius at the tilt angle of a spinning sphere ( approximately 23 degrees 19 minutes and 39.3 seconds of tilt = 23.327 583 333 degrees of tilt. The tilt angle radius gives a slightly better indication of the Volume of an oblate spheroidal planet like Mars, where the Equitorial Radius is greater than the Polar radius. The Tilt Angle Radius = (( 1 X polar Radius) + ( 2.858 093 602 X Equitorial Radius )) / 3.858 093 602. This gives 3391.0161 Km.  The density is then ( 1 + Pi ) X 10^-9 X R^3 +  ( 1 + SQRT 2) X 10^-1 X R + 2941.05 kg/m^3. This gives 161.4942016 + 818.663704 + 2941.05 = 3921.207906 kg/m^3. This is slightly lower density than density listed in the article of 3933.5 +/- 0.4 kg/m^3, but the Radius is slightly higher, and Mass will be 6.404 688 781 E23 is slightly lower, and the surface gravity is slightly higher at 3.71743 m/sec^2 versus 3.711 m/sec^2.  The advantage of the density equation is that it gives a density for the dominate materials that make up the Crust of Mars. That is 2941.05 Kg/m^3 and other materials mixed together still are dominated by the Unit mass of the tholeiitic basalt. In comparison Venus has a Value of C = 2657.05 ( granite and Diorite ), and the Earth and Moon have a value of C = 2900 Kg/m^3 ( >85 % Basalt, and <15 % Granite by volume in the Crust ). The Density Equation is for Rocky Planets, so it doesn't work well on Mercury, or the Gas Giant Planets. In addition it can be used on the ice Planets, but the value of C can be lower than 1000. In conclusion the Rocky Planet Density Equation can be used to determine the density of the crustal materials as well as the overall average density of the Planet, or Satellite of a Planet.63.225.17.34 (talk) 17:11, 3 July 2016 (UTC)
 * Note that any data used in the article needs to satisfy WP:NOR. I.e. it must be based upon reliable sources. Praemonitus (talk) 17:49, 5 July 2016 (UTC)

Move "Moons" section
I feel Moons comes in such an insignificant part of the page. I'm thinking it is worth moving closer to the top of the page. Would it perhaps belong in the Physical Characteristics? Situphobos (talk) 09:41, 8 July 2016 (UTC)
 * Yes, its position below the in-culture things, some even trivial, was ridiculous. I've moved it. --JorisvS (talk) 12:00, 8 July 2016 (UTC)
 * I agree. Its position after the history and culture sections was inappropriate - it clearly belongs nearer the scientific sections, and the new location is much better. Boing! said Zebedee (talk) 12:46, 8 July 2016 (UTC)

Orbital parameters
My understanding was that orbital parameters don't need to be kept highly precise because (1) orbits change due to perturbation, and (2) this is an encyclopedia, not a NASA tracking station. I attempted to rectify this by reverting the edits of W like wiki, but this was reverted without a suitable explanation. It looks like this user has done the same to the other planet wikipages. Praemonitus (talk) 17:39, 4 August 2016 (UTC)


 * Hi Praemonitus, I just filled in the values from the nasa-page. If they are too precise for you: A compromise could be: keep the precise km-value and round the AU-value (but not the old one - the values of some other planets were a bit incorrect before)?! Cheers --W like wiki (talk) 18:02, 4 August 2016 (UTC)


 * The NASA page is based on the JPL data, which uses table 8.10.2 of "Keplerian Elements for Approximate Positions of the Major Planets" by E.M. Standish. For Mars that shows a base a of 1.52371034 in epoch J2000, with a variation of 0.00001847 per century. So yes that's good for what it was like sixteen years ago. Do we need to know it with that much accuracy though? For encyclopedic purposes, a few digits of precision is good enough. I know this has been discussed before. Praemonitus (talk) 19:51, 4 August 2016 (UTC)


 * Your "precise" data may be just an average as the distance varies throughout its orbit. Anyway, this and all other articles you improved with references, do not need AU within nine significant figures. I doubt JPL uses Wikipedia to program their orbiters and landers' firing sequence, so about 3 figures should do fine, thank you.  Cheers, BatteryIncluded (talk) 00:30, 5 August 2016 (UTC)


 * I think W_like_wiki's figures are overly precise, but there's no need to sacrifice a degree of accuracy just because we aren't NASA. I typically go with two decimal places as that conveys a degree of accuracy useful for almost anyone without being overbearingly precise. — Huntster (t @ c) 00:48, 5 August 2016 (UTC)

Request edit on 12 August 2016
Add:

— 2601:183:4000:D57A:E532:F558:2BA1:2602 (talk) 01:33, 12 August 2016 (UTC)


 * No evidence these images are freely licensed, and no reason given for why they would improve the article. Request declined. — Huntster (t @ c) 01:50, 12 August 2016 (UTC)

Absolute Magnitude (H)?
The Mars and remaining solar system body infoboxes should include H, the absolute magnitude. Urhixidur (talk) 13:18, 28 August 2016 (UTC)

One source of H values is this one (IMCCE). Urhixidur (talk) 15:01, 28 August 2016 (UTC)

Wrong numbers
"Mars's cycle of eccentricity is 96,000 Earth years compared to Earth's cycle of 100,000 years.[176] Mars has a much longer cycle of eccentricity with a period of 2.2 million Earth years, and this overshadows the 96,000-year cycle in the eccentricity graphs." Not all of these numbers can be correct. My guess is that the period for the precession of the equinoxes is 2.2 million years (one would expect it to be longer than that of Earth because of the lack of a large moon for Mars) and the 96,000 is for the eccentricity. — Preceding unsigned comment added by 79.255.49.141 (talk) 10:31, 29 September 2016 (UTC)

European Space Agency's Schiaparelli
European Space Agency's Schiaparelli "landed" on Mars on 2016.10.19. Articles from just before the event include http://www.bbc.co.uk/search?q=European%20Space%20Agency%27s%20Schiaparelli and http://www.npr.org/sections/thetwo-way/2016/10/19/498523167/watch-european-probe-will-attempt-to-land-on-mars as well as more recently http://www.telegraph.co.uk/science/2016/10/19/exomars-space-probe-schiaparelli-landing-mars-surface-live/ Kdammers (talk) 19:50, 19 October 2016 (UTC)

Semi-protected edit request on 19 October 2016
The opening statement in the "Hydrology" section is syntactically incorrect. It currently reads : "Liquid water cannot exist on the surface of Mars due to low atmospheric pressure, which is less than 100 times that of Earth's,". This is technically saying the pressure is less than Earth's pressure times 100. What it should be saying is that pressure on Mars is less than 1/100th of Earth, or perhaps pressure is less than 1% of Earth's.

This is more easily seen if you replace phase "less than" with "about". If you were to say "..., which is about 100 times that of Earth's" the flaw is easily visible.

172.4.0.225 (talk) 22:58, 19 October 2016 (UTC)
 * ✅ Thanks! Gap9551 (talk) 23:03, 19 October 2016 (UTC)

Semi-protected edit request on 8 February 2017
Please substitute the link in reference 34 to this one: http://www.nature.com/news/2004/040503/full/news040503-6.html because the current one is dead. IlnarSelimcan (talk) 06:13, 8 February 2017 (UTC)
 * Yes check.svg Done Thank you for replacing the dead link. Gulumeemee (talk) 06:53, 8 February 2017 (UTC)

"Bonneville crater and Spirit rover's lander"
The caption of one of the images says that, but I can't see any lander on it. Maybe the "place where Spirit has landed" or similar was meant instead? — Preceding unsigned comment added by IlnarSelimcan (talk • contribs) 20:44, 22 April 2017 (UTC)

Semi-protected edit request on 1 May 2017
Change "Argument of perihelion" from "286.502" to "336.04084", as per the NASA Space Science Data Coordinated Archive (https://nssdc.gsfc.nasa.gov/planetary/factsheet/marsfact.html), last updated 23th december 2016 and the book Solar System Dynamics, 1999, Murray, C. D. and Dermott, S. F.. 118.211.13.248 (talk) 01:58, 1 May 2017 (UTC)


 * ❌ The number you cite is the longitude of the perihelion, but the number in the infobox is the argument of the perihelion. They are different - see the last bit of Longitude of the periapsis, which states that longitude of perihelion = argument of perihelion + longitude of ascending node. Using your source, longitude of perihelion = 336.04˚ and longitude of AN = 49.58˚, which fit (within 0.04˚) the 286.50˚argument of perihelion in the infobox. All looks good to me, although I can't say I understand the rationale for which parameters are included in the infobox and which are left out. A2soup (talk) 05:33, 1 May 2017 (UTC)

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Irrelevant reference
Reference 24 doesn't say anything about atmospheric pressure on Mars being "6/1000 of Earth's". Someone with edit rights, please do something about it! IlnarSelimcan (talk) 20:25, 22 July 2017 (UTC)
 * Where does it say 6/1000 in the article? I don't see it. Rivertorch   <sup style="color:#FF0066;">FIRE <sub style="color:#0066FF;">WATER   04:15, 23 July 2017 (UTC)
 * It's in the 3rd paragraph of the lead, styled as $6/1000$. I removed ref. 24 which is redundant. The source might be in "Heldmann, Jennifer L.; et al" (currently ref. 25) which I don't have access to.
 * IlnarSelimcan, if you have a specific edit in mind, please feel free to make an edit request on this Talk page. WP:Edit requests explains how to do it. Dlthewave (talk) 12:29, 23 July 2017 (UTC)

Semi-protected edit request on 26 July 2017
In the second paragraph it states: "The rotational period and seasonal cycles of Mars are likewise similar to those of Earth, as is the tilt that produces the seasons." In fact, it is not Mars' tilt that is primarily responsible for creating its seasons. Rather, it's the eccentricity of its orbit (the fact that it moves closer and further from the sun at various times throughout its year) that is primarily responsible for producing its seasons. I might change the current sentence to: "The rotational period and seasonal cycles of Mars are likewise similar to those of Earth. Though its rotational axis is tilted with respect to its orbital plane a similar amount as Earth's, unlike Earth its seasons are primarily caused by its elliptical orbit." Chopachula (talk) 19:01, 26 July 2017 (UTC)
 * Red information icon with gradient background.svg Not done: please provide reliable sources that support the change you want to be made. jd22292 (Jalen D. Folf) (talk) 21:09, 26 July 2017 (UTC)

The 47-year cycle of Mars was observed by the Ancients
The 47-year cycle of Mars: after 47 years - 22 synodic periods of 780 days each - Mars returns to the same position among the stars and is in the same relationship to the Earth and Sun. The ancient Mesopotamians discovered this cycle. 

Mars water discovery
Hello, It is commonly known that evidence of seasonal waterflow or active waterflow was found on Mars near the Curiosity, but the curiosity is not allowed to look. Please try to edit this in to the article. Thank you.

Silica Discovery
Much higher concentration of silica element at some sites over the past last seven months than anywhere else in the last 40 months after landing and silica makes nine tenths of composition of some of the rocks. The high silica was a surprise, the scientist said. And it supports microbal life.

Read more:

http://phys.org/news/2015-12-mars-rover-higher-silica-considerable.html

MansourJE (talk) 06.35, 23 December 2015 (UTC)

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Information seems missing on the distance from earth to mars.
I added a little on the distance. When I get time I may add more if someone doesn't do it first. I think a section should be added to the article on the distance from earth to mars, how it varies, etc. I recommend that in the box on Orbital Characteristics, some stats be added on distance from earth to mars. (PeacePeace (talk) 21:56, 30 September 2017 (UTC))

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Orbital Eccentricity
Can someone have a go at disentangling these two statements:

"Mars's cycle of eccentricity is 96,000 Earth years compared to Earth's cycle of 100,000 years.[176] Mars has a much longer cycle of eccentricity, with a period of 2.2 million Earth years, and this overshadows the 96,000-year cycle in the eccentricity graphs."

Which is it? 96k years or 2.2m years? I am going to guess that both numbers have their uses, but their identification is in error. Or there are two interacting cycles in the fashion of Milankovich cycles and they need to be better distinguished.

50.100.172.151 (talk) 15:37, 2 December 2017 (UTC)
 * There are two cycles superposed on each other as described here. Ruslik_ Zero 16:59, 2 December 2017 (UTC)

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Possibly a contradiction, clarification needed
"In 1840, Mädler combined ten years of observations and drew the first map of Mars".

and then, further, it says

"The first person to draw a map of Mars that displayed any terrain features was the Dutch astronomer Christiaan Huygens.[260]"

I think that these two statements contradict each other, don't you think? IlnarSelimcan (talk) 00:10, 14 December 2017 (UTC)

Semi-protected edit request on 15 December 2017
There is an error in Mars atmosphere text: It says - "The highest atmospheric density on Mars is equal to that found 35 km (22 mi)[141] above Earth's surface." - should be - "The mean atmospheric density on Mars is equal to that found 35 km (22 mi)[141] above Earth's surface." 87.95.32.38 (talk) 17:03, 15 December 2017 (UTC)
 * Red information icon with gradient background.svg Not done: please provide reliable sources that support the change you want to be made. The current text matches the source given. Eggishorn (talk) (contrib) 21:04, 15 December 2017 (UTC)

Is the distance from Mars to the Sun correct?
The distances from Mars to the Sun are listed as: Aphelion 249.2 GM Perihelion 206.7 GM Semi-major axis 227.9392 GM I think those should be in Million kilometers, rather than Billion meters. The entries for Mercury, Venus, Earth, Jupiter and Saturn are listed in Million Kilometers, and the use of GM (Gigameters) for the distances to Mars is confusing. The Planetary Fact Sheet for NASA uses only Million kilometers.

The distances for the pages for Uranus and Pluto are also listed in GM, which I think are misleading. Spacedad2 (talk) 12:05, 8 January 2018 (UTC)


 * Red question icon with gradient background.svg Not done: it's not clear what changes you want to be made. Please mention the specific changes in a "change X to Y" format. ToThAc (talk) 19:27, 8 January 2018 (UTC)


 * I went ahead and handled this. It makes sense to have the article use a more standardised set of units. — Huntster (t @ c) 03:08, 9 January 2018 (UTC)

Climate error
"The summer temperatures in the south can be up to 30 K (30 °C; 54 °F) "

This is obviously wrong. 30C is a hell of a lot hotter than 30K

Aluminium Colours (talk) 03:14, 8 February 2018 (UTC)
 * But it doesn't say that, your quote above removes the key part of the statement - it says: "The summer temperatures in the south can be up to 30 K (30 °C; 54 °F) warmer than...temperatures in the north." (my bold). It's a comparison, and when comparing temparatures the difference (in K) = the difference (in C). I can see why it confused you though, and I don't personally see much need for Kelvin in the comparison at all. It's not wrong though, just maybe unnecessary. -- Begoon 03:25, 8 February 2018 (UTC)
 * For consistency with the way other temperature values in that section are expressed I removed the reference to Kelvin from that statement. -- Begoon 02:06, 9 February 2018 (UTC)
 * Oh crap. I didn't even notice that bit after, I just focused straight on the measurements. Thanks for pointing that out.Aluminium Colours (talk) 12:23, 9 February 2018 (UTC)
 * Heh - don't worry. If you can read it like that then so might others. It does lend itself a bit to misreading in that way. I'm going to reword it to: "The summer temperatures in the south can be warmer than the equivalent summer temperatures in the north by up to 30 C-change." so that nobody else falls into that trap. Thanks for letting us know - this is how articles get improved... -- Begoon 12:41, 9 February 2018 (UTC)

Barely a mention of gravity
Why is Mars gravity only mentioned under the Atmosphere heading, only referenced indirectly? If one is scanning the page, that isn't a likely place in the text where people would look. Could you/someone reference Mars gravity (38% of Earth's) at the top of the article, including it with Mars's most basic features? Thanks! 71.212.148.173 (talk) 20:57, 12 May 2018 (UTC)

Semi-protected edit request on 3 April 2018
can i please edit the page as mars is not the second smallest planet in the solar system. 183.83.222.20 (talk) 11:24, 3 April 2018 (UTC)
 * ❌ because Mars is, in fact, the second-smallest planet in the Solar System (only Mercury is smaller; Pluto is not a planet). Double sharp (talk) 11:26, 3 April 2018 (UTC)
 * Just a comment regarding Pluto no longer being considered a planet: If you look at the planets' and Pluto's orbits from above the plane of the Solar System, and from the side, it's clear that Pluto's is quite different:
 * 1. Pluto's orbit is eccentric to the degree that a portion of it is inside Neptune's orbit.
 * 2. Seen from the side, Pluto's orbit is inclined about 17 degrees from the plane of the Solar System.
 * BMJ-pdx (talk) 18:45, 13 June 2018 (UTC)

Venus is also smaller than mars. — Preceding unsigned comment added by 183.83.222.20 (talk) 11:31, 3 April 2018 (UTC)
 * It is not. Venus is almost as big as Earth; Mars is about half the diameter of Earth. Double sharp (talk) 11:51, 3 April 2018 (UTC)

Synodic period
Mousing over or clicking this label in the box gives the same result as orbital period. — Preceding unsigned comment added by 70.113.85.76 (talk) 23:29, 13 June 2018 (UTC)

Cycle of eccentricity is unclear or incorrect
In the "Orbit and rotation" section, two consecutive sentences about the cycle of eccentricity are inconsistent:

Mars's cycle of eccentricity is 96,000 Earth years compared to Earth's cycle of 100,000 years. Mars has a much longer cycle of eccentricity, with a period of 2.2 million Earth years, and this overshadows the 96,000-year cycle in the eccentricity graphs.

I.e., "96,000 Earth years" vs. "2.2 million Earth years".

This needs clarification or correction.

BMJ-pdx (talk) 18:27, 13 June 2018 (UTC)


 * That's referring to two different cycles of eccentricity that Mars has. I remembered that this was previously discussed at Talk:Mars/Archive 9, but didn't look into it at the time. However, this time I did, and "When Was Mars This Close?" is the only source I can readily find that gives those values; how reliable of a source is it? Lack of information may warrant removal from the article. — Huntster (t @ c) 02:09, 14 June 2018 (UTC)

Table of perihelions/aphelions
I removed the information on closest perihelion and aphelion from the "Orbit and rotation" section, as it was several years old. The next peri/aphelion changes every year, but it is still an interesting bit of information. Do you think it should be in the article? We could make a table with several next peri/aphelions, so it at least doesn't need so many updates. (Or possibly in Orbit of Mars, because it would take too much space here?) --Šedý (talk) 08:55, 21 June 2018 (UTC)
 * No, this is not something needed in the article. As exemplified now, such data will have long periods where it isn't kept updated. — Huntster (t @ c) 02:29, 23 June 2018 (UTC)
 * I think it's a valuable suggestion for the Orbit of Mars article. We should add closest approaches to Earth, and launch windows for Hohmann transfer orbits as well. — JFG talk 20:23, 23 June 2018 (UTC)

Article for deletion discussion - Modern Mars habitability
There is an article at AfD that may interest you. The article is here Modern Mars habitability. Please vote or comment at WP:Articles for deletion/Modern Mars habitability

Robert Walker (talk) 16:20, 18 August 2018 (UTC)

Updated magnitude range
The new values of brightest and faintest apparent magnitude in the 'infobox' were reported in a peer-reviewed journal article that includes updated equations for computing planetary magnitudes. Those formulas will be used to predict magnitudes for future issues of The Astronomical Almanac published by the U.S. Naval Observatory and Her Majesty’s Nautical Almanac Office. The equations were solved at daily intervals over long periods of time in order to determine the magnitude extremes. The paper in Astronomy and Computing can be located at https://doi.org/10.1016/j.ascom.2018.08.002. As noted in the journal article, the apparent brightness of Mars depends on the surface longitude being illuminated by the Sun and being viewed by the observer as well as the longitude of the planet in its orbit around the Sun. The extreme magnitudes reported here take those factors into account. The magnitudes in the section on ‘viewing’ need to be updated. The section also needs to be rewritten since there are misstatements and unsupported statements. For example “Mars usually appears distinctly yellow, orange, or red; the actual color of Mars is closer to butterscotch, and the redness seen is just dust in the planet's atmosphere.” The redness is definitely not just dust in the atmosphere. Many broad areas of the planet's surface are reddish. That is followed by a discussion of pictures taken with a Mars rover which ought to be removed or modified since the section describes observations made from Earth. — Preceding unsigned comment added by Planet photometry (talk • contribs) 16:53, 10 September 2018 (UTC)

Mean Anomaly
Mean longitude

In a previous edit the mean anomaly (a fundamental orbital element) for Mars was dropped from the infobox. The code is still there, but it's missing a value. Please add back in the following: mean_anomaly = $19.373 °$

143.215.30.216 (talk) 22:03, 3 July 2018 (UTC)
 * Red information icon with gradient background.svg Not done: Mars' mean anomaly is 320.45776°. I added this to the infobox. <b style="color:#060">L293D</b> (<b style="color:#000">☎</b> • <b style="color:#000">✎</b>) 22:16, 3 July 2018 (UTC)

The mean anomaly of Mars at J2000.0 is not 320.45776°, I don't know where that number comes from. According to the Mars fact sheet. it should be in the region of 19.4°, as the Longitude of perihelion is 336.04084° and the Mean Longitude is 355.45332° - see Mean longitude - Formulae. All the Mean anomaly values on Wikipedia for the other planets agree with the NASA datasheets within 1%, apart from Mars. Please consider correcting this error. Oobayly (talk) 15:57, 13 October 2018 (UTC)
 * I removed it pending clarification/reliable source specifically for the value which I've been unable to find Galobtter (pingó mió) 16:05, 13 October 2018 (UTC)


 * According to JPL's HORIZONS ephemerides, the Mean Anomaly of Mars at J2000.0 (JD2451545.0) is 19.356°. Interestingly enough, the HORIZON values on the Mars wikipedia page aren't the same as NASA's - they differ between 0.00% and 0.09% - as well as differing from NASA's Mars fact sheet by similar amounts. I'm inclined to use JPL's values... Oobayly (talk) 09:29, 17 October 2018 (UTC)

Infobox wrong info
On Martian average gravity, the infobox gives three different data: 0.376 g, 3.711 m/s² (0.378 g) and 12.18 ft/s² (0.379 g). Only one of them can be correct. Actually, Mars' gravity is 12.211 ft/s² (0.37952948254501 g), so the value given in imperial units is closest, but still wrong. Please correct it! . --212.186.15.191 (talk) 09:21, 27 November 2018 (UTC)
 * I've updated the figure based on a newer source, but it doesn't match yours. If your figure is newer and you can provide a citation, please do so. — Huntster (t @ c) 07:14, 28 November 2018 (UTC)


 * You selected Mars' gravity at the mid-latitudes, that's alright. You removed the contradictions. Thank you. --212.186.15.191 (talk) 09:19, 28 November 2018 (UTC)

Edits to 'viewing' section.
Added the mean apparent magnitude and its standard deviation. Also mentioned that Mars (and Jupiter) are the brightest planets apart from Venus. Removed the unsupported statement that the color of Mars is “butterscotch”. Also removed the incorrect statement that “the redness seen is just dust in the planet’s atmosphere” since there are many large reddish area on the surface which give the planet its color. — Preceding unsigned comment added by Planet photometry (talk • contribs) 16:12, 13 September 2018 (UTC)

True color of mars?
According to this article (https://owlcation.com/stem/True-Color-Photos-of-All-the-Planets) the true color of mars is nothing like the first image on this article (https://en.wikipedia.org/wiki/Mars#/media/File:OSIRIS_Mars_true_color.jpg). Have I misunderstood something? Should we change the image perhaps? — Preceding unsigned comment added by Dlesos (talk • contribs) 14:07, 11 April 2019 (UTC)