Talk:Mars/Archive 6

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The right date of occultation

The right date is 1590 October 13 see here. For further information you can use Solex software of Prof. Aldo Vitagliano or here. --Pracchia-78 (talk) 10:14, 13 March 2009 (UTC)

I checked; you are right. I fixed it. Saros136 (talk) 21:08, 21 March 2009 (UTC)

Currently lacks sources

Hi, this article is currently near the top of the wp:featured articles/Cleanup listing as it is in 5 maintenace categories: Articles needing additional references (Mar 2009), Articles to be expanded (Jan 2009), Articles with unsourced statements (Feb 2008, Aug 2008, Mar 2009), thanks Tom B (talk) 02:03, 17 March 2009 (UTC)

To Do List

The list needs to be updated or removed the things on there dont need to be changed. The surface temp is right according to NASA u can use a temp conversion calc to see the C°. And the first one this message explains the the temperature there "54 °F is correct here, as this is a temperature difference of 30 °C, not an abolute temperature of 30 °C " Kirbyroth (talk) 17:54, 3 April 2009 (UTC)

Removed. Amory (talk) 03:36, 7 April 2009 (UTC)


"The current understanding of planetary habitability—the ability of a world to develop and sustain life — favors planets that have liquid water on their surface. This requires that the orbit of a planet lie within a habitable zone, which for the Sun is currently occupied by Earth. Mars orbits half an astronomical unit beyond this zone and this, along with the planet's thin atmosphere, causes water to freeze on its surface."

This is not a happy passage.

1. The second sentence seems to imply that the sun's' Habital Zone occurs at Earth's location. This is obviously far too narrow a definition. Earth lies within the H-Z but does not define it.

2. The third sentence states that the sun's HZ ends at 95 million miles out (140-45). This is wrong. The HZ has no precise limit but plainly extends far beyond 95 million miles. Arguably it extends to the orbit of Mars and even beyond, given that Martian surface temperature reach well above zero c in summer.

3. The sole cause of Mars lacking liquid water on the surface is its pressure. If the pressure were earthlike then liquid water could exist over large regions of the planet for long periods (given that summer temperatures reach 30 deg c). (talk) 21:27, 7 April 2009 (UTC)dg81.138.163.90 (talk) 21:27, 7 April 2009 (UTC)

I think a lot of the relevant info is covered later on, and in the main article, but agree that this could be tweaked. I must admit to being a bit confused as to where your copied text comes from - it's different from the current revision. How does this sound:

The current understanding of planetary habitability—the ability of a world to develop and sustain EARTH-LIKE lifefavors planets that maintain liquid water on their surface. This requires that the orbit of a planet lie within the circumstellar habitable zone , which for the Sun lies between 0.95 to 1.37 AU[1], an orbit that is currently occupied only (I would STRIKE the word only) by Earth. Although at perihelion Mars' orbit reaches CLOSE TO THE ideal zone, the planet's thin (low-pressure) atmosphere prevents liquid water from existing over large regions for extended periods. The past flow of liquid water, however, demonstrates the planet's potential for habitability. Recent evidence has suggested that any water on the Martian surface would have been too salty and acidic to support terran life.

Emphasis my own. I think it's more correct, especially the last part about terran life.Amory (talk) 00:31, 9 April 2009 (UTC)

I made a quick tweak to the actual article after the poster posted their comment. I have made my comments "IN CAPS" to your post since I thought that would make to easier to compare ideas. -- Kheider (talk) 02:00, 9 April 2009 (UTC)
I don't think the addition of "Earth-like" is necessary. The fragment is defining planetary habitability, which isn't necessarily restricted to a terran definition. It's also partially implied that our understanding is largely biased by "favoring planets that maintain liquid water." The word "only" is kind of important because otherwise, as the anon said, it could imply that the entire zone is occupied by Earth, and that it precludes other objects. The area is pretty much devoid of non-artificial objects, so I think it's acceptable. I'd say "nearly" instead of "close to" RE: Ideal zone. Added citation.Amory (talk) 02:32, 9 April 2009 (UTC)

What does output from JPL Horizons ephemeris (osculating elements) have to do with properly defining a "Habital Zone"? Sounds like someone is just generically defining the current (Epoch 2000) perihelion distance of Mars as the outer edge. What happens in 10,000 years when Mars eccentricity increases to 0.10 and it comes to perihelion at 1.36AU? What happens when Mars has an eccentricity of 0.12 in 200,000 years? (Solex REF) :-)

Since there could be life on the Jupiter's moon Europa, I think the generic "Habital Zone" does infer some kind of Earth-like life walking on the surface, be it humans, frogs, or penguins. The habital zone is NOT fixed. As the Sun gets hotter the zone will migrate outwards. -- Kheider (talk) 03:57, 9 April 2009 (UTC)

The statement as I propose defines planetary habitability as "the ability of a world to develop and sustain life," which avoids the Earth-like bias issue does it not? The issue of Europa is sort of moot given the "liquid water on their surface" sentence. And let's throw "current" between Sun and lies and between Mars' and orbit:

The current understanding of planetary habitability—the ability of a world to develop and sustain life—favors planets that maintain liquid water on their surface. This requires that the orbit of a planet lie within the circumstellar habitable zone, which for the Sun currently lies between 0.95 to 1.37 AU[1], an orbit that is currently occupied only by Earth. Although at perihelion Mars' current orbit nearly reaches the ideal zone, the planet's thin (low-pressure) atmosphere prevents liquid water from existing over large regions for extended periods. The past flow of liquid water, however, demonstrates the planet's potential for habitability. Recent evidence has suggested that any water on the Martian surface would have been too salty and acidic to support terran life.

Amory (talk) 05:47, 9 April 2009 (UTC)

This is featured article and numbers need to be referenced. JPL Horizons has nothing to do with the "Habital Zone" or "planetary habitability" and can NOT be used as a reference for it. Mars biggest problem, in part, may be that it was not larger and more massive so that it could maintain a thicker denser atmosphere with perhaps a stronger magnetic field.
I have changed it to read:

The current understanding of planetary habitability—the ability of a world to develop and sustain life—favors planets that have liquid water on their surface. This requires that the orbit of a planet lie within the habitable zone, which for the Sun currently extends from just beyond Venus to about the semi-major axis of Mars.[1] During perihelion Mars dips inside this region, but the planet's thin (low-pressure) atmosphere prevents liquid water from existing over large regions for extended periods. The past flow of liquid water, however, demonstrates the planet's potential for habitability. Recent evidence has suggested that any water on the Martian surface would have been too salty and acidic to support terran life.

circumstellar habitable zone has a lot of assumed numbers that are simply unreferenced and pulled out of the air. Besides I am confident that a ocean planet with a semi-major axis of 0.90AU should maintain liquid water at the surface.
--Kheider (talk) 18:28, 9 April 2009 (UTC)

Large crater

"in June 2008 three articles published in Nature presented evidence of an enormous impact crater in Mars' northern hemisphere, 10,600 km long by 8,500 km wide, or roughly four times larger than the largest impact crater yet discovered, the South Pole-Aitken basin."

1) I suggest that we add "the South Pole-Aitken basin on Earth's Moon", as context for the non-astronomically-literate.
2) South Pole-Aitken basin says that "it is the second largest known impact crater in the entire Solar System, the largest being the one on Mars' northern hemisphere which is approximately four times as big", in other words that the details of the large Mars crater may be taken as definitely established. Can we determine whether the details of this crater are "established" or "tentative", and synchronize the articles accordingly?
Thanks. -- Writtenonsand (talk) 23:16, 12 April 2009 (UTC)

How about: "...roughly four times larger than the next-largest impact crater discovered, the South Pole-Aitken basin on Earth's Moon." It reads a bit awkward, I'll admit. -- Amory (talk) 04:24, 13 April 2009 (UTC)

Dark Slope Streaks

The Dark Slope Streaks section is in need of a clean-up. The first time I read it, it seemed to state that the streaks are definitely caused by water and/or life. Also, the very short sentences make the section read like it was written as a grade school essay. Dy 162.5 (talk) 04:57, 19 April 2009 (UTC)

There's many, many different kinds of features on Mars. I don't see a reason that dark slope streaks are worth a section over say, lava tubes, polar spots, polar pitting, dust devils or dunes fields. This section smells inappropriate. Bamf (talk) 19:09, 6 May 2009 (UTC)

Suggested content

Under "Mars in fiction" I suggest to add a reference to C.S. Lewis's space trilogy, in particular the first of the three books entitled "Out of the Silent Planet" (1938) in which a voyage to Mars (called "Malacandra") is accomplished by three humans Weston, Devine and Ransom. Ransom is brought there forcefully by Weston and Devine to be handed over to the "sorns", but is able to escape once they are landed and discovers the geology, flora, fauna, and cultures on the red planet and the relationship of earth (called "Thulcandra", the silent planet) with the other planets and forms of life present in the solar system. -- Lwangaman (talk) 22:43, 23 April 2009 (UTC)

Spiral-like striations in Polar Ice Cap

The main article could be improved by adding a link to any mpegs in existence of the seasonal formation and evaporation (sublimation?) of the polar ice cap. The main article doesn't explicitly say which orbiters are in polar orbits to make this sort of thing possible, but I'll assume that at least one of them crosses over the pole regularly. Why does the polar ice cap show spiral deposit patterns? Is this the result of seasonal winds that drive the CO2 into the patterns that are observed? (talk) 04:11, 30 April 2009 (UTC)

Visibility from . . . Ganymede?

The main article says that Mars is visible with the naked eye, to an observer on the Earth.

If there were an observer as far away as one of the satellites of Jupiter, would Mars still be visible with the naked eye? (talk) 02:05, 6 May 2009 (UTC)

Probably not. Jupiter is much farther from Mars than Earth is. It would probably appear slightly larger than Jupiter's Galilean moons do from Earth. Cadwaladr (talk) 19:10, 9 May 2009 (UTC)

But wouldn't the Galilean moons be visible from Earth, if not for their proximity to Jupiter? Looking at their articles, their apparent magnitude at opposition is all brighter than 6. --Patteroast (talk) 21:03, 9 May 2009 (UTC)
Hmm, I hadn't thought of that. I've only seen them with a telescope, so I didn't figure they could be seen without it. Cadwaladr (talk) 21:21, 9 May 2009 (UTC)
Yes, the Galiean moons can be seen from Earth with naked eye. Read it in a book by some author name like Shaeffer. I'll try to look it up in the library tomorrow. Saros136 (talk) 03:19, 11 May 2009 (UTC)
I believe it is Fred Schaaf in Seeing the Sky: 100 Projects, Activities, and Explorations in Astronomy Saros136 (talk) 03:29, 11 May 2009 (UTC)
And as for the mangitude of Mars from Jupiter's moons. Yes the magnitude is often low enough for the naked eye. I used SOLEX 10.0. Gave Earth the semimajor axis of Jupiter, and vice versa. Between now and 2031, the magnitude of Mars from this fake Earth dropped as low as 3.3. The program calculated 2000 dates at four-day intervals.In 1723, the magnitude was less than 6.1. Saros136 (talk) 03:56, 11 May 2009 (UTC)
But on the other hand, the semidiameter would never be more than 1.34 seconds. Saros136 (talk) 04:03, 11 May 2009 (UTC)
I checked and found Schaaf's statement in his The 50 best sights in astronomy and how to see them. He says he saw two of the moons naked-eye. Saros136 (talk) 20:20, 13 May 2009 (UTC)

Visibility of the Earth's Moon from Mars?

Is it possible for an observer on Mars to see the Earth's Moon? I'm not exactly sure about the scales involved. Would it depend on the illumination of the Moon by the Sun, and how close Mars was to Earth? At what point would a telescope be an absolute necessity? (talk) 02:28, 18 May 2009 (UTC)

i need info for a report

Please help by adding useful information.

Thank you.

DjgrungeQwerty (talk) 12:52, 27 May 2009 (UTC)

Got just the thing for you. Follow this link. Cheers, --PLUMBAGO 15:42, 27 May 2009 (UTC)

Habitable zone

Should we expand the habitable zone from Venus to just beyond Mars? See ESO A planet in the habitable zone. I have always thought the wiki zone was too Earth-Human biased. -- Kheider (talk) 00:55, 15 June 2009 (UTC)

Temperature Update

"The summer temperatures in the south can reach up to 30 °C (54 °F) warmer than the equivalent summer temperatures in the north" needs to be updated. 30 degrees Celsius is not 54 degrees Fahrenheit.

Krohn211 (talk) 18:22, 21 May 2009 (UTC)

The text isn't saying that a temperature of 30°C = 54°F (= 303 K) , it's saying that a change in temperature of 30°C is equivalent to a change of 54°F. I think that's correct (isn't 1°F = 5/9°C?). --PLUMBAGO 19:20, 21 May 2009 (UTC)

54°F = 12°C 30°C = 86°F (talk) 22:24, 15 July 2009 (UTC)

Lightning on Mars?

Is it possible for static electricty to develop in the atmosphere on Mars, and have there ever been any discharges of static electricity observed by any of the orbiters? In other words, has there been any lightning observed in the last few years? How rare must an electrical discharge of that kind be? (talk) 01:27, 15 June 2009 (UTC)

how many km. from Earth ?

I find no info about this--Ezzex (talk) 17:59, 20 July 2009 (UTC)

Mars distance from the Earth varies a lot since sometimes they are on the same side of the Sun and at other times the are on opposite sides of the Sun. But during closest aproaches (Mars#2003_closest_approach) Mars is about 55.7 million from the Earth. -- Kheider (talk) 19:15, 20 July 2009 (UTC)

Yearly rumor

I have more info about Mars from Link --Angeldeb82 (talk) 18:25, 22 July 2009 (UTC)
That "close approach / big as the full moon" rumor goes around every year... -- Kheider (talk) 18:55, 22 July 2009 (UTC)
Right now Mars is in the morning sky near Venus (which is currently 120x brighter than Mars). Mars is above both Venus and Aldebaran (a red giant star that is 44x times the diameter of the Sun), but Mars is below the Pleiades (star cluster). -- Kheider (talk) 19:10, 22 July 2009 (UTC)

Incorrect photo

The photo shown on the Mars Wiki page is incorrect. It shows the Martian atmosphere as blue.

The correct color is orange. The first Mars color photo from Viking 1 was released with the sky shown as blue, the wrong color. —Preceding unsigned comment added by (talk) 22:46, 9 June 2009 (UTC)

No, the blue color is the correct one. Take any image processing software and see for yourself how they at NASA has been fooling the world for all these years. Tell me, how ice can be pink? (talk) 16:49, 20 July 2009 (UTC)

Mars sky is kind of the opposite of the Earth's. On Mars the sky is pinkish during the day, but near sunrise/sunset the sky near the Sun can be blue. Your pink ice is probably just dirty ice covered in red dust. -- Kheider (talk) 17:47, 20 July 2009 (UTC)
More precisely, the sky is pinkish or orange near the horizon, and fades to near black at the zenith (directly overhead). There are two reasons for this. First, the reddish color comes from dust particles. Since there is no precipitation or moisture to wash the dust out of the sky, the finest particles are continually blown off the surface by the wind and are more or less suspended in the air. Second, the layer of air is much thinner than on Earth, so looking upward you are looking through very little atmosphere (and little dust) between you and the blackness of space; thus the overhead is both darker and bluer. Nevertheless, photos that have been properly calibrated to be close to what the naked eye would see—well, the space-suited eye, anyway—tend to be very blandly reddish-orange. Many photos that NASA releases enhance color differences to make them more interesting and informative. The image in question is of "Big Joe," a rock near Viking 2. The bluish-gray spots on its sides would probably only appear slightly less red to the eye. The above-mentioned effect of bluer sky toward the zenith is also exaggerated in this photo. Probably the original photo was released with some kind of commentary calling it enhanced and explaining why. —Preceding unsigned comment added by Illexsquid (talkcontribs) 08:20, 13 August 2009 (UTC)

Pink Ice?

Please explain why does Mars has a pink polar ice cap as seen on the picture in the article on Climate? —Preceding unsigned comment added by (talk) 23:48, 19 July 2009 (UTC)

The pinkish color is partly due to dust from the atmosphere settling on the ice; this is a constant process so the ice would be dusty throughout. However, the photo has probably also been processed to be color-enhanced and this would greatly exaggerate the color of the ice caps. Illexsquid (talk) 08:26, 13 August 2009 (UTC)

Stupid question, but...

Is it possible to breathe on Mars? —Preceding unsigned comment added by (talk) 06:22, 28 July 2009 (UTC)

I believe the short answer is no. The air pressure is 1/100th of Earth. Jusdafax (talk) 06:26, 4 August 2009 (UTC)

  • And also the atmosphere is 96% carbon dioxide and only 0.2% oxygen. In the unlikely event that decompression or the surface temperature didn't kill you, you'd succumb to hypercapnia or hypoxia fairly quickly. --GW 08:22, 4 August 2009 (UTC)
Adding to the fun, Mars is hyperarid and the dust reacts with moisture, so that the water in your lungs and throat would be quickly sucked out chemically, even as it boiled in the low pressure and froze in the low temperature. Good times.... Illexsquid (talk) 08:31, 13 August 2009 (UTC)

Good question. Does anyone know (1) the lowest pressure to which a human body can be taken in a hyperbaric chamber while still remaining functional/conscious for a short period of time, and, (2) what the highest air pressure found on Mars actually is (at the equator during summer say at the lowest point of an immensely deep canyon)...? I don't think "hyperarid" -- whatever that is -- would immediately result in "chemical [dehydration]" (whatever that is?). To refine the question of this post, is it conceivable persons could survive for a a few minutes or so at the bottom of a deep Martian canyon at noon in the summer (when temperatures briefly reach 60 F) after super-saturating their blood with oxygen and decompressing? Couldn't persons (try) to hold their breath for a minute or so while running in such conditions to an emergency-station oxygen mask? Unilke carbon monoxide, carbon dioxide will flush from a person's bloodstream relatively quickly once they are breathing oxygen again, right? (This is just for a scene I'm writing...any thoughts wold be appreciated, thanks.) —Preceding unsigned comment added by Ericmachmer (talkcontribs) 03:30, 5 September 2009 (UTC)

Gauquelins' astrological research

What about a mention of the Gauquelins' "Mars effect"? Maybe not a full description here, but there could be a brief mention and a link to the "Gauquelin" page. Wombat140 (talk) 16:41, 1 August 2009 (UTC)

For some reason that reminds me of the correlation between pirates and global warming. :-) At first glance the idea seems dubious and the article doesn't seem properly cited or neutral. Still, the topic appears notable and has received a modicum of coverage in journals. It probably belongs in the culture section.—RJH (talk) 19:10, 13 August 2009 (UTC)
The proposed "Mars effect" is about astrology, not about Mars. Link it up to Astrology and some more. ... said: Rursus (mbork³) 19:02, 2 September 2009 (UTC)

Wrong Max Temperature for Mars

Max temperature should be +35 not -5.

The maximum temperature given in this article for Mars is -5 Celsius. However, NASA’s Spirit rover has recorded 35 Celsius or 95 Fahrenheit on many occasions, using its Left Front Hazcam.

Quoting the NASA jpl webpage -

"Temperatures in the shade for Spirit ranged from highs of about 35 degrees C. (95 degrees F.) in summer to lows of -90 degrees C. (-130 degrees F.) in winter."

Daytime temperatures at Opportunity and Spirit's locations were expected to range between -40 and +40 celsius as these were the temperatures both the rovers were designed to operate in. Temperatures could have reached in excess of +40 Celsius, even in the shade, during the southern hemisphere's summer, but for the cooling affect on daytime temperatures caused by huge dust storms blocking out the sun.

The very first soil temperature Spirit took was recorded at +5 Celsius.

The Min temperature given for Mars also does not look correct, far too high. I have not researched this through looking at NASA's websites but I have read in many other websites it would fall to around -120 celsius during the southern hemisphere's winter, near the pole. For example see -

I think the Max of -5 and Min of -87 Celsius, given in this article, is only accurate for a very average location on a very average day on Mars and is nowhere near the extreme range for the whole planet. The extreme surface temperatures on Mars possibly range between -140 Celsius, at the South Pole and +40 Celsius near Mars's tropic of Capricorn, around Spirit's latitude, because Mars's closest approach to the sun is during the Southern Hemisphere's late spring and coincides with Spirit's location crossing the equator and having near maximum daylight hours. The average temperature on Mars is probably correct at around -50 Celsius.—Preceding unsigned comment added by (talk) 04:48, 26 August 2009 (UTC)

Problematic section: Evolution

The section Evolution is very problematic, it seems to be full of speculations that aren't cited, and that in my estimate, seems to deviate too much from what I know the research has proposed. It was created 29 January 2009, and removed in 28 June 2009 and then immediatelly reverted back by the author of it for the very bad reason that "it's even more inappropriate for an FA article to lack such basic info"! Now if that is inappropriate, or merely a lack of citeable sources, then consider WP:OR! I propose the author of said section go find some appropriate sources soon, or the section should be moved from the article to this talk page. ... said: Rursus (mbork³) 19:19, 2 September 2009 (UTC)

Asteroid kill magnetic field?

Not, time now, but searching for mayhap sources to section Evolution (living on borrowed time and too tolerant editors!), I found a few links:

A diversity of pretty reliable sources. No satellite explanation for the northern hemisphere, however, and no similar fringe theories. ... said: Rursus (mbork³) 20:07, 2 September 2009 (UTC)

Says Who?

Since this article is semi-protected, I'll let you all handle this, but the second to the last paragraph of the section Viewing: Martian 'Canals' is without citation or sources. It read:

It was not until spacecraft visited the planet during NASA's Mariner missions in the 1960s that these myths were dispelled. The results of the Viking life-detection experiments started an intermission in which the hypothesis of a hostile, dead planet was generally accepted.

Says who?

Additionally, what is meant by "intermission," cause there has been no real "intermission." Missions to and reconnaissance of mars has been pretty continuous from the 1970's on: multiple probes in the seventies and orbiters active until 1982, the two 1988 Soviet Phobos Probes, the 1992 failed Mars Observer, the successful Global Survey or in 1996 (operational until 2006), 1997 Pathfinder, and the 2007 Phoenix Lander, along with many future missions planned, such as the 2011 Mars Science Laboratory.

I suspect "intermission" here means those who scientifically viewed Mars as a potential abode of life, rather than an intermission in exploration. But yes your point is taken; citations are definitely needed for that viewpoint.[2]RJH (talk) 22:19, 5 November 2009 (UTC)

Finally, the Viking Life-Detection experiments did not confirm life on Mars, but they certainly didn't settle the question; mostly, the data was viewed as inconclusive. If anything, it has pressed many Mars enthusiasts to ask for more tests to confirm the question of life on Mars. From this very article:

Evidence suggests that the planet was once significantly more habitable than it is today, but whether living organisms ever existed there is still unclear. The Viking probes of the mid-1970s carried experiments designed to detect microorganisms in Martian soil at their respective landing sites, and had some apparently positive results, including a temporary increase of CO2 production on exposure to water and nutrients. However this sign of life was later disputed by many scientists, resulting in a continuing debate, with NASA scientist Gilbert Levin asserting that Viking may have found life. A re-analysis of the now 30-year-old Viking data, in light of modern knowledge of extremophile forms of life, has suggested that the Viking tests were also not sophisticated enough to detect these forms of life. The tests may even have killed a (hypothetical) life form.[89] Tests conducted by the Phoenix Mars Lander have shown that the soil has a very alkaline pH and it contains magnesium, sodium, potassium and chloride.[90] The soil nutrients may be able to support life, but life would still have to be shielded from the intense ultraviolet light.

-- (talk) 18:52, 21 October 2009 (UTC)

30 degrees celsius is 86 degrees fahrenheit

in the climate section, 30 degrees celsius is listed as being 54 degrees fahrenheit. This is incorrect. It should be 86 degrees fahrenheit.

See Talk:Mars/Archive_3#Climate_2 -- Kheider (talk) 08:33, 23 September 2009 (UTC)

Cite error: There are <ref> tags on this page, but the references will not show without a {{reflist}} template (see the help page).