Planet Four Talk

Mars and The Solar System - For Beginners (2).

  • Kitharode by Kitharode moderator

    For any future martian explorers who pass by this way: In the ‘Beginners 1’ part of our investigations we are looking at Mars and its place in the solar system. We’re talking orbits, distances, interactions with other planets, and anything else we can cram in there to do with ‘the bigger picture’.

    What I’d like to try and do here is to share some of the things I’ve ‘discovered’ about Mars since I first arrived here. My plan (if you can call it that) is to have a look at Mars from a distance and take a first look at its general characteristics. Most of this will be familiar to you all.

    We could then take a broad view of some of the zones, areas, belts and other bulk features of the martian surface. Some of these I already knew about, but others are completely new to me and what I have learnt about these zones has completely revolutionised my view of Mars.

    We might draw a circle and a few lines here and there, but it’ll be mainly chitchat I think. I’m also hoping it’ll help you to locate some of the objects you are classifying even if all that means is;

    Well, at least it won’t be there then!!

    If you didn’t pick up a Mars Fact Sheet on the other thread, here it is again:

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

    You can use it to put some numbers to the Earth and Mars comparison image below. Notice that the image shows the different axial tilts of Earth and Mars, which of course WE already know about. 😉

    http://www-k12.atmos.washington.edu/k12/mars/graphics/Mars_Earth.new.gif

    There are zillions of images of Mars available, but because we’re heading for the Southern territories when we land I thought this one was nice;

    http://www.planetsforkids.org/upload/-mars_1.jpg (because I’m a big kid)

    Earth and Mars are very different from each other for a number of reasons. Some of these you will already know. However, with the materials you have to hand from our discussions so far you should be able to add a few more items to your list, as well as getting a feel for the ‘how and why’ these differences exist. If you ‘discover’ something for yourself, please post it here to help future martian visitors understand Planet Four.

    I’ll probably be asking you to draw a circle and a few lines next (when I’ve worked out where they go!) so if you’ve got any ideas or questions you want to start off with, now’s your chance. Don’t wait too long or you’ll never get a word in edgeways. ** 😮 **

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  • Kitharode by Kitharode moderator

    In case we do any martian rock collecting on Mars, I've asked a silliy question to make sure we'll be able to take them home with us. It's a genuine (if silly) question and I think you could all help me out. Cheers.

    http://talk.planetfour.org/#/boards/BPF0000006/discussions/DPF0000csb

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  • Kitharode by Kitharode moderator

    To help with your martian surface studies when you mark your fans and blobs, try this from JellyMonster (JM) who has produced a great side-by-side comparison of images that you'll see here.

    http://the-orangery.weebly.com/mars-1.html Great work from the 'Image Wizard', eh?

    PS. Need a similar nickname for wassock's magic touch ... any ideas? http://talk.planetfour.org/#/boards/BPF0000009/discussions/DPF0000cvn?page=1&comment_id=515634032dda9003c1000017

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  • Kitharode by Kitharode moderator

    From Wikipedia: Geography (from Greek γεωγραφία, geographia, lit. "earth description". A literal translation would be "to describe or write about the Earth".

    So why do we do geography on Mars? Shouldn't it be Marsography? Or something ... ? * 😄 *

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  • angi60 by angi60 in response to Kitharode's comment.

    Hi Kitharode. Yes, that's a point. Are you hitting me with the Greek again?!

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  • Kitharode by Kitharode moderator

    Looked it up in my dictionary as well - Geogony, geography, geographer, geographical only refers to Earth. Nice 'daft' question though I thought. Maybe I've invented a new word. 😉

    I'm with an astronomer at the minute, so any tricky questions you've got, now would be a good time to ask.... (I'm free in about half an hour(ish).

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  • angi60 by angi60 in response to Kitharode's comment.

    Hope your enjoying the astronomer's company 😉 I'm tongue tied - I can't think of a question! Who'd have thought it, me tongue-tied!

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  • lonelystar by lonelystar

    Kitharode- maybe Aresography?

    Wasn't Ares the Greek god of war and Mars the Roman counterpart? I believe that most of planets are named after the Roman Gods apart from Uranus, Pluto and Earth. (I may be wrong here 😉 ) As all Earth study words (geography, geology etc) all start with a Greek prefix, would our Martian surface studies go with that or stick with the Latin?
    Geo is taken from the Greek word γη or γαια meaning "earth" so Geo- is a prefix for many words dealing in some way with the earth. How about an Ares prefix? Just wondered! Do you fancy Marsography or Aresography? (Hey, mod set up a vote!)

    (I think that Uranus and Pluto are named after Greek gods and that Earth is from a Germanic language.)

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  • Kitharode by Kitharode moderator

    Well that pretty well sums it up for me and I'm sure you've got your pantheon in order. James Lovelock's Gaia Theories are another earth example. Looks like you've already started a poll so I'm voting for Marsography, because if you spell Arseography wrong ... well, need I say more? 😉

    Nice post Lonely star - Thanks.

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  • angi60 by angi60

    I vote for Marsography too - it's easier to say. Sorry Lonely Star- good suggestion though 😃

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  • Kitharode by Kitharode moderator

    So, Marsography 2 - Aresography 1 (undecided). Come on you martians !!

    Before I arrived on Mars I imagined the permanent south polar cap to be much bigger than it is and also much thinner than it is. I'd imagined it was the polar cap that grew in winter and retreated in summer. I'd also thought that the ice cover grew over a much larger area. Upon first meeting the 'spiders' I thought they were scattered all over the southern hemisphere and that yardangs were either scattered in amongst them or perhaps confined to areas nearer the pole. How wrong I was.

    The southern polar cap is relatively small with a diameter of about 350km, but it is 3km thick. It does not sit directly on the south pole but is off-centred because snowfall varies either side of the pole. The icelayer that forms in winter covers the ice cap and it is this icelayer that extends and retreats over the martian year. Spiders are not scattered all over the south, they are to be found within a zone around the pole, between latitudes 84 degS and 75 degS. Yardangs are generally found in equatorial regions.

    You might like to add some bulk numbers to a drawing of Mars. A circle with poles (90 deg) and equator (0 deg) is all you need to begin with. In the southern hemisphere, divide the circumference of one quadrant into three, to give you 3 x 30 deg steps, then divide each of these into three to give you 9 x 10 deg steps from pole to equator. From there you can mark the following:

    South polar cap and environs, 90 - 84 degS approximately 405,416 sq.km.

    Zone of spider formation, 84 - 75 degS approximately 2,069,757 sq.km.

    The equatorial regions, 75 - 0 degS approximately 69,987,647 sq.km.

    This gives a total surface area for the southern hemisphere of 72,462,820 sq.km. (Mars total ~144,000,000 sq.km)

    Hopefully when you've drawn in a few lines and added the numbers it'll give you a better feel for the 'marsography' of the red planet.

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  • angi60 by angi60 in response to Kitharode's comment.

    So is it Marsology for the Geology?!

    Good lot of research! They're vast areas. It's a bit late for me to be drawing now - I'll have a go tomorrow though.

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  • JellyMonster by JellyMonster

    Kitharode, terrific stuff as usual but I do have a couple of questions.

    Are you saying southern polar cap is 3km thick with CO2 ice?

    You have also said that yardangs are generally found in equatorial regions. So would you say that they are not uncommon in polar regions (as we have seen many images of them).

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  • mschwamb by mschwamb scientist, translator in response to Kitharode's comment.

    Great stuff. Do you have references for this?
    Cheers,
    ~Meg

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  • Kitharode by Kitharode moderator

    Thanks all. For now I'm only saying that the southern ice cap is 3km thick. It is not all CO2 ice. Lots of water ice involved but haven't yet got a clear picture of how much or where it is. Seem to remember that the water ice is somewhat 'round the edge' of the cap, but as I said it's not something I've sorted yet.

    The yardangs have become a problem. I've reread the blog post and this suggests that yardangs are near (around?) the polar cap, which is what I first thought when we were talking katabatic winds and 3km slopes. Being unable to track down the article that says "yardangs are generally found in equatorial regions" I'm wondering if I've mixed up an article about desert yardangs on Earth with our martian counterparts. Could well be, so take with a pinch of salt for now (easy on the vinegar)!

    Anya provided the spiderland latitudes (75 - 84S) and the sq.km numbers I worked out myself - after I'd got a teacher to show me the equations. 😛

    Angie60: I like Marsology, goes with Marsography nicely. I'd also like to be a Marsographist rather than Marsographer. * 😃 *

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  • Kitharode by Kitharode moderator

    ... and assuming my maths teacher gave me the right equations and my finger slippeth not on the calculator, then;

    Surface area of the icelayer extending to 60 degS = 9,708,652 sq.km. (Australia, 7,692,024 sq.km.)

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  • Kitharode by Kitharode moderator

    Wiley Online Library...A. Wesley Ward. (Article first published online: 28 DEC 2012)

    "Yardangs are streamlined erosional wind forms, similar in form to inverted boat hulls, that in terrestrial deserts range from meters to kilometers in length. On Mars the best examples are seen in the equatorial region".

    My bold emphasis. Don't have link, but most of abstract is in first post here: http://talk.planetfour.org/#/boards/BPF0000008/discussions/DPF0000cce (Yardangs - More Interesting Than I First Thought)

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  • angi60 by angi60 in response to Kitharode's comment.

    So what's the difference between a Marsographer and a Marsographist? (Sounds like the start of a joke, doesn't it?) I did my homework and drew the regions. It hadn't struck me until then that where spiders form is a relatively narrow band.

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  • Kitharode by Kitharode moderator in response to angi60's comment.

    Either the difference is one ends with -pher and the other with -phist or there is no difference because neither of them exist. 😉

    Yes indeed, spiderland is a fairly narrow band and more southerly than I expected. I've also been reading that the main activity occurs more on one side of the pole in an area called the 'Cryptic Region'. Haven't got the details here (they're on wikipedia) but here's an image: http://www.esa.int/var/esa/storage/images/esa_multimedia/images/2006/10/cryptic_region_on_martian_south_polar_cap/10189702-2-eng-GB/Cryptic_region_on_Martian_south_polar_cap_medium.jpg

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  • angi60 by angi60 in response to Kitharode's comment.

    Well, yes I know that - I was just joking 😃

    All of this stuff can seem cryptic to me! Cool image, thanks 😃

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  • Kitharode by Kitharode moderator

    Interesting snippet from one of the HiRise science papers which boils down to:

    The amount of dust from the fans and blobs you are marking adds up to 4 x 10^13 kg moved in the seasonal cycle every year. This is equivalent to 100 times the mass of dust in a global dust storm.

    In citizen science language this means spiders spit out 40 BILLION TONNES of dust per season in the southern cryptic region. Wow.

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  • Kitharode by Kitharode moderator

    Weekly weather reports from the 'martian met office'. Fabulous site with great views of the southern polar cap going round the pole due to its off-centre location. Look down the page for historical weather. Amazing....

    http://www.msss.com/msss_images/latest_weather.html

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  • angi60 by angi60

    That's an AMAZING amount of dust! I loved the weather videos. They certainly illustrate the lob-sided polar cap well. I notice the southern polar cap had a slightly white Christmas in 2012!!

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  • wassock by wassock moderator

    Ah but is that kg on earth or on mars?

    Next sum required is how much CO2 is needed to carry the dust.

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  • Kitharode by Kitharode moderator in response to wassock's comment.

    Wassock, you stole the question right out of my mind. Am trying to see if it's been made clear in the text whether we're talking earth or martian kg's. Same applies to mass/weight figures for ice/m3 etc. There's a lot to read and sometimes I rather glaze over when I meet some of the text. Having said that, it sounds like a lot of dust wherever you measure it.

    It's on the joblist, along with the other 10 million or so details we're looking for !! 😉

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  • lonelystar by lonelystar in response to Kitharode's comment.

    Kith, Wassock (hello there, nice to meet you).
    Arm waving physics teacher here getting over excited and jumping around the lab about the difference between mass and weight.

    Mass- measured in kilograms- is the same where ever you go in the universe (although I believe that the laws of physics break down in black holes 😃 ). A kg on Mars is the same as a kg on Earth. So Kith my dear, it should not matter if we are talking Earth or Martian (Aresian) kg, they are the same!

    Weight- a force measured in Newtons- depends on the strength of gravity. Thus a kg on Mars weighs less than a kg on Earth. Good way to lose weight after all those Easter eggs- go to Mars 😃

    For the mathematically minded the equation linking mass and weight is....... Weight (N) = mass (kg) * gravity (N/kg)

    I am therefore assuming that the 40 billion tonnes that Kith mentioned earlier is the mass of material and would have the same mass on Earth, or Jupiter or wherever, but would be much heavier/ weighty on Earth (and Jupiter).

    It would be nice to know how they estimated the mass of the dust/ice/rock. Is it done using density and volume? How does the lower gravity and atmospheric pressure on Mars affect the density of the ice compared to ice formed on Earth?

    So, lesson and homework. Over to you Kith.

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  • wassock by wassock moderator

    Hi lonely star welcome to the party. It's a proper 40 billion too! There's a link to the paper the estimate comes from further up the thread. The dust inthe fans is assumed to be colloidal . Is your fluid dynamics up to how much CO2 is needed to move a ton? There's a value of 3g a cm3 somewhere for the density

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  • Kitharode by Kitharode moderator

    (Kitharode throws ball back to Lonelystar.....)

    Here's the science paper - Good Luck. https://docs.google.com/viewer?a=v&q=cache:_iS_YyD3yfYJ:www.lpl.arizona.edu/~shane/publications/hansen_etal_icarus_2010.pdf+&hl=en&gl=uk&pid=bl&srcid=ADGEESh5DV0zqdOdYmDBG17CUAp5ZG-wwuBIEYPt7jQOBgciXYD6ZuwWqfdj0OP0vZG7qfu3ufb2o5UFK8p3x0OGdLyXl8z42scVLKqzJ5DBN8jlYFBQYIT0AGtuWTn61jd46ItPFa0e&sig=AHIEtbS9i4ku-URXDEMaBiAqbeIMXx5j1A

    Fluid dynamics for beginners - this should be good. Lonelystar? * 😛 *

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  • lonelystar by lonelystar

    Hmmmm, might leave that one for my students for now. I'll get back to you on that. 😄

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