A lunar mountain's eternally sunny disposition

By Phil Plait | September 25, 2008 8:53 pm

At the south pole of the Moon is a remarkable place. Shackleton crater, 19 km across, sits almost exactly at the equivalent of 90 degrees south latitude on the Moon. Parts of its rim stick up so high that, for them, the sun never sets. It’s up over the horizon (though very low) all day, every day.

AMIE map of the lunar mountain that always has a sunny disposition
The sunny mountain is on the right.

Near that crater is a peak that shares this characteristic. If you camped at the apex — better bring some air and a refrigerator — it would never be night.

We’ve seen these features due to many probes orbiting the Moon and taking data, But now, for the first time, we have a 3D map of that area thanks to the AMIE (Advanced Moon micro-Imager Experiment) camera on SMART-1, a European lunar orbiter (the name comes from it being the first of the series of Small Missions for Advanced Research in Technology). AMIE wasn’t designed as a stereo camera, so what scientists did was to map the reflectivity of the moonscape and then, using the Sun angle, determine the slope of the area. Each pixel on the camera maps to an area about 50 meters across on the Moon, so they got a topological map of the lunar south pole that is too rough to land a human there, but still provides an excellent guide to the local scenery.

Topographic elevation map of the Moon’s south pole regionThe simulated moonscape is in the picture above, and they created a topo map as well. Pretty cool! And useful, too: eventually, we may pack that peak with solar power panels, taking advantage of the eternal sunshine there to create energy for a lunar base… what I hope will eventually be a lunar colony.

Were taking the first steps here, the first real steps. Apollo showed us we could do it, and now our robotic proxies are mapping the way.

Take a look at that picture. We’re standing at the trailhead, looking own the path. It’s time to see where it leads.

Image credits: ESA/SMART-1/Space-X (Space Exploration Institute)

CATEGORIZED UNDER: Cool stuff, Pretty pictures, Science, Space

Comments (53)

  1. Todd W.

    Phil, did you notice the man laying down facing the camera in that simulated moonscape? His right foot is at the bottom of the picture, in shadow. The right half of his face is visible near the top of the nearer peak. Clearly a sign that a giant is chillin’ at the southern lunar pole.

  2. Ryan

    That is pretty cool. Although I’ve never been a fan of the idea of a lunar base (as opposed to an actual space station or a Mars base/colony) it would still be amazing compared to what we are doing now.

  3. Jeff

    Strikes me as a good place for any solar panels that a long-term mission would require.

  4. tacitus

    Eternal Sunshine of the Airless Kind?

  5. tacitus

    Of course the other attraction of Shackleton Crater is the region of eternal darkness beneath the rim. A perfect place for supercooled telescopes and instruments of all kinds.

  6. tacitus, that’s pretty good. I tried for something like that as a title but came up empty.

  7. tacitus

    Thanks! I aim to please (occasionally). You are welcome to steal it, though yours is pretty good too.


    Dr. Phil Plait:

    The simulated moonscape is in the picture above, and they created a topo map as well. Pretty cool! And useful, too: eventually, we may pack that peak with solar power panels, taking advantage of the eternal sunshine there to create energy for a lunar base… what I hope will eventually be a lunar colony.

    Would not the use of Stirling engines be a more efficient use of solar energy on the Moon?

    According to Wikipedia, a Stirling engine, placed at the focus of a parabolic mirror, can convert solar energy to electricity better than non-concentrated photovoltaic (solar) cells, and comparable to concentrated photovoltaic cells. On August 11, 2005, Southern California Edison announced an agreement to purchase solar powered Stirling engines from Stirling Energy Systems over a twenty year period and in quantity (20,000 units) sufficient to generate 500 megawatts of electricity. These systems, on a 4,500 acre (19 km²) solar farm, will use mirrors to direct and concentrate sunlight onto the engines which will in turn drive generators.

  9. kuhnigget

    Ever since I read Arthur C. Clarke’s “A Fall of Moondust” way, way back, I’ve been more interested in going to the moon than Mars. While Barsoom might have more potential in the very long run, the moon is just so damn close!

  10. Steve Martin

    I assume that the 0 elevation is what, sea level. So how was that determined?

    Great Map

  11. Huron

    Looks like rough terrain to establish a base, but no doubt that it could be done.

  12. IVAN3MAN

    Lunar Land of the Midnight Sun?

  13. IVAN3MAN

    Or how about: The Midnight Sun Mountains of the Moon?

  14. Pozsi

    Eternally sunny? Wouldn’t a lunar eclipse, spoil that?

  15. IVAN3MAN

    I better make that: The Midnight Sun Mountain of the Moon, before some bloody pedant points out that there is just the one mountain peak!

  16. John Phillips, FCD

    IVAN3MAN, it should be The Midnight Sun Mountain of the Moon as there is only one. I didn’t want you being dissapointed after going to all the trouble of your last post :)

    Now I just need someone to pop up and say that there is actually more than one there :)

  17. There is actually more than one there!

    (I actually have no clue as to what I’m talking about, but I feel this overwhelming urge to play out my part of this Intertubes phenomenon.)

  18. John Phillips, FCD

    I knew it, I should have just kept schtum :)

  19. Lem

    Off topic, but this recent gaffe by the Chinese may make life difficult for debunkers of faking the lunar landing. (follow “website” link on my name for the news article). Apparently Xinhua posted an article containing detailed conversation between astronauts during a flight that had not yet even launched – making it sound like someone leaked a script.

  20. mk

    OK… I’ll try this one more time. What would a Lunar Colony do, precisely?

  21. Brian T.

    @ mk,

    The Moon has abundant amounts of Helium 3, which can be mined for rocket fuel. And since lunar gravity is 1/6 the strength of Earth’s gravity, that means there’s a much a lower escape velocity needed to launch things off the Moon.

    In short, the Moon would be an ideal fueling station AND launch pad for any future space exploration. How cool is that? Check out the article linked below.


  22. Todd W.


    A Lunar Colony would colonize loons, of course.

  23. kuhnigget


    On the moon, see, we station our fleet of UFO interceptors, and, see, all the women have purple hair and, um, gosh, we could do all kinds of neat sciency stuff.

    On the other hand, wasn’t the first real income producing product out of North America beaver pelts? Surely we can do better than that on the moon. All them lunar turtles roaming about…


  24. tacitus

    Astronomers would kill for a lunar base from which they could deploy any number of telescopes in the eternal shadow of Shackleton Crater. The instruments would have a round-the-clock view of almost half the sky without any atmospheric distortions or risk of being blinded by the sun, and they could operate at near absolute zero giving them exquisite thermal control.

    Getting the equipment to the moon would be expensive, of course, but pales in comparison to the costs of delivering, operating and maintaining a single scope in orbit like Hubble. And if something goes wrong or an upgrade is needed, you simply have to walk outside to fix or retrieve the instrument.

    There is also the possibility of using liquid mirror technology on the Moon, which would allow for huge mirrors at the fraction of the cost of the traditional type–something which cannot be done from orbit.

  25. mk

    @ Brian T…
    Sorry, but I was laughing so hard at that article it took a couple passes to actually finish it. I could be wrong, (happens all the time with me. I’m not a scientist, cosmologist, astronomer… nor have I ever played one on TV!) but reading that all I could think of was the cost of flying people to the moon to build a colony to ultimately construct a mining operation to fly back Helium3 so we can ultimately start using a very theoretical “futuristic power plant” here on earth, I mean it seems so laughable. With all due respect. Is there a cost/benefit analysis for all that, by the way? And I thought getting oil out of the ground–here on Earth!– was costly! Heh.

    @ Todd W….
    Laughing for a different reason! Thanks.

    @ kuhnigget…
    Love your moniker! And just so… I fart in your general direction! ;^}

  26. mk

    @ Tacitus…
    Do you really mean to say that maintaining a lunar colony, shuttling people back and forth from Earth to Moon, running numerous telescopes there and all that this entails actually “pales in comparison” to the operation and maintenance of things like the Hubble telescope? Pales in comparison?

  27. tacitus

    Well, I was assuming that astronomy is not the only purpose of having an operational lunar base. I would have to agree that if maintaining the telescopes was the only reason why we were there, it would be more expensive, by far.

    But if we are going to put a base on the Moon anyway (which will happen eventually) then the delta cost of shipping, installing and maintaining telescopes there (over and above the basic operational costs of the base) would definitely be much cheaper than putting more scopes in orbit. Even the simplest of tasks during a Hubble repair mission costs millions in planning, design, and rehearsal because you only have one chance to get it right. Maintaining a Moon based scope, while still expensive by Earth standards, would not have nearly as much overhead as Hubble. Sure, shipping parts would still cost plenty, but the delta cost of maintenance would be much lower when you can just step outside get to the equipment. .

  28. Todd W.


    Well, you could have a greenhouse in the base, which will help provide a sustainable food source, lowering that requirement for transportation and resupply. Water would be a bit tricky, but there might be some way to have that available… Leave people up there for extended periods at a time, reducing the frequency (and cost) of shuttling people back and forth… Have a machine shop in the colony so essential items could be manufactured there, rather than ferrying them from Earth. Some manner of recycling system to reclaim and reused metal and plastics waste. Biological waste could be composted for use in the greenhouse.

    The cost of transportation could be cut down below what Hubble costs, but I think total costs of operation (colony maintenance, salaries, etc.) would be rather hefty.

  29. mk

    @ Todd and tacitus…

    Well, for me it is all coming down to whether or not it is worth it. I mean everything I’m hearing sounds like we are looking for a reason to build a colony on the moon. Like let’s build a colony so we can build and maintain telescopes… or let’s build these telescopes so we can create a colony. Seems sort of circular reasoning to me. I know the ultimate goal for most is to create a launching pad for Mars. Which just brings me back around to my original questions… what would we do there?

    Seriously, by the time men set foot on Mars isn’t more likely that we will have been able to send a probe there, have it pick up things and bring it back? Isn’t that more feasible in the near future? And shouldn’t we attempt that first? And if we do what then would be the purpose of sending humans up there?

  30. tacitus

    mk, if it all boils down to cost, then justifying any space mission beyond Earth’s orbit becomes difficult given the sheer expensive of such missions. There are some exceptions, like studying solar weather and Earth-crossing asteroids, for which the benefits for us back home are clear, but why bother sending probes to any planet, even the Moon, at the cost of hundreds of millions of dollars minimum, when the money could be used to improve the lives of people back home?

    After all, it doesn’t really matter in any practical way, whether there is microbial life on Mars. Such a discovery might have profound religious and philosophical implications but on a practical level, it affects our daily lives not at all.

    But it’s not just about the money. If we, as a species, are going to survive long term, then at some point we need to begin our outward migration. Out into the solar system first, but eventually (probably hundreds of years from now) out amongst the stars. Establishing outposts on the Moon and then Mars is but the first tiny step in that process. It doesn’t have to happen tomorrow, sure, but we can’t depend on robotic missions for ever. We will eventually need to go there ourselves if we’re going to continue to thrive as a species.

    As for the nearer term benefits, it’s worth remembering that a manned mission to Mars would probably have accomplished everything the multi-year operations of Opportunity and Spirit have done in about a week, and instead of taking a couple of weeks for the Polar Lander to confirm ice on Mars, it probably would have taken a manned mission about five minutes to do it. Robot missions are much cheaper, yes, but the amount of science they can accomplish is severely limited compare with what a manned mission could do. We will probably have several sample return missions before we get a manned mission to Mars, but once again, a manned mission could study hundreds of rock samples in the time it takes a robotic mission to pick a couple of samples to return to Earth.

    And the Moon is an excellent testbed for a mission to Mars. Establishing a long term base there would allow all kinds of experiments, trials, and tests to be carried out without the additional risks and expense of going to Mars. Being a great place for astronomy is just another factor that would be factored into the justification for going there.

    Frankly, I don’t see us getting to Mars in my lifetime (i.e. about 40 years, I hope) unless the costs of launching into orbit are slashed by the development, say, of a space elevator. I fully recognize that manned missions are extremely expensive (and we haven’t even factored in the cost of the inevitable failures and tragedies) but there is a lot more involved than just the cost, which is why I believe we will be going back to the Moon at some point in the next 20 years or so.

  31. mk

    @ tacitus…

    I did not mean to suggest that my main concern was money. When I said I wondered if it was worth it, it was not money per se I was speaking of. I don’t think we should shut down NASA so we can spend all that money on more Earthly things. Far from it.

    You say:As for the nearer term benefits, it’s worth remembering that a manned mission to Mars would probably have accomplished everything the multi-year operations of Opportunity and Spirit have done in about a week, and instead of taking a couple of weeks for the Polar Lander to confirm ice on Mars, it probably would have taken a manned mission about five minutes to do it.

    To which I would reply, “But Spirit and Opportunity have already done it!” So much for the speed thing. And besides… Has the deciding factor here really become speed of discovery? Learning Mars has ice in the span of an hour rather than a week, that’s what makes it worth it? Not for me.

    Survival of mankind. Well, I gotta be candid here and say if we go extinct, we go extinct. Whether we destroy all human life ourselves or we die out due to the Earth closing orbit with the Sun… Meh. The notion that mankind will somehow continue on indefinitely hopscotching planets and solar systems does nothing to sway me regarding lunar colonies and Mars missions. Far fetched to say the least.

    I say send a probe–send several probes!–have them pick up stuff, bring it back, study it. Do it again if necessary… and it can be done before we get back to the moon much less Mars. Why wouldn’t you want to do that? I suspect you would. But launching this insanely costly Moon-Mars program will likely make all that impossible. It would seriously delay any real discoveries.

    It probably could be done. (Moon-Mars) But should it? If it can be done with probes more cheaply… and yes, swifter! well then let’s do it!

    Anyway, thanks for the back and forth. I doubt either of us has changed the others mind, but I like to hear where Moon-Mars folks are coming from.

    Cheers. (oh and if you have something to add, I will be checking back for a while.)

  32. Todd W.


    Another reason for pursuing off-Earth colonies is expansion. At some point, barring any major catastrophes or some other phenomena to curtail population growth, the human population is going to be too big for the planet to sustain. So, before we reach that point, we better have someplace for people to go.

    Kinda like metro areas continually grow, eventually attaining populations beyond what they can sustain, so too for the planet. At least, I can envision that happening.

  33. kuhnigget

    Why the moon? Why North America?

    Seriously, while economics had a lot to do with colonizing the “new world,” it wasn’t the only reason behind it. Protecting empires, fleeing tyrannical regimes, setting up your own tyrannical regime, the thrill of it all…there were lots of reasons for going. Same will apply to space colonies, be they on the moon, mars, or…sighhh…L5 (…in ’95!).

    Personally, one reason I think western nations (and I include Japan in that group) should be going to the moon has to do with political and global security. I don’t really want the Chinese or Russian thugocracies getting there first!

  34. tacitus

    Again, cost benefit analysis alone will continue to favor robotic missions for the foreseeable future, I don’t dispute that. But the fact that a manned mission could accomplish much more than a single robotic mission closes the gap a fair amount. After all, just about everything achieved in the 35 years worth of unmanned missions to Mars could easily be done many times over in one manned mission today. Yes, we have the data in hand and waiting 35 years until we can go there ourselves wouldn’t make much sense, but once you add up the total cost of the Mars program over 35 years, the price of a single manned mission to Mars doesn’t look so bad when you consider the advantages of having scientists actually there collecting and analyzing data.

    It will take another 30 years of robotic missions to come close to collecting equivalent samples that could be collected in one manned mission, and they don’t exactly come cheap either.

    Again, not arguing that manned missions would be as cost effective today, but the gap is not as wide as most people think when the overall scientific return on investment is factored in.

    Then there are plenty of other reasons for going:

    1) Inspiring the next generation of scientists and engineers
    2) Long term survival of the human race (forgive me if I believe this to be important!)
    3) Technology spin offs from a manned Mars program
    4) Benefits to astronomy, as discussed before, in discovering exoplanets and studying dark matter, dark energy, etc.
    5) Discovery and exploitation of resources being exhausted here on Earth (it’s going to run out eventually no matter what we do)
    6) The sheer entertainment value of it all (not to be underestimated).
    7) Natural curiosity.
    8) National pride (just wait until Russia or China announces their manned mission to the Moon or Mars) and our competitive spirit. Someone will want to be first.

    None of these is a good enough reason in itself, but they have a cumulative effect and at some point in the future (could be a long time though) the costs will come down and one or more of these other factors will push the balance of the equation over to the other side and we will go.

    In the long term we definitely *should* go, but I think you will have noticed by now that I am not being dogmatic about wanting to go sooner rather than later. Selfishly, I would love to see a manned mission to the Moon beginning right away — it would be fascinating to watch and follow along from home. But given how difficult and expensive it would be, I am under no illusions that it will likely be many years before we can justify the risks and costs.

  35. tacitus

    Oh, and I forgot to add:

    9) Understanding the history and current conditions of the Moon, Mars and other planets helps to understand the history and current conditions of our own planet and what might happen in the future.

  36. IVAN3MAN

    @ Todd W.

    If we’re going to have colonies on other worlds, then let’s make sure, by means of a strict selection process, that none of the colonizers are religious fruitcakes, otherwise we’re going to have the same problem of having to deal with bloody fundamentalists as we do here on Earth.

  37. mk

    Yeah, well let Russia and China waste all that money, all that time and all those resources hoping to get to the moon. They may get there and then what will theydo? Nothing.

    Meantime, we’ll be studying soil and rocks and–who knows?–microbes! we brought back from Mars with a probe or two.

  38. mk

    We’ll also be discovering what’s what with potential life bearing places like Europa! So much to discover so little time!

  39. kuhnigget

    @ mk

    Look up “Seward’s Folly.”

    Hu-men can always find something to do!

  40. mk

    Seward’s Folly? Familiar with it, thanks.

  41. tacitus

    Well, I guess for what is probably my last comment on the subject I should just point out one thing is certain–whether it is sooner or later, I have no doubt that we will be going to back to the Moon and on to Mars eventually.

  42. well, this is hardly a scientific motive for sending humans, and more a human reason:

    because we’re curious, and because we can (well, in the future anyway). most the things people have done, discovered or invented was originally motivated by someone’s naked curiosity. and I think that curiosity is going to win out even if we didn’t have good reasons to go. It’s like going on vacation: much cheaper to just look at photos and read about places, but generally we want to BE there, and touch/experience stuff for ourselves.

  43. Slowly but Surly

    A lunar base I can see, but a lunar colony? Perhaps the BA could explain, because when I see ‘colony’ I think moving there with the wife & family… Sorry, I just don’t see it this century. It would make a vacation in a maximum security prison look like fun.

  44. Todd W.


    “The meek shall inherit the Earth” comes to mind. Let those who don’t have the courage to face reality as it is without some sort of deity have the Earth, while the rest of us go out into the great partially known.


    There’s no reason to completely suspend probes and robotic missions in order to pursue manned missions and settling of other worlds. What is your opinion of the early European explorers that ventured outside their known lands? If they had possessed probes and robotic technology, should they have stuck to those and never ventured across the ocean or overland into Asia? Human exploration and settling outside of Earth is very similar, and the same motives that drove early European explorers and settlers (and those of every region inhabited by humans) are the same motives that will likely drive manned space endeavors.

  45. Radwaste

    Sorry, Phil, I wrecked the link. I try again.

    Gee, there’s always somebody arguing to stay at home. Here are a few things we wouldn’t know if we hadn’t gone.

    And arguments about going make me think of that confrontation Phil posted earlier over the LHC.
    You build things and do things to see what you can do.

    Yes, there are undeveloped and unused regions of the Earth. Those will be explored by other people. We don’t stop everything else to do this. We don’t even come close.

    And about risk: I saw someone post the other day that “going to Mars is too risky”. The poster, like so many other people, has a vested interest in the idea, being a taxpayer, but no background whatsoever to make the call w/r/t risk. If a pilot volunteers for a one way mission to Mars, it’s still his or her business first. Being that pilot could give a life meaning. Maybe that’s why others would try to prevent such a thing.

    Manned missions rock for the simple fact that someone of exceptional skill braved the risk and won. If you can shake Neil Armstrong’s hand and not be awed at what he has done, I suggest there’s something wrong with you. There are many more like him, who will make the most of an opportunity to forge ahead and make us proud.

    Who can you point to as a hero? Someone who plays with a ball? Someone who programs computers?

    Americans will spend a ton of money this year watching people play with a ball. How much, do you think, that is, relative to Apollo, and how much does playing with a ball advance society?

  46. Slowly but Surly

    @Radwaste says “Manned missions rock for the simple fact that someone of exceptional skill braved the risk and won. ”

    True, but that’s not science. Don’t get me wrong… I really love the space program, but I think the space station could have funded a lot of really cool space probes & telescopes.

    Are there advantages to humans in space? While its true that were are much better at responding to unexpected events than robots, I strongly suspect that the cost in food, water, air, heating/cooling, radiation protection& so are far out way this advantage. If we crash a probe on Mars, we can cheaply correct the problem and send two more.

    If I’m wrong, and there is a scientific advantage to humans in space, I’d really like to hear it!

  47. kuhnigget

    @ surly

    True about the ISS, but then the ISS isn’t exactly a program based on science, but rather geo-politics. The fact we are learning tons about how to do real work in space is an unexpected (Oh, I know, I know!) and ancillary benefit.

    Besides, at my lunar colony, there won’t be any “wife and kids.” 😉

  48. kitty

    Shackleton crater? Now there is someone that deserves a crater named for them! I’m taking it the crater was named after Sir Ernest?

  49. Gary Ansorge

    All of these reasons for returning to the moon have ignored the most COST effective reason. To use lunar resources (O2,Aluminum,Silicon, etc) to build solar power satellites to beam/sell power to an energy starved earth. 90% of all space construction could be met from lunar resources. It’s just HEAVY construction, folks, brick, aluminum and silicon. Only really high tech gizmos need be supplied from earth.

    GAry 7

  50. kuhnigget

    I grew up inspired by the dreams (that’s the good kind) of Peter Glaser, Gerard K. O’Neill and others. Time was, “L5 in ’95” wasn’t just a fantasy…or so it seemed to a pie-eyed boy from Podunk. I confess I’ve been out of touch with the solar sat research for a while (15 years or so). How have things progressed? Sorry to wander OT.

  51. Gary Ansorge


    Means of using the mag rail to accelerate payloads beyond escape earths velocity have been solved. It was just a matter of using single loop, very high current mag. coils in the later stages of the acceleration cycle.
    Check out the yahoo special interest group for SSI(space Studies Institute).


    Gary 7


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