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It’s almost entirely craters, while the side we see is dominated by huge lava filled basins called maria (Latin for "seas"). Why is that? Well, it’s known that the crust on the near side is thinner, so it’s easier for big impacts to have punched holes in the crust and allowed magma to bubble up (this was billions of years ago when the inner Moon was still molten). But why does one side have a thick crust and the other thin? No one knows. Interestingly, it’s probably tides from the Earth that forced the Moon to have this asymmetry line up with us. The Moon causes tides in the Earth, but the Earth does the same for the Moon, and the tides we create on it are much more powerful, since the Earth is far more massive than the Moon. Tides like to stretch things, and they also like to have any imbalance settle along the Earth-Moon line. /[UPDATE: Some folks were questioning my next claim, that the far side of the Moon is heavier (technically, has more mass) than the near side. The thing is, I think they're correct! The crust is thicker on the far side, but it's made of less dense material than the stuff below it. That means the half of the Moon farthest from the Earth is slightly less massive than the half facing the Earth! Or, in other words, the center of mass of the Moon is a bit closer to the Earth than the physical center of the moon (see here , and scroll down to the bit about the Moon's crust). In other other words, I was wrong. Thanks to everyone who pointed this out to me. Ironically, just tonight I was helping my daughter with her science homework. The topic? Buoyancy and density! That helped me understand my mistake here. Anyway, I've struck it through; I'll keep it up so people see the mistake I made. What I said about common sense is still right, though, and is doubly true here for me!]/ You might think the heavier side would settle toward the Earth, since that’s "down", but in fact tides don’t care if the heavier side is pointed directly toward the Earth or directly away, as long as it’s on the Earth-Moon line. In our case, the heavier side of the Moon points away from us. Weird. But while the Universe has to follow the laws of physics, it doesn’t always have to follow our common sense. You can explore the Moon yourself; the folks at LRO also released this very cool picture of the Moon as seen from all sides, in 60° increments. Scanning over this is fascinating. I’m used to looking at close-ups, so seeing the overall picture is very, very cool. And useful. Maps like these will be used to gauge where to send more probes, and, eventually, people. I can’t help but wonder: in a few decades, will school children have to memorize the locations of Mare Orientale, Copernicus, and Rupes Recta… before taking a field trip there? /Image credit: NASA/GSFC/Arizona State University/ ------------------------------------------------------------------------ / / /Related posts:/ /- The extraordinary face of the Moon - Lunar rock and roll - Gettin’ high on the Moon - There’s a hole in the Moon! / March 12th, 2011 7:00 AM Tags: far side , Lunar Reconnaissance Orbiter , Moon by Phil Plait in Astronomy , Pretty pictures | 82 comments | RSS feed | Trackback > 82 Responses to “The extraordinary back of the Moon” 1. 1. frag971 Says: March 12th, 2011 at 7:05 am <#comment-367297> Dat ass. … Sorry couldn’t resist. Great stuff! 2. 2. IronSky Says: March 12th, 2011 at 7:38 am <#comment-367311> Where are the Nazis!? 3. 3. Just Wondering Says: March 12th, 2011 at 7:40 am <#comment-367312> The closer side is thinner? Could centrifugal forces (often said to be fake, but a different way of representing the forces in action) have something to do with this? The moon was swinging around Earth fast enough to move molten rock to the outside? It got piled up on the outside because there was no rotation of the moon to spread the crust around. Granted, this would probably only work if the moon became tidally locked while it was still very malleable….. I could be missing something and end up horribly wrong, but… make sense to me…. 4. 4. fatherdaddy Says: March 12th, 2011 at 8:06 am <#comment-367318> I volunteer to chaperon the kids on that field trip. 5. 5. Bill-O Says: March 12th, 2011 at 8:14 am <#comment-367320> But how’d the moon get there? How’d it get there? Can you explain that to me? How’d it get there? C’mon. C’mon. You pinheads. 6. 6. Non-Believer Says: March 12th, 2011 at 8:23 am <#comment-367324> Its so different. I like our side better. Just a personal aesthetic preference. Not for any valid reason. I guess my common sense is off. I would have guessed the thicker side was the outside, kind of like the kid on the end of “crack the whip” getting all the energy and flying off. But I am not remembering my Newtonian high school science and cannot remember the name of the law or its rules. Anyway, clearly if that was the answer, smarter people than me would have figured that out, so I’m wrong. 7. 7. Oli Says: March 12th, 2011 at 8:25 am <#comment-367325> Why are there so many craters at the Moon’s poles? 8. 8. jearley Says: March 12th, 2011 at 8:28 am <#comment-367326> Great! Now, how about a shot of the Moon from over the poles? I’ve never seen any large scale photos from that perspective, and it would be cool. 9. 9. mln84 Says: March 12th, 2011 at 8:33 am <#comment-367329> BA> “In our case, the heavier side of the Moon points away from us.” Can someone expand on this? (BA, maybe a new post…) I thought the moon was nearly spherical. If so, and the crust was thinner on our side (as you said) wouldn’t that mean the core is off-center toward us? And if that is the case, isn’t the core more dense and therefore the heavier side is toward us? Is my problem in the “nearly” spherical bit or is there something else I’m missing? Thanks. 10. 10. DrBB Says: March 12th, 2011 at 8:45 am <#comment-367331> Wait, is that the Supermoon??? Or just the regular one? Okay, sorry to carry my grumpiness over from a different thread. Utterly cool picture and thanks for posting it. One of those things where you’re pretty sure it’s just gonna look pretty much like the other side, no reason for it to be totally different you’d think, and then Wow, wait a sec…. the Far Side really is pretty strange! I’d like to echo @4 Oli’s query–I seem to recall hearing an explanation but can’t remember what it was. I wouldn’t mind hearing what the explanation is for the difference in the crust and “heaviness” of the two sides, too–something to do with being tidally locked and experiencing centrifugal effects…? 11. 11. Andrew W Says: March 12th, 2011 at 8:54 am <#comment-367332> 4. Oli The polar craters appear more prominent because the sun is at a low angle, so there are longer shadows, the photos selected for the mosaic all appear to have been taken at the local noon. 12. 12. Chris Merchant Says: March 12th, 2011 at 9:44 am <#comment-367345> Business in the front, party in the back. The man in the moon has a lunar mullet! 13. 13. Bob Studer Says: March 12th, 2011 at 9:59 am <#comment-367349> “I can’t help but wonder: in a few decades, will school children have to memorize the locations of Mare Orientale, Copernicus, and Rupes Recta… before taking a field trip there?” No, because by then, the way things are going, the current “lies” will probably have been replaced by Biblical Truth. Sheesh. 8-/ 14. 14. hhEb09'1 Says: March 12th, 2011 at 10:05 am <#comment-367354> @mln84 You’re right, more or less. It is not just the crust involved in the mass profile of the moon, but it’s been generally said that the heavy parts (mascons) of the moon are concentrated on the near side. And, it’s not along a line directly towards the earth. I’m not sure what the BA means. Perhaps he can explain, or give us a reference. 15. 15. Gjeff Says: March 12th, 2011 at 10:26 am <#comment-367368> Dean Martin sang “When the moon hits your eye like a big pizza pie. That’s amore.”. That might explain the thin crust and thick crust options on either side. The toppings on the moon look interesting but are not that tasty. Perhaps what looks like craters are actually pepperoni slices. 16. 16. Robert S-R Says: March 12th, 2011 at 10:33 am <#comment-367370> A cross section of the Moon along the Earth-Moon line would help me picture the crust as well, but I have a fair idea of what it might look like. I bet the lop-sidedness of the Moon is the result of the nature of the Moon’s formation (Mars-sized planet smashed into Earth, chunks coalesced and stayed in orbit). The fact that the “heavy” side is away from us doesn’t surprise me, since it sounds just like the force that causes high tides on both sides of the Earth even when the Sun and Moon are pulling the same way. (Am I close? I’ll be honest, I don’t understand the tide thing at all, but the two concepts sound similar.) 17. 17. John Paradox Says: March 12th, 2011 at 10:45 am <#comment-367371> So the photo is being mooned by the Moon? J/P=? 18. 18. Thameron Says: March 12th, 2011 at 10:46 am <#comment-367372> Here’s a question I’ve never seen the answer to. How long after the Moon’s formation did it become tidally locked? When was the last time a creature on Earth could look up and see that back side? 19. 19. Rodrigo Says: March 12th, 2011 at 10:53 am <#comment-367373> Man, great stuff, but can I ask for a 3D full moon animation? Please? :D 20. 20. Don Q Says: March 12th, 2011 at 11:17 am <#comment-367378> 3D pictures of the moon? This would be as simple as a series of pictures with something less than 60 degrees separation like the ones posted here. I cant quite get the cross-eyed 3D thing to work with 60 degrees. 21. 21. sudeep Says: March 12th, 2011 at 11:24 am <#comment-367381> i have never seen this picture 22. 22. Gary Says: March 12th, 2011 at 11:39 am <#comment-367385> Moon has a front side, moon has a backside. You can’t explain that! :) 23. 23. Minda Says: March 12th, 2011 at 11:40 am <#comment-367387> looks like moon covers earth from meteorites pretty well, the other side of moon really got hard hit over time. just a thought… 24. 24. Carson Myers Says: March 12th, 2011 at 11:40 am <#comment-367388> I’d like to see this projected onto a flat map 25. 25. Elwood Herring Says: March 12th, 2011 at 11:42 am <#comment-367390> @Thameron: I’m not sure but I’ll hazard a guess that the Moon became tidally locked well before eyes evolved in any animal; ergo us humans are the first ever to see the far side. 26. 26. Martha Says: March 12th, 2011 at 11:51 am <#comment-367395> Hey the moon is round. Who are you to say it can even have a “back?” You scientists just think you know everything. : ) 27. 27. colluvial Says: March 12th, 2011 at 12:13 pm <#comment-367400> I thought the reason there were more craters on the far side of the moon was because it’s less protected by the Earth. 28. 28. Liath Says: March 12th, 2011 at 12:40 pm <#comment-367403> Gjeff says “When the moon hits your eye like a big pizza pie, that’s amore.” I really wish you hadn’t said that. That blasted song will be floating around my brain for the rest of the day. It’s almost as bad as “Suddenly Seymore.” 29. 29. liath Says: March 12th, 2011 at 12:45 pm <#comment-367407> #23 Minda I think the earth got hit with as many meteors as the moon. We just eroded the craters and the moon never learned the trick of keeping an atmosphere. 30. 30. DrBB Says: March 12th, 2011 at 1:24 pm <#comment-367423> @26 Martha: sounds like you’re another refugee from the Supermoon thread. ;-) I’d like to endorse Gjeff’s opinion re pepperoni, but where are the anchovies? None, I hope. I hate anchovies. I do seem to recall that the thick/thin crust thing explains why the sides look so different: that the thinner crust could be penetrated by meteor strikes and magma (whatever the correct term is) flowed out to create the mares, evidence that the moon once had a molten core though it doesn’t any more. Correct? [oops, I see Phil addressed that--I should read the words as well as look at the pretty picture] Glad to have the answer/speculation about when it became tidally locked–I was wondering about that as well. 31. 31. Steve Says: March 12th, 2011 at 1:36 pm <#comment-367430> “I can’t help but wonder: in a few decades, will school children have to memorize the locations of Mare Orientale, Copernicus, and Rupes Recta… before taking a field trip there?” Unless the powers that be get their collective fingers out, I doubt whether school kids in the future will even know we went to the moon at all! 32. 32. Ciro Says: March 12th, 2011 at 1:40 pm <#comment-367433> http://www.designspongeonline.com/2011/03/moon-diamond.html 33. 33. Dark side of the Moon | My Thoughts Says: March 12th, 2011 at 1:45 pm <#comment-367434> [...] Dark side of the Moon Posted on March 12, 2011 by Steve| Leave a comment via blogs.discovermagazine.com [...] 34. 34. Thameron Says: March 12th, 2011 at 1:52 pm <#comment-367437> @ 25. Elwood Herring I would imagine so since the history of life on Earth was dominated by one celled organisms for about 3 billion years or so and we multi-celled critters didn’t come on the scene until about 0.75 billion years ago or so. Feel free to jump in with the exact figures if you have them. It’s just that there seem to be certain points that them thar pointy headed scientists never give a figure for. The Earth is 4.5 Billion years old. We get that particular figure a lot, so when on that scale did the collision with the mars sized body take place? Before it started? After? If so how long after? How close to the Earth was the Moon when it coalesced? And of course when did it become tidally locked? I have not seen those figures/dates in my admittedly cursory travels. All I want is the timeline. Is that too much to ask? 35. 35. Bob H Says: March 12th, 2011 at 1:56 pm <#comment-367441> Actually, as mln84 pointed out, the core is heavier than the crust (that’s why the crust is on top) so the light side is the back side. Assuming the moon formed near the Roche limit and migrated to its current position then the backside would be more exposed to outlying moonlets and external asteroids than the front. 36. 36. Old Rockin' Dave Says: March 12th, 2011 at 2:05 pm <#comment-367446> Not quite on topic, but Liath, I often get songs stuck in my head, and what never fails to dislodge them is to listen to “I Fought the Law” by the Bobby Fuller Four. Sometimes I have to listen to it twice, but it always works. 37. 37. DrBB Says: March 12th, 2011 at 2:49 pm <#comment-367463> @36: Now that’s a great tip. I think William Gibson was the one who said the only way to get a bad media virus out of your head is to go focus on a worse one. I believe the recommended treatment involved the film “Surf Nazis Must Die,” so the aural equivalent might be, I dunno, ABBA or something. But “I Fought the Law”–now there’s an antidote I can get behind. And even if it doesn’t work, at least you’ve been listening to a mad wonderful kickass piece of rock history. Clash version’s not bad either. 38. 38. DrBB Says: March 12th, 2011 at 2:56 pm <#comment-367465> Here’s a relevant query though: every time I glance at the lower-res version here I get this really strong impression of a vertical line down the middle. There does seem to be a series of craters extending up from the south pole toward the center that are in a strongly linear arrangement, then some smaller ones going north that reinforce the impression. What’s up with that? A comet broken up like Shumaker-Levy and striking in rapid series? Or just my brain seeing order where there’s only chaos? ..adding, there are a couple other linear patterns, such as the one from about 11 o’clock at the upper left stretching down toward center at an angle pointed at about the 2-3 o’clock position. Wonder if any of this is “real” or just random? 39. 39. Nk_knight Says: March 12th, 2011 at 3:06 pm <#comment-367467> Definitely thought that there was suppose to be glass tubes that aliens lived on the dark side of the moon, right? 40. 40. JeffB Says: March 12th, 2011 at 3:11 pm <#comment-367469> @DrBB There are some distinct linear artifacts from the mosaic assembly that lie along that central vertical line. These are especially noticeable at the poles. Otherwise, there are so many craters on the backside that almost anywhere you draw a line, there will be craters along it! 41. 41. Chris R Says: March 12th, 2011 at 3:20 pm <#comment-367471> @38 DrBB: I’m guessing that’s mostly your brain tricking you into seeing those lines. It doesn’t help that the two halves are stitched together pretty blatantly (no fault of the LRO guys, just the way it worked out). You’re probably subconsciously following that line through the center. The other line you mention is very likely just coincidence. Not to diminish the “comet breaking up” hypothesis, as that’s far more interesting. 42. 42. Anchor Says: March 12th, 2011 at 3:21 pm <#comment-367472> “Ask, and ye shall receive.” Okay, folks at LRO. North and South Polar-centered views would be nice too. OT: Hey, Phil, have you seen the Kepler Orrery yet? 43. 43. Chief Says: March 12th, 2011 at 3:43 pm <#comment-367479> I’ve always liked the explanation by Author James P. Hogan in his Giant’s series of novels on the crust differences in depth. 44. 44. ChrisP Says: March 12th, 2011 at 4:00 pm <#comment-367483> @34 Tameron: Now you’ve gone and got me all curious. I wonder if I can do an approximation once I get the spare time… (My intended method for finding the time until the moon would be tidally locked would be to use the Earth-moon gravitational Roche limit as an approximation for the radius at which the moon coalesced, and use some combination of conservation of angular momentum and tidal torques to do the estimation. However, I can’t quite figure out how to piece together the appropriate equations) Closer to on topic: very nice picture, definitely my personal favorite of the two ‘faces.’ Much less chaotic at first glance, at least as far as contrasts go. 45. 45. DrBB Says: March 12th, 2011 at 4:52 pm <#comment-367502> @40. JeffB Yup, right, the image stitching is much more obvious in the high res–that’s what was doing it. No less exciting and fascinating an image for the lack of strange linearities. Though ancient alien ruins or a UFO base or two would definitely improve it. 46. 46. DrBB Says: March 12th, 2011 at 4:55 pm <#comment-367504> @43: I’ve always liked the explanation by Author James P. Hogan in his Giant’s series of novels on the crust differences in depth. Okay, Chief, we’re waiting. Do you wanna share that story with the rest of the class? 47. 47. Kaleberg Says: March 12th, 2011 at 5:15 pm <#comment-367511> The first 3D picture of the moon was taken in 1858. They took advantage of libration to make a stereogram. Of course, any newer ones would be way cooler. 48. 48. owlbear1 Says: March 12th, 2011 at 6:46 pm <#comment-367539> Are there any clearer shots of the poles? Cuz thats where we want to be looking. :) 49. 49. Scott Says: March 12th, 2011 at 7:16 pm <#comment-367549> Why don’t I see The Watcher’s moonbase?! :O :) Selene’s exposed backside on your blog… sir, where is the NSFW? 50. 50. Don Q Says: March 12th, 2011 at 7:55 pm <#comment-367583> I think the apparent ‘line’ of extra craters down the middle of the pictures might also be the result of the lighting on the different halves. The shadows on the left half of the ‘photo’ are on the left side of the craters, on the right half, they are on the right side of the crater. Down the middle, there are a lot of split craters with shadows on both sides. “Shadows on both sides… How do you explain that!” Also, even though the component photos of the composite are taken at comparable moon local times, when the segments are ‘wrapped’ to make the whole picture ’round’ again, the shadows along the edges of the composite are cosine-scaled the same as the craters. Average shadow in the result decreases to zero along the edge of the photo and is max toward the center. 51. 51. Keir Says: March 12th, 2011 at 8:41 pm <#comment-367589> I thought the far side of the Moon is more pockmarked because the near side lava plains (maria) are way older, and sort of “fossils.” Thus, if Moon wasn’t in sync with the Earth, it would look more like Mercury, but because it has been in sync with the Earth for billions of years, the side we see hasn’t had so many impacts as the far side, which is unprotected by our close gravitational relationship. The possible near-side lunar impactors have been scooped up by the Earth, and not have hit the side we see, but instead hit the Earth. 52. 52. DLC Says: March 12th, 2011 at 9:22 pm <#comment-367594> Phil, I love the pics. I wish I shared your optimism, but I fear that Gene Cernan will be the last man to have stood on the lunar surface. 53. 53. Messier Tidy Upper Says: March 12th, 2011 at 9:46 pm <#comment-367596> @^ DLC : So you reckon the Chinese will only be sending women taikonauts there then? ;-) Being serious now, I also share that fear. Certainly as far the US goes. A return to the Moon (by humans not just spaceprobes) always seems to be suggested for twenty years in the future – and has been for about the last forty years or so since we left it in the early 1970′s. Same thing as sadly applies to cheap & prevalent use of nuclear fusion and a human landing on Mars. :-( 54. 54. Messier Tidy Upper Says: March 12th, 2011 at 9:46 pm <#comment-367597> Great image. Thanks. :-) /But why does one side have a thick crust and the other thin? No one knows./ Could the Earth’s gravity have pulled the lunar core slightly towards the Earth-facing side thus creating the imbalance of maria (luna “seas”) & other volcanic activity on that hemisphere and letting the farside crustr get thicker and cooler and more inert? Think I might’ve heard / read that explanation for that disparity once. EDIT : Just seen that (#9.) mln84 seems to be saying something similiar too. I recall discussing the topic of the lunar farside & its differences a few (?) weeks ago here too. Of course, there’s always the alternative “pizza” theory that one half crust is pan-fried and thus thin whilst the other is thick or cheesy crust – all covered in green cheese, natch! ;-) 55. 55. Messier Tidy Upper Says: March 12th, 2011 at 10:15 pm <#comment-367602> /I recall discussing the topic of the lunar farside & its differences a few (?) weeks ago here too./ See : http://blogs.discovermagazine.com/badastronomy/2011/02/22/the-extraordinary-face-of-the-moon/#comment-360777 Or scroll down to comments #78 & 79 that on the first nearside image post on this which is linked in the opening post here. See : http://en.wikipedia.org/wiki/Far_side_of_the_Moon#Differences For what Wikipedia in its vast collective wisdom says about it too. :-) @13. Bob Studer : / No, because by then, the way things are going, the current “lies” will probably have been replaced by Biblical Truth. Sheesh. 8-/ / I’m more optimistic on that. From my admittedly more distant vantage point it looks like Creationism is in decline and not likely to rise again. The US courts have beaten it back several times and they seem to have been so thoroughly discredited that I very much doubt they’ll suceed in forcing their nonsense on future generations – at leats not outside their very narrow and hopefully ever-shrinking circles. 56. 56. Messier Tidy Upper Says: March 12th, 2011 at 10:55 pm <#comment-367609> @ ^ “They” there being the Creationists / ID-iot mob not the Courts in case that was unclear! ;-) (Correction for bad grammar.) @47. Kaleberg : /The first 3D picture of the moon was taken in 1858./ Interesting – thanks. :-) But they wouldn’t have had the Lunar Farside on that! ;-) @30. DrBB : /I’d like to endorse Gjeff’s opinion re pepperoni, but where are the anchovies? None, I hope. I hate anchovies. / *WHAT!?!* See : http://www.youtube.com/watch?v=KNHaiSs7F5E I’m with Dr Zoidberg on this – <3 *love* <3 anchovies! Nothing tastier. :-) 57. 57. Gary Ansorge Says: March 12th, 2011 at 11:20 pm <#comment-367612> Hummm, lunar crust thicker on the far side. I guess this is what happens when two massive bodies revolve around a common center of gravity. The denser part gets thrown to the far side of the bodies. Since the moon doesn’t rotate and it cooled more rapidly than earth, the densest part is static, while any such mass distribution on earth would end up throughly mixed as our rotation drags against the lunar tides. Eh, sounds logical to me,,, Gary 7 58. 58. Il lato B della Luna | Siamo geek Says: March 13th, 2011 at 3:01 am <#comment-367640> [...] La faccia nascosta della Luna è stata fotografata per la prima volta nel 1959 dalla sonda sovietica Luna 3. (via Discover) [...] 59. 59. NCC-1701Z Says: March 13th, 2011 at 6:43 am <#comment-367678> Everyone keeps talking about the far side, but I’m yet to see any comics. 60. 60. Messier Tidy Upper Says: March 13th, 2011 at 6:55 am <#comment-367679> An interesting fact I stumbled across tonight that gives an idea of scale – and how lucky Earth is when you consider half the terrestrial (“rocky”) planets in our solar system – Mercury & Venus lack moons altogether : ***** “If we could transport Phobos and Diemos to our own Moon, they would fit comfortably inside the wide crater Copernicus with room enough for two moons of similar size.” - Stephen James O’Meara, page 102 /“The Demon Sprites of Mars”/ in /Sky & Telescope/ magazine, June 2001. ***** Copernicus (crater), of course, is on the other near side of our Moon – but that still gives an impressive indication of relative sizes of the three moons of the terrestrial planets – Luna, Phobos & Diemos. PS. Straying even further off-topic here, sorry, but does the BA or anyone else know if anyone has searched for Mercury trojans? I know they’ve searched for “Vulcanoid” asteroids inside Mercury’s orbit – but have they looked for trojans around that innermost moon-like world too? PPS. Want to confuse others? Print out this photo of lunar farside and one of Mercury and see how many people can pick them apart! ;-) 61. 61. Messier Tidy Upper Says: March 13th, 2011 at 7:25 am <#comment-367685> See : http://en.wikipedia.org/wiki/Copernicus_(lunar_crater) & http://en.wikipedia.org/wiki/Phobos_(moon) & http://en.wikipedia.org/wiki/Deimos_(moon) For comparison purposes and more on those objects noted above. :-) PS. Happy 230th anniversary Ouranos* serendipitiously discovered – as a suspected comet – March 13th 1781 by Wilhelm Herschel. :-) * That’s how I spell it, its the correct Greek spelling version & I’m sticking to it, durnnit! ;-) 62. 62. chris j. Says: March 13th, 2011 at 8:25 am <#comment-367694> wow, nearly 60 replies, and not one… “that’s no moon…” 63. 63. Jeff P. Says: March 13th, 2011 at 8:34 am <#comment-367695> Awesome picture. And it’s stunning that one side is so messed up (Maria) and one side is so clean. I’m curious, would nights be a little brighter if the back-side of the moon faced us all the time vs. the frotn? M thought is the lava fields, do a very poor job of reflecting light so maybe up to 20% of the light that could be reflected is sbsorbed or dulled. 64. 64. William Roeder Says: March 13th, 2011 at 8:35 am <#comment-367696> > But how’d the moon get there? How’d it get there? > Can you explain that to me? How’d it get there? C’mon. C’mon. DC or TLC show ‘what if there was no moon’ 10 million years after the earth formed a collision with a large body ejected the mass that became the moon. That’s why the earth is tilted, has a double core, and why the moon is mostly the same as the Earth’s crust (it has no core.) 65. 65. Messier Tidy Upper Says: March 13th, 2011 at 9:05 am <#comment-367699> @61. chris j. : /wow, nearly 60 replies, and not one… “that’s no moon…”/ Hmm .. just for you then, chris : That’s no moon .. That’s **our** Moon! ;-) Which faras I’ve heard, *does* have a core actually right? PS. Where’s Ivan3Man when you need him, eh? ;-) 66. 66. Messier Tidy Upper Says: March 13th, 2011 at 9:15 am <#comment-367700> @ 63. William Roeder : Just in case you don’t already know (& I strongly suspect you do) I think that was referring to this meme : http://blogs.discovermagazine.com/badastronomy/2011/02/11/you-cant-explain-bill-oreilly/ http://blogs.discovermagazine.com/badastronomy/2011/01/31/bill-oreilly-tidal-bore/ But ardent right-wing Fox fans, needn’t worry – the BA is quoted on the back cover (sort of) : http://blogs.discovermagazine.com/badastronomy/2010/05/13/glenn-beck-wait-a-sec-whos-the-idiot-again/ promoting one of Glenn Beck’s books! ;-) 67. 67. Messier Tidy Upper Says: March 13th, 2011 at 9:33 am <#comment-367707> PS. The above comment is speaking as an Australian who doesn’t get Fox (or any pay-TV) & who is neither left-wing nor right-wing but apolitical hating the idiocies of both sides. A pox /(& a-taking of the mickey)/ on both their houses! ;-) I haven’t seen enough of either Bill O’Reilly or Glenn Beck to say whether the BA is justified in his comments or being hyper-partisan against them. 68. 68. Ken B Says: March 13th, 2011 at 9:55 am <#comment-367709> Anchor (#42): “Ask, and ye shall receive.” Okay, folks at LRO. North and South Polar-centered views would be nice too. Or just wait for Google to bring “Google Moon” up to date, like “Google Earth”. Then you can get any view you want. :-) 69. 69. Marj H. Says: March 13th, 2011 at 11:08 am <#comment-367714> Maybe it’s like a lot of things in nature. The weaker, lea side is the protected side facing earth. The stronger side, that gets hit most by all the crap flying around out in space, faces out. 70. 70. Mike Says: March 13th, 2011 at 12:46 pm <#comment-367728> @entry 34: I believe the moon was about 14,000 miles away from the Earth when it finally formed. 71. 71. Gary Ansorge Says: March 13th, 2011 at 1:13 pm <#comment-367747> 70. Mike “I believe the moon was about 14,000 miles away from the Earth when it finally formed.” I doubt the moon could have coalesced within Roches Limit, ie, within about 5 planetary diameters(or about 40,000 miles). It would have been just a bunch of debris(but that would make for a pretty ring) http://en.wikipedia.org/wiki/Roche_limit Gary 7 72. 72. reidh Says: March 13th, 2011 at 3:23 pm <#comment-367789> The “fact” that the moon is in anyway constituted in orientation to the earth, suggests that the contrary might be true, this earth moon system being a binary one, I’m sure the center of it is not at the center of the earth’s mass, and therefore they both could be influenced by one another and subsequently seeking a new center of gravity from time to time, hence earthquakes in diverse places and not at regular intervals. 73. 73. Levi in NY Says: March 13th, 2011 at 4:25 pm <#comment-367802> Phil, what do you think of the prospects of using the far side of the Moon as a telescope site, since it wouldn’t be subject to radio interference from Earth? Would the benefit of not getting that interference be worth the project of building a telescope there? Are the craters sufficiently smooth and symmetrical that we could convert one into the dish of a radio telescope? 74. 74. David Says: March 13th, 2011 at 5:48 pm <#comment-367817> I want Google Moon CraterView. 75. 75. The Moon’s Got A Sexy Rearside. « OMEGA-LEVEL.NET - Says: March 13th, 2011 at 6:11 pm <#comment-367821> [...] Enlarge. | Via. [...] 76. 76. mike burkhart Says: March 13th, 2011 at 6:32 pm <#comment-367823> It is important to rember that it was only in the 1960s that we have seen the back side of the moon when a Russian lunar probe sent back a few blury photos.Bill O there are a number of theorys of the Moons origin: 1the Moon was part of the Earth and seperated.2 The Moon formed form matter left over from Earths formation3 the Moon formed somewhere else and was captured by the Earts gravity.4 A large object crashed into Earth thowing debri into orbit that collesed into the Moon. 77. 77. MichaelL Says: March 14th, 2011 at 9:46 am <#comment-368032> I don’t see the alien bases. Is this evidence of a cover-up? ;) 78. 78. DrBB Says: March 14th, 2011 at 12:15 pm <#comment-368074> @56 “<3 love <3 anchovies! Nothing tastier." Guess we'll have to agree to set up our personal lunar bases in different zones then. Me for the highlands around Mare Imbrium. Nice view from up there and the anchovie density is said to be quite low. Adding: appalled as I am to find myself in disagreement with a guy whose moniker refers to my favorite amateur-observational objects and an Aussie to boot. It’s like those Greek tragedies. A sad fate dictates that such an essential and irreconcilable difference must eternally divide those who might otherwise be friends. 79. 79. mike burkhart Says: March 14th, 2011 at 12:18 pm <#comment-368075> Oh I forgot the ridiculous theroy made by two Russian scientists and beleved by many UFO lovers : The Moon is Giant spacecraft that brought life to Earth from some other planet. There is no evidence to support this. In fact it kind of sounds like a Star Trek episode about the asteroid that was a spacecraft . It was called : For the world is hallow and I have touched the sky. 80. 80. Lasers, LRO and a Tarantula « Space « Science Today: Beyond the Headlines Says: March 17th, 2011 at 10:03 am <#comment-369385> [...] LRO also released a mosaic of the far side of the moon a few days ago. You can see the image, read more and compare it to the facing side on the Bad Astronomy blog in Discover. [...] 81. 81. Backside of the moon « Jerry Asher Says: April 2nd, 2011 at 4:26 pm <#comment-373506> [...] The Bad Astronomer posts an image from the Lunar Reconnaissance Orbiter. An explanation and an even bigger picture is available at his blog. [...] 82. 82. External Brain Storage » Pictures of the Moon Says: April 2nd, 2011 at 10:58 pm <#comment-373546> [...] http://blogs.discovermagazine.com/badastronomy/2011/03/12/the-extraordinary-back-of-the-moon/ [...] Leave a Reply Name (required) Mail (will not be published) (required) Website # * * About Bad Astronomy Phil Plait, the creator of Bad Astronomy, is an astronomer, lecturer, and author. After ten years working on Hubble Space Telescope and six more working on astronomy education, he struck out on his own as a writer. He's written two books, dozens of magazine articles, and 12 bazillion blog articles. He is a skeptic and fights the abuse of science, but his true love is praising the wonders of /real/ science. 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