Talk:The Blue Marble

message: Something that has always bothered me about this photograph:
Poles on a sphere are diametrically opposed to each other.  When you’re looking at a sphere, if you see one pole at the absolute bottom of the sphere, you should therefore see the opposing pole at the absolute top.
This photograph shows the South Pole very close to the bottom of the sphere; perhaps 15-20 degrees away from it, at most, since the absolute bottom still seems covered by Antarctica.  Therefore, I’d expect the top of the sphere to show more of the area closer to the North Pole - 15 to 20 degrees away from it – which, in this hemisphere, would be Siberia, or the northern reaches of Europe and Asia.  But the northernmost visible parts are Anatolia and the Caspian Sea – around 50 degrees away from the North Pole!
So to me, this picture looks almost as if the planet is “smaller” than it should be, relative to the sizes of the visible continents and oceans.  Compare to the topographic model seen here to see what I mean.
I wonder what’s the cause of this?  Is there an explanation, or am I simply looking at it wrong?
77.126.57.179 (talk) 16:02, 12 January 2009 (UTC)
replies: text: It's because it was taken close enough to Earth that significantly less than half of the planet was visible. Northern Europe was beyond the horizon, so to speak. You can see how this works by playing around with this Earth Viewer. You can reduce altitude (the box next to "Alt:") and watch features on the edge of the visible disk disappear as they recede over the horizon. --Cam (talk) 02:31, 13 January 2009 (UTC)
replies: text: Thanks - makes perfect sense now.  Seems that even from the Moon's distance (right above the equator), it's still somewhat apparent that some areas around the poles are beyond the horizon.  Not sure why I didn't think of it myself! 77.125.111.76 (talk) 16:38, 14 January 2009 (UTC)
replies: text: So if the image shows substantially less than a hemisphere, I think it shouldn't be called a "whole-Earth photograph" in the article. --Roentgenium111 (talk) 21:15, 7 December 2011 (UTC)
replies: text: Ah, so you'd expect a "whole-Earth photograph" to show frontside and backside at once, since it wouldn't be the "whole" earth otherwise? -- DevSolar (talk) 13:13, 16 December 2011 (UTC)
replies: text: Of course not, but I'd expect it to show essentially a whole hemisphere. Or would you call e.g. a 360° panorama photograph of the Earth from a balloon/airplane showing only a few square kilometres above the horizon a "whole Earth" photograph? --Roentgenium111 (talk) 19:10, 16 December 2011 (UTC)
replies: text: You don't get a whole hemisphere, ever. And I find a distance of 20.000 miles to be a good compromise between completeness and visibility. The impact of the picture was that what people had before were aerial or low-orbit photographs at best. Anyway, this is neither here nor there. It is called "whole earth photograph", and what you or I think about that term simply doesn't matter in WP terms. -- DevSolar (talk) 09:03, 19 December 2011 (UTC)
replies: text: I know you can't get a perfect hemisphere, ever, that's why I wrote "essentially". But this photograph isn't even close to showing a whole hemisphere, as the OP pointed out - it shows only maybe two-thirds of a hemisphere (which is of course still much better than any previous photos - but a picture e.g. taken from the Moon would be substantially "better"). And "in WP terms", the sentence containing the "whole-Earth photograph" claim in the article has been tagged as unreferenced, and the caption of the image as quoted in the article does not in fact use this word. --Roentgenium111 (talk) 14:22, 19 December 2011 (UTC)
replies: text: *Sigh*. Whole-earth photograph, not whole-hemisphere photograph. The point being that the planet earth as a whole is pictured, from horizon to horizon, and not just a section of its surface. The blue marble, as opposed to a square of surface. I find this discussion highly irritating. -- DevSolar (talk) 14:27, 6 January 2012 (UTC)

text: *:Ksjejd 2600:6C58:763F:28D3:303B:B003:C7EB:ED17 (talk) 02:35, 8 December 2023 (UTC)
thread_title:  Why Isn’t More of the Northern Hemisphere Visible? 

message: Does anyone know what film this image was recorded on, I am assuming Eastman Kodak Kodachrome; any ideas?  —Preceding unsigned comment added by 74.69.118.128 (talk) 06:31, 23 April 2008 (UTC)
replies: text: The film was called "Ektachrome MS, color reversal, ASA 64" according to NASA. --Cam (talk) 06:51, 23 April 2008 (UTC)
thread_title:  Photographic Medium 

message: I am an adjunct instructor in geosciences and a licensed land surveyor.  My class in water resources used several methods to calculate the actual distance Apollo 17 was from Earth when this famous photo was taken.  Available on the internet are pages of the full-frame Hasselblad images from this mission, so it is easy to print the full-frame image to the exact scale as the negative (Hasselblad images are 6 cm by 6 cm on the 70 mm film) and then to measure the pole-to-pole size of the Earth on the printed-to-scale copy of the negative.  On such, the Earth pole-to-pole is about 31 mm in diameter.  We know that the lens had a focal length of 80 mm and we know that the pole-to-pole diameter of the Earth is about 7,900 statute miles.  Therefore, using similar-triangle geometry, the distance, X, is calculated as X/7900 miles = 80 mm / 31 mm, or X = about 20,400 statute miles to the center of the Earth.  The log of Apollo 17 voice communications is also on the web, with the photo numbers inserted very closely to when in flight they were taken.  Shortly after the Blue Marble was exposed, probably by Schmitt, Houston FIDO relays a distance of 18,100 nautical miles (multiply times 1.15 for statute miles).  All things considered -- log, photogrammetric measurements, etc. -- coupled with uncertainties in all methods, led our class to conclude that the distance should be stated as about 20,000 statute miles from Earth.  It makes little sense to try to be more precise, and it is interesting in the voice log that Schmitt and Houston some minutes later talk about being at about 20,000 nautical miles (I insert "nautical" because that is my understanding of the aviation standard for miles)and Schmitt replies "It feels like about 20,000 miles."  From the voice log is a lot of environmental-conscious dialog about the views the Apollo 17 crew are seeing around the time of the Blue Marble photo, and maybe some of these should be on the Blue Marble page as well.
Rjwoodbury 20:41, 31 August 2007 (UTC)
replies: text: Hi, this is interesting stuff. I think the distances given in the Apollo transcripts may refer to distance to Earth's surface rather than to its center, which may suggest a revision of your estimate. Also note that at these relatively small distances from Earth, you are not able to see a full hemisphere, so the diameter of the visible part of the Earth will be less than the Earth's full diameter. --Cam 02:11, 1 September 2007 (UTC)

text: Hi, this is great! If NASA corrects the figure, let us know and I will definitely edit this article accordingly. I was just comparing the distances and times mentioned in Eric Hartwell's provisional Apollo 17 flight journal with those for Apollo 12 and other missions at the NASA History Division site, and based on the probable Ground Elaped Time (GET) of the photo of about 5 hours, came up with a probable figure of 15,000 to 16,000 nautical miles (17,300 to 18,400 statute miles) from Earth's surface. So we're converging around a similar figure. Of course, we can't add our original research to this article, but again, if NASA publishes something along these lines I will certainly add it to the article. --Cam 03:44, 4 September 2007 (UTC)

text: My calculations (correct me if I'm wrong) based on this specification: Max. Aperture 2.8 Focal Length 80.5mm Diaphragm 2.8-22 Angle of View, Diag./Horizontal 52°/38° No. of Elements 7 T* Focusing Range 3 ft-infinity (0.9m) Weight 1 lb 2 oz (510g) Length 2 9/16 in (65mm) Filter Æ 60 would suggest that a distance of 12145.25 km above the Earth's surface would be the minimum distance required to capture the entire Earth in to the angle of view. Veritatis in lege (talk) 22:47, 18 June 2015 (UTC)
thread_title:  Photogrammetric distance calculation: 

message: I found this on digg. Maybe it should be in the article?
http://visibleearth.nasa.gov/view_detail.php?id=7100
:Well, the torrents are linked from , which is one of the first links on , which is linked from the article. ¦ Reisio 21:27, 4 February 2006 (UTC)
thread_title:  NASA torrents for blue marble : next generation 

message: *I love the picture 'The Blue Marble'. It's even on my talk page (User Talk: Abyab)
--Abyab 16:04, 14 May 2006 (UTC)
thread_title:  Love 

message: I read somewhere else on wikipedia (searching for page) that the original of this image is actually the other way up, because of the spacecraft's path/orientation, and was merely rotated for publication so as not to confuse. If someone can find before I do whether this is true, perhaps a note would be useful, if we're showing it "upside down". There is no reason North should be at the top, even on a map, after all, much less a photograph. Graldensblud 12:10, 2 November 2006 (UTC)
replies: text: There's a very good reason to have North at the top, on maps and on this photograph: convention.  I think that the optimal response to this entire debate is to note the original orientation in the article but maintain the picture in the orientation it was published in. Ari 12:45, 2 November 2006 (UTC)

text: I disagree. Not only is it an interesting fact that they were rotated 180degrees, but as to the poster above states, it gives a wonderful observation of what the astronauts may have felt 20,000 miles from home, and 'upside down'. Leave it the way it is - The 'correct image' as an addition is fine. Wikipedia at it's best. ~Daniel
I agree with sæ about moving the original photo higher on the page; it's the original one. And If you don't mind I'm changing "upside down" for "the south pole was at the top" as there's no "up" or "down" in maps, it is only a convention and it depends on the position of the viewer.--Autusgo (talk) 02:35, 23 June 2010 (UTC)
thread_title: Upside down?

message: If you carefully read the reference cited, you should agree that the page should not have been changed to say Cernan likely took the picture.  The reference actually makes the best case for Schmitt having taken the picture, and specifically mentions that Cernan was the LEAST likely to have taken it.  "Can you see it, Jack?" appears to be Cernan asking Schmitt, who now has the camera and now with the 80mm lens, if the Earth is visible on his side of the capsule.  Click, click ...  Could someone who can edit the main page check on this and perhaps change it back.  Thanks.  —Preceding unsigned comment added by 206.159.164.195 (talk) 16:19, 5 December 2007 (UTC)
thread_title: Who took the picture?

message: Apollo 17 was presumably accelerating away from the Earth at the time the photo was taken (a couple of hours after leaving Earth orbit), so presumably the capsule was pointing towards the Moon and the command module engine was pointing roughly towards the Earth. Looking at the incline of the capsule wall containing the observation windows it would seem impossible to see the Earth at that point. Am I missing something really obvious?  eg was there a period of time after leaving Earth orbit, but before starting the long burn towards the Moon, when the craft was rotated?  — Preceding unsigned comment added by 82.44.28.101 (talk) 07:50, 5 April 2012 (UTC)
replies: text: Yes, you are indeed missing something obvious. A spacecraft is not like an airplane; there is no air in space and so absolutely no reason why it has to "fly" nose-first. It can be pointed in any direction desired. When the astronauts want to photograph the Earth, they will naturally orient the craft so that the Earth is visible out their windows. And for purposes of communication, it is necessary to keep the high-gain antenna, located at the back of the Service Module and generally pointed forward, pointed back at the Earth. For most of the time en route, the craft is subject to solar heating, so they would chose an optimum orientation for passive thermal control (known colloquially as "barbecue mode"), where the craft would slowly roll to prevent the sunward side from getting excessively hot and the shadowed side excessively cold. JustinTime55 (talk) 16:46, 5 May 2016 (UTC)

text: The acceleration phase (Trans-lunar injection or TLI) only took a couple of minutes. (Apollo 8 needed 318 seconds. However, since they had no Lunar Module with them, the total mass they had to accelerate was reduced. On the subsequent missions the payload was about 1.5 times as heavy. Thus we can estimate that Apollo 17's TLI phase took about 8 minutes.) After burn-out, being on injection velocity, they had to turn the Command/Service Module backwards in order to dock it to the Lunar Module and pull it out of its packaging (SLA). (On the Apollo_11 mission this was done half an hour after TLI.) Then they sent the 3rd rocket stage a signal to shoot itself away onto a kind of junk disposal orbit. The ship would remain in this Earth-directed position till close to the Moon since its rocket engine was then needed to slow it down into Moon orbit. Thus the crew had an excellent view back at the Blue Marble while on their way. --Liberatus (talk) 01:55, 13 December 2012 (UTC)
thread_title:  How was it possible to take the shot? 

message: Has anyone else thought about how misleading the 2012 blue marble looks? The picture makes it look like North America (and especially the USA) fills up a huge chunk of the surface of the Earth  while in reality, it is not nearly as big as the picture suggests. While I know some people will realize this I can't help but feel like NASA intentionally did this this to put the USA in focus of the picture to appeal mostly to it's native nationality - this, to me, ruins the purpose of the blue marble pictures as a set of images to encourage global brotherhood. Thoughts? SorteKanin (talk) 09:06, 12 May 2015 (UTC)
replies: text: Yes, I noticed the same thing.  The image appears out of scale to me.  I confirmed that this is indeed the original image that NASA publicly distributed. The only information I could find was that this is a composite image. I did not think for a moment that this is a conscious choice by NASA to appeal to Americans' pride. I just thought that the scale was wrong.  I used Google Earth to view (a model of) earth from approximately the same angle, and the results confirmed my intuition. The view I was getting was quite different to the image (in terms of continental scale).  --Aboulis
I read the excellent discussion in this page and I realised that altitude matters. The Earth Viewer tool that user Cam linked above is very useful. I played around a bit to get a feel of different altitude views. You can notice, that if you are using a low altitude (say 1,000Km), the globe appears quite distorted. This is because you are getting a small part of a hemisphere, yet you project it onto a whole hemisphere. It is as if you are viewing this part of earth's surface through ultra wide lens. I assume that something similar is happening with Blue Marble 2012 too. Playing around with Earth Viewer, I think that Blue Marble 2012 resembles a picture produced by Earth Viewer's model from around 2,000-2,500Km altitude. In reality, we would not be able to see the whole earth from this altitude, or at least not see it occupying a similar section of our field of view as we see it on a computer monitor. Hence the feeling of distortion. Doing some quick calculations I found that you would need to be at 11,000Km-17,000Km away to see the whole earth within 40°-30° of your field of view (or in other words to capture the whole earth with a normal lens photo) Aboulis (talk) 04:18, 23 May 2015 (UTC)
thread_title: Blue Marble 2012 misleading

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thread_title:  External links modified 

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thread_title:  External links modified 

message: Every photographer with a 35mm camera, which takes rectangular 36×24 mm photographs, will often turn the camera on its "side" to take pictures. The most common reason is to take a full height photo of a person. They might rotate clockwise or counterclockwise on the same roll of film. No one ever says "the photograph shown above was as the photographer saw it" and then displays the print of the shot of the person with their head to the right and their feet to the left. Nor would they ever say, "but it was largely distributed with the image flipped to fit expectations of heads-up orientation". There must be millions of printed newspaper and magazine images where this is true. 
The same is true of this picture. If there were photos of astronauts on this roll, then when printed, the prints would all be rotated to put the images in a heads-up orientation, even if they were heads-down on the roll of film, and no one would ever comment on it. All roll film has a "top" and a "bottom" as it goes through the camera, because all film cameras were built with a top and a bottom. But on Earth, as in space, almost every roll of film will have images whose obvious top does not align with the top of the roll of film. This is never noteworthy, because when the print is viewed the viewer rotates the print to place top up. The same is true of this image.--Nick Beeson (talk) 21:58, 14 September 2018 (UTC)
thread_title:  Upside down 

message: Among the several versions of the photo, this version has what seems to be a black object on the top left, maybe just off the coast of Africa. Does anybody know what object that might be? And would it be right to assume that this has been manually removed from all other versions of the photo?
-- Nungee (talk) 09:23, 25 October 2018 (UTC)
thread_title:  What is the black object on the original(?) photo? 

message: The most eminent feature of the "Blue Marble" photo, the image uniformity, is not discussed in the literature, not even mentioned. The earth's image includes large areas of gas-phase – clouds, liquid-phase – oceans, and solid-phase – land, and the uniformity is nearly true for each phase separately. This feature is not compatible with Lambert's cosine law. One photo – a thousand theories. Urila (talk) 18:50, 20 October 2020 (UTC)
replies: text: Yes, and? You are citing your own publication, that additionally has not been peer reviewed. I'm not sure what you're evening wanting here, but if it's to add this to the article then no. Original research is not permitted. — Huntster (t @ c) 16:55, 14 August 2020 (UTC)
thread_title:  The Blue Marble image is uniform 

message: The article Timeline of first images of Earth from space states that the image of Earth from space taken by a person was taken during the Apollo 8 mission on December 21, 1968. The citation can be found here: https://en.wikipedia.org/wiki/Timeline_of_first_images_of_Earth_from_space#cite_note-34
Or is this article distinguishing between a picture of a fully illuminated and a partially illuminated Earth? If so, then it should make this clear because as it is now, it is misleading. Shahall (talk) 20:25, 3 November 2022 (UTC)
replies: text: , and thank you for both noticing and reporting this major text correction. Randy Kryn (talk) 20:49, 3 November 2022 (UTC)
thread_title:  Not the first image of the face of the whole Earth taken by a human 

message: The coordinates could be added at least to the nearest whole degree over which the photo was taken. B137 (talk) 06:32, 22 May 2023 (UTC)
thread_title:  Coord missing 

message: The original image of the Blue Marble had the South Pole to the north. Unfortunately, the image is often rotated to the north, as here, so that the North Pole is on top again. But that destroys part of the beauty of the original image: that we shouldn't take ourselves so seriously and that the Earth is just a drop frozen on the surface, rushing through the vastness of space. Therefore, it is important to use the original image, not the rotated one, in the Wikipedia article. 80.71.142.166 (talk) 08:27, 20 August 2023 (UTC)
thread_title:  Upside down 

message: The first paragraph in the Context section suggests that The Blue Marble is the second time an image like it was taken by a person since 1968's Earthrise image. I understand that a distinction is being made between fully illumined and partially illuminated images of the Earth. However, the Earthrise image clearly shows a partially illuminated Earth. So realistically The Blue Marble should be the first image of a fully illuminated Earth taken by a person. Not the second. Jimisticks (talk) 19:27, 4 December 2023 (UTC)
thread_title:  Confusing language in the first Context paragraph 

message: I would have thought that these images would be a priority and of interest to everyone on earth. 2A02:C7C:5E90:7D00:5471:FA2C:410C:8E77 (talk) 09:22, 22 January 2024 (UTC)
replies: text: In the case of Webb, Earth is in the direction of the Sun, which is bright enough to destroy the instruments. The Webb spacecraft has to keep its sun shield between its instruments and the Sun. Webb also never has the Sun behind the Earth (i.e., an eclipse), as it moves around the L2 point in an oval several times the diameter of Earth. Having constant sunlight, rather than moving in an out of Earth's shadow, helps keep the spacecraft's temperature as uniform as possible, which is good for a lot of reasons. In contrast, Hubble does get pointed at Earth once in a while for calibration (https://astronomy.stackexchange.com/questions/26041/has-the-hubble-ever-been-pointed-at-earth). DKMell (talk) 07:38, 15 March 2024 (UTC)
thread_title:  Why hasn't Hubble or Webb telescopes ever taken a photograph of earth? Why is the original blue marble image taken from the moon out of scale and way way too small? 

message: Why are all the images on here photoshoped and not the real image? 79.106.203.15 (talk) 09:23, 14 March 2024 (UTC)
thread_title:  Wrong image 

message: The Earth in this image is a bit taller than it is wide. Is that because we're missing a bit of the Earth on the right side because of darkness? Or did the image get stretched slightly at some point? DKMell (talk) 07:41, 15 March 2024 (UTC)
thread_title:  Non-circularity 

message: The actual orginal South at the top one shouldn't be buried halfway down the page TheBrodsterBoy (talk) 02:02, 28 April 2024 (UTC)
thread_title:  Can we not put the 'wrong' image at the top just cause it's more common? 

message: was looking over this page, and noticed in the original photograph/officially-designated "AS17-148-22727" there was a black dot (probably dust?) near africa that wasn't present in the other "corrected" images, specifically File:The_Earth_seen_from_Apollo_17.jpg and File:The_Blue_Marble_(remastered).jpg. Checking out "AS17-148-22726", it does not have that (and so does 22725) and that was probably used instead, especially given the article mentions that -22726 and 22727 are used interchangably for the image. However, the metadata for the images indicate that they are derived from 22727 whilst not having that black dot + the article opening says "the original 22727" against what is possible 22726. Saying that 22727 is the original raw photograph but then using the edits onto a different photograph means this is inaccurate. Although it seems like other sources also name the canonical image but then use a different one so this is an extremely common error? 41.193.239.110 (talk) 13:14, 18 May 2024 (UTC)
thread_title:  confused about whether corrected images are -22726 or -22727