Talk:The Blue Marble

Why Isn’t More of the Northern Hemisphere Visible?

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)

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)

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)

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)

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)

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)

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)

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)

• 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)

  Ksjejd 2600:6C58:763F:28D3:303B:B003:C7EB:ED17 (talk) 02:35, 8 December 2023 (UTC)

Photographic Medium

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)

The film was called "Ektachrome MS, color reversal, ASA 64" according to NASA. --Cam (talk) 06:51, 23 April 2008 (UTC)

Photogrammetric distance calculation:

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) - Randy J. Woodbury, MS, LS, adjunct instructor in geosciences at SUNY Fredonia, rjwoodbury@yahoo.com, August 31, 2007

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)

Yes, I agree the Mission Control communication likely refers to Earth's surface. My mention of center is only that the rough photogrammetric calculation would be to the center of a line that is nearly a pole-to-pole diameter. I agree that at 20,000 miles the full 7,900 mile diameter would not be visible (I calculate that the visible tangent-to-tangent points near the poles would be a line less than the full diameter, at about 7,700 miles, and some miles closer to the Earth's surface from its center). It would have been nice if there were 10 mm by 10 mm tick marks as on the lunar surface photos, except that it would detract from the artistry of the image, to help determine the size of the Earth on the negative more accurately. I think I'll work on this a little more, and I appreciate the constructive feedback and tentative agreement that our class thinking might be valuable in analyzing the Blue Marble nearly 35 years after it was clicked on a Hasselblad space camera. Rjwoodbury 18:47, 1 September 2007 (UTC) RJWoodbury

Working with data points given by the Public Affairs Officer (apparently as provided by FIDO, the Flight Data Officer) on the Hartwell transcript of real-time voice conversations during the relevant portion of the Apollo 17 mission, I made graphs of range and speed versus time of the spacecraft for the period bracketing the Blue Marble photograph taken at about 306 minutes into flight. From these graphs, I can quite accurately interpolate the range and speed at 306 minutes to be, as converted from the transcript units of nautical miles and feet-per-second, to have been 18,000 statute miles from the Earth's surface and traveling away from the Earth at about 10,500 statute-miles-per-hour (or about 175 statute-miles-per-minute). Further researching on the Hasselblad EL image size on the 70 mm film led me to find that the image was not the full 6 cm but likely about 56 mm (and the Hasselblad lunar surface cameras had glass plates at the film plane, for the 10 mm by 10 mm grid marks, that limited the full frame image to 54 mm). So, for a better photogrammetric analysis, the image of the Blue Marble on the actual film is likely about 29 mm rather than my first-calculated 31 mm. Further, a chord connecting the line-of-sight tangents near the poles in the photograph would be about 7,700 miles long and this chord at its center point would be 800 miles nearer the Earth's surface (closer to the Apollo 17 spacecraft) than the Earth's center. This leads to the photogrammetric equation, as previously discussed, to be more accurate as: ( 80 mm / 29 mm * 7700 statute miles ) - 3150 statute miles = 18,100 statute miles for the photo-calculated distance from the Hasselblad lens to the point on the Earth's surface shown at the center of the Blue Marble. In summary, my class and I have used interpolations from graphs of NASA-stated data on Apollo 17's range and speed near the time of the Blue Marble picture, along with photogrammetric measurements and analyses of the full-frame scanned image of the Blue Marble, to determine that an accurate statement of the distance Apollo 17 was from the Earth's surface at the time of the famous Blue Marble photograph was about 18,000 Statute Miles (or about 29,000 kilometers). We believe that the often-stated distance of 45,000 kilometers, and the occasionally-stated distance of 40,000 kilometers, stand to be corrected based on our analyses. The distance should be stated as "about 29,000 kilometers or about 18,000 statute miles." Rjwoodbury 17:22, 2 September 2007 (UTC)

I just received an email from the NASA contact at the Reference 1 NASA web page that gives us the distance on the article main page. This is what the email says, in part: "Although, I am not a scientist (I am just a data visualizer), I have validated your calculations and have determined that you are correct. The entry should read '...about 20,000 statute miles from the center of the earth.' I will make the appropriate changes." And this, in part, was my reply, with thanks: " Thanks for laboring on this on Labor Day. At Wikipedia, we've been discussing this over the last few days, and I have refined the analysis. Attached is the full discussion with the concluding recommendation: The distance should be stated as ' about 29,000 kilometers, or about 18,000 statute miles, from the surface of the Earth at the image’s center near Madagascar. ' " I'd like to thank user Cam and NASA for helping to make Wikipedia a more reliable encyclopedia. When NASA makes the change to its page, could someone make the appropriate similar change to the Blue Marble article where it cites the NASA page for the distance? Rjwoodbury 17:04, 3 September 2007 (UTC)

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)

NASA corrected their web-published distance, cited in Reference 1, to "about 18,000 statute miles away from Earth" on September 4, 2007. I changed the distances in the article to correspond to this cited and corrected reference authority, and updated the date of retrieval for the referenced web page. Best regards to all in this process. Rjwoodbury 17:05, 4 September 2007 (UTC)

Final note, for the record: before user Cam and the rest of us worked on re-checking the actual distance, the NASA reference cited in the article listed the distance as 28,000 statute miles rather than the now-corrected 18,000 statute miles. Using the former web-published NASA distance, The Blue Marble Wikipedia page accurately cited the older source at 28,000 miles or 45,000 kilometers. As of the September 4, 2007, NASA change to the referenced web page, the NASA source and the Blue Marble article now list the distance as corrected. The old distance cited of 28,000 statute miles may (approximately) refer to another set of Earth photos taken by Schmitt later in the flight, but these are not the famous Blue Marble, as the Earth is both much smaller on the Hasselblad film for these later photos and not as fully illuminated as the Blue Marble photo. Of special interest, Dr. Schmitt is now the chair of the NASA Advisory Council for planning the next human missions to the Moon -- future chances for human-made Blue Marble photographs. Rjwoodbury 02:59, 5 September 2007 (UTC)

The article states: "Apollo 17's late-day (EST) December launch meant that the spacecraft passed over Africa during daylight hours in Africa;"

but shouldn't "late-day" be changed to night? It was launched at 05:33 Universal Time according to:

http://www.spacefacts.de/mission/english/apollo-17.htm

• It shouldn't be changed to night, 5:33 is late-day.

--Abyab 16:06, 14 May 2006 (UTC)

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I have seen a distance figure of about 25,000 miles or 40,000 km for this photo in several places. --Cam 05:12, Jan 18, 2005 (UTC)

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After editing distance to 40,000 km, found a NASA reference for 28,000 miles so I changed it to 45,000 km. Also found a NASA cite for the time of the photograph (5 hr 6 min after launch ~ 10:39 UTC). --Cam 17:21, Jan 21, 2005 (UTC)

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)

File type?

When I downloaded the "very high res" pictures in the links, I couldn't view the files. They have no file extension after their names. Maybe instructions can be added to view the files...

         The file is compressed using gzip which is an open source compression application that can be found at www.gzip.org

wemzhou shi

Why is the photo displayed incorrectly? The original photo has the southern pole at the top (e.g. "upside-down"). See the original here: http://www.lpi.usra.edu/resources/apollo/catalog/70mm/magazine/?148 --24.137.104.16 17:54, 21 July 2005 (UTC)

Define "correctly". Aren't most humans used to seeing the north pole at (or toward) the "top" of the planet? It would make sense, then, to display the image in an orientation that has the "top" of the planet at the top of the image. —HorsePunchKid→龜 23:33, July 21, 2005 (UTC)

This is the way NASA has released it. No point in changing it. ¦ Reisio 02:01, 2005 July 22 (UTC)

The photo is upside down. I purchased a copy of this image as a poster from NASA and it has the south pole at the top. Take a look at the link I provided; it has the original orientation of the prints from the film cartridge. --24.137.104.16 23:24, 10 August 2005 (UTC)

Original Caption

One of the problems with open-source material is that "original" seems a maleable concept. The wikimedia version of the caption for this photo reads Malagasy, while my read of the NASA reference is Madagascar. Which is it and what is our intention (publishing the original "Original" or the open-source and therefore maleable "Original")?—Gaff ^ταλκ 09:05, 7 November 2005 (UTC)

• Most consistent "original" appears to be:

View of the Earth as seen by the Apollo 17 crew traveling toward the moon. This translunar coast photograph extends from the Mediterranean Sea area to the Antarctica south polar ice cap. This is the first time the Apollo trajectory made it possible to photograph the south polar ice cap. Note the heavy cloud cover in the southern hamisphere. Almost the entire coastline of Africa is clearly visible. The Arabian Peninsula can be seen at the northeastern edge of Africa. The large island off the coast of Africa is the Malagasy Republic. The Asian mainland is on the horizon toward the northeast.

NASA torrents for blue marble : next generation

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 [1], which is one of the first links on [2], which is linked from the article. ¦ Reisio 21:27, 4 February 2006 (UTC)

Love

• I love the picture 'The Blue Marble'. It's even on my talk page (User Talk: Abyab)

--Abyab 16:04, 14 May 2006 (UTC)

I agree. It is a beautiful and quite moving photo of a wonderful planet. — Preceding unsigned comment added by 108.23.105.146 (talk) 06:15, 12 March 2013 (UTC)

Size of the earth

Earth is said to have the appearance of a child's marble in the photo; that is the Earth has the same aspect at this distance as a child's marble at about arm's length.

I resurrected this from the archive. The astronauts were far enough away from earth that the earth was the size of a marble, held at arm's length. In other words, take a child's marble, and hold it in front of you. What the astronauts saw was a tiny earth which would have been eclipsed by a marble. --Ancheta Wis 08:47, 21 June 2006 (UTC)

Maybe I'm doing the math wrong, but I figure that the Earth subtends about 16 degrees at 28000 miles. If you clench your fist and stretch out your arm, your fist is about 10 degrees wide.[3] So the Earth could not have been eclipsed by a typical marble held at arm's length. --Cam 14:45, 21 June 2006 (UTC)

Your arithmetic is correct. The "size" reference has been removed from the lead-in. mdf 18:43, 14 September 2006 (UTC)

Surely it's supposed to be way bigger than a marble. The moon looks several times larger than a marble from 365 000 km away, why would a bigger Earth seem smaller for closerby ? --SonicX 0:40, 6 September 2006 (GMT+2)

Wrong caption?

Hi, as far as I know the name "Blue Marble" refers to NASA's cloudless composite satellite image of the whole Earth surface, the one accessible via this link (also provided in the external links section of the article): [4]. And I was expecting to find an article about that when I typed that in the Wikipedia search bar. Is everyone sure that this is in fact the correct name of the Apollo 17 photo? Regards, Atilim Gunes Baydin 19:49, 7 October 2006 (UTC)

Yeah, the title thing has made me a bit uncomfortable, too. I have been interested in this photo for many years, but never heard it called "The Blue Marble" until I saw this article. I'd heard people call the Earth itself a blue marble, but not this particular photo.

Sometimes Wikipedians give new names to things that don't have real-world names, or that only have obscure names. The actual correct name of the photo is the number that appears in the article. But I doubt an effort to move the article to AS17-148-22727 would succeed. --Cam 05:18, 8 October 2006 (UTC)

The name goes back to at least 1995, which probably pre-dates the Visible Earth stuff at NASA. Going further may require a trip to a real library, to look for instances of its use at the time it was originally published. mdf 13:49, 11 October 2006 (UTC)

Upside down?

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)

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)

Is there any way that we can get a comparable, higher-resolution version of the original, "upside-down" image? And perhaps move it higher up on the page? While I don't think the pre-distribution rotation of the image needs more than the present mention in the text, users may find the image itself compelling. Personally, I think it best captures the truly unconventional sensation the Apollo 17 astronauts must have felt. sæ (talk) 06:50, 20 January 2008 (UTC)

I think the caption of the original, upside-down, photograph should be changed to say that "the south pole was at the top" of the picture, without referencing the north pole which is absent from the image. Also, the second appearance of the original photograph at the end of the article is redundant and should be removed. Chen. —Preceding unsigned comment added by 89.138.107.93 (talk) 08:08, 1 March 2008 (UTC)

I dont think we need to have a north-corrected and uncorrected photo. they are the same bloody photo. naturally enough you will have the same problem when you use your own camera in portait . the resulting file will default to landscape, so then you rotate it back to portrait 202.92.33.210 (talk) 05:34, 15 August 2008 (UTC)

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)

How can a photograph be inherently upside down? Wouldn't it depned on how you hold it? The ones with the pole on top or bottom are equally the original, so what is the point of having both? —Preceding unsigned comment added by 205.193.96.10 (talk) 17:26, 26 November 2010 (UTC)

Who took the picture?

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)

Fixed today per the above observation. Indeed, Reference Citation No. 4 makes the case that Schmitt is the most likely to have been the photographer and Cernan the least likely.Rjwoodbury (talk) 00:47, 9 December 2007 (UTC)

Where's the picture

The link appears to be broken

How was it possible to take the shot?

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)

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)

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)

Blue Marble 2012 misleading

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)

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)

I reached out to the creator of the image Norman Kuring, describing what I have found and asking him the following questions: Can you please tell me how you created the composite? In particular, what altitude is it supposed to simulate, and what kind of lens? Do you agree that if the human eye is our only viewing tool, it would be impossible to get a similar view (at any distance from the earth)? If Norman replies I'll update this page. Aboulis (talk) 04:18, 23 May 2015 (UTC)

Norman replied and he confirmed my thoughts. The gist is that the image was created using a near-sided perspective projection with the viewing point placed 2100Km above 20° North by 100° West. This projection results in a very wide-angle presentation such as one might get with a fish-eye lens. This explains the results quite well and you can use Earth Viewer to confirm it. He also gave me permission to use his reply here. This is the full reply (edited only to convert web url links to wikipedia style links):

Here follows a brief outline of how that image came about.

On January 19, 2012, Suomi-NPP Project Scientist, Jim Gleason, asked a colleague of mine, Kevin Turpie, if he had an updated ocean color image that Jim could use at the American Meteorological Society meeting in New Orleans the following week. Kevin passed the request on to me, and I set about downloading and processing VIIRS chlorophyll concentration measurements. By the following day it became clear to me that my jobs would not finish in time for the conference, so I decided to try my hand at a true-color VIIRS composite which I had not attempted before. I knew that VIIRS orbits overlapped, and this allowed me to make a single-day composite without inter-orbit gaps. The request was for a meeting in New Orleans, so I looked for a day that that city was cloud-free and a day that had a goodly amount of cloud-free coastal waters exhibiting ocean color features. The data for January 4, 2012 looked promising to me.

Now, VIIRS is a non-tilting ocean-color instrument and therefore suffers heavily from sun glint contamination. The fact that I picked January helped since most of the glint would be in the southern hemisphere. Nevertheless, to avoid distracting glint streaks in my image, I would need to limit my coverage to mostly the northern hemisphere. I also could not include the arctic regions of the planet because the Arctic is dark in January. I still wanted to present the imagery "in the round", so I opted to use a near-sided perspective projection from an altitude of just over 2100 kilometers above 20 North by 100 West. This projection results in a very wide-angle presentation such as one might get with a fish-eye lens. If you are looking for a more "realistic" way to view it, you could display it on something like the hyperwall that NASA uses and stand close to it -- turning your head to view the horizon in various different directions.

Jim Gleason used the image in one of his AMS talks, but he also passed it off to the NASA Public Affairs folks who started to hype it up to the point that it went viral. Jim or someone in Public Affairs conferred the moniker "Blue Marble". Over the next few weeks, I was continually amused by internet comments deriding the impossible view or the jingoistic attitude of NASA. (Mexico has a more central role in this image than the United States, and I often feature non-US regions in images I make e.g. http://earthobservatory.nasa.gov/IOTD/view.php?id=85764 , https://www.flickr.com/photos/gsfc/16094149559/ , http://earthobservatory.nasa.gov/IOTD/view.php?id=85514). I was also amused by this cross-over use of the data for a comic strip.

I hope this helps.

— Norman Kuring

Aboulis (talk) 15:34, 2 June 2015 (UTC)

Thanks for the info, very interesting. I still frown upon the picture's skewed scale though. I hope a future Blue Marble shot will be more fair to the rest of the world. SorteKanin (talk) 13:32, 14 July 2015 (UTC)

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Upside down

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)

What is the black object on the original(?) photo?

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)

The Blue Marble image is uniform

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)

Urila (talk) 13:26, 14 August 2020 (UTC)

References

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)

Not the first image of the face of the whole Earth taken by a human

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)

 Done, and thank you for both noticing and reporting this major text correction. Randy Kryn (talk) 20:49, 3 November 2022 (UTC)

Coord missing

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)

• Just like how ISS shots and videos include coordinates etc. B137 (talk) 16:56, 31 July 2023 (UTC)

Upside down

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)

Confusing language in the first Context paragraph

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)

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?

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)

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)

Wrong image

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

Non-circularity

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)

Can we not put the 'wrong' image at the top just cause it's more common?

The actual orginal South at the top one shouldn't be buried halfway down the page TheBrodsterBoy (talk) 02:02, 28 April 2024 (UTC)