It is one of the most famous and iconic photographs ever taken, an image that was reproduced on countless newspapers, magazines and websites. It has been dissected and discussed many times. It is AS11-40-5903, seen here in a version stored at the Project Apollo Flickr Archive:

What I want to focus on here is a small detail seen in the visor, and I’ve zoomed in here to the version seen on the front cover of Life Magazine, using my own copy:

The small detail in question is the little blue dot left of centre of the visor. The dot has been identified as Earth before, but what I want to do is just give a little more back up data to the idea that this is what we are seeing.

So, the first thing we need to find out is where was Earth at the time the image was taken? We know what time that was, because it is recorded in the ALSJ here, and if we skip through this youtube video to the relevant points, we can see the moment where it was taken. Below is a the moment (left) when the image prior to this one in the magazine was taken on the right is the moment Neil takes this famous photo.

As you can see, Buzz moves out of shot of the TV camera between photos, so let’s check that we have Neil in the right place before we do anything. Before we do that, we need to reverse the visor view so that the mirror images what we can actually see.

Neil has moved to a position in line with the engine bell, roughly the same point reached by Buzz’s shadow.

If you follow the video from the point where 5902 is taken to the point where Neil reaches the place where he takes 5903, you can see the top of Buzz’s shadow move to that position as he goes off camera.

The position of the solar wind experiment to the right of Buzz’s shadow seems incorrect, but here we are at the mercy of perspective being distorted by the curve of the helmet.

GoneToPlaid has done some excellent work here that demonstrates the impact of the visor curve on the image.

To a certain extent I am replicating his work, but I refer to it only in passing - I am working on it independently and coming to my own conclusions.

You can also do that if you have any issues with what is being presented here.

The key information here is that Earth is at an angle of just over 272 degrees from north (just past due west), and at an angle above the horizon of just over 59 degrees.

First things first, is Buzz facing the right way? Well, here’s the LRO’s view of the Apollo 11 landing site, together with the positions of Neil (N), Buzz (B) and the direction towards the Earth shown by the green arrow.

Now that we know where the two respective people were stood, we can try and work out whether Buzz was indeed looking at Earth in the distance.

As we know when the photograph was taken, we can use astronomy software to see where Earth would have been in the sky at that time, as well as the sun. I use Stellarium, and right is an image based on a time of 04:15 on 21/07/69.

A bit of head tilting should tell you that this would put Earth somewhere over Neil’s left shoulder, or right from Buzz’s perspective, and if you head on up to the visor photo you’ll see that this is indeed where it is.

The next thing is to see if it’s in the right place in the visor. To do that we need to reconstruct the TV view of the scene to show where Buzz was. I’ve done this by superimposing an earlier shot showing the scene to the left of the LM, and a version of Buzz taken from the flag ceremony, added in roughly the right place.

After that, it’s a simple job to use a protractor to draw a line at 59 degrees from the horizontal:

Seems that 59 degrees places the Earth quite high in the sky - so there is absolutely no problem there with it being in the top of Buzz’s curved visor. Is there a way of checking whether that angle is correct?

Well, we can get some verification from other images taken around the LM, specifically one showing the Earth, an Earth with time and date specific weather features.

Above left we have AS11-40-5922, taken from a position close to where Buzz stood for his iconic shot. The main thing to look for here is the large flat panel of the LM’s ascent module. Next to that we have AS11-40-5927, taken from a position east of the LM, looking towards that same flat panel. These two images are intended to set up the 3rd, AS11–40-5923 so that we can clearly see that it is taken a leg on the eastern side of the LM, looking westwards. This image from the TV broadcast shows where Aldrin was stood when he took it, and compares it with the LRO image we used earlier.

Buzz is very obviously at the base of the strut identified in the LRO view, as it is the next one around from where Buzz stood for his portrait. He is also looking in the right direction - west. He is also angling the camera upwards. Angling? What sort of angle? Well, here’s another 59 degree line positioned to run through the camera, which he has removed from the chest mounting (he hands to back to Neil shortly afterwards):

There we have it, roughly the same spot in the visor as the previous Earth image, although admittedly it is not of the same blue-white hue. Is it definitely Earth? I would suggest it is highly likely.

What about other missions?

Apollo 17’s relatively high latitude and half-Earth phase means that we have the opportunity for a couple more visor shots, specifically in a couple of photographs taken at the LM at the start of EVA-3. At the start of this EVA, both Jack Schmitt and Gene Cernan posed for photos by the lunar rover, and a couple of examples can be seen below in the shape of AS17-140-21386 and AS17-140-21391 shown below left and right respectively, together with a mirrored crop of their respective visors.

Clearly visible is the feature known as the South Massif - large enough to be seen with a decent amateur telescope from Earth. Above the centre of the Massif is a pale blue dot.

So far so good, but can we be sure it is Earth?

Well, we know what time the photographs were taken so we can plot in Stellarium and see where Earth should be, like this:

The key information here is that Earth should be at an angle of just over 240 degrees from North, and at an angle of just under 45 degrees from horizontal. We can draw on Google Earth here for some help to show that it is looking in the right direction.

In the image below there is a red line drawn from the landing site through the centre of the southern Massif at an angle of 240 degrees from North. The landing site is centred on the compass rise, The Google view is rotated 90 degrees so that it matches the Apollo views better.

Next to the Google Moon view is a rotated AS17-134-20473, taken at the end of EVA-3 looking towards the Massif and with Earth clearly in view.

What more needs to be given to show that the pale blue dot in the visor is the Earth?

We could try one more thing, just for fun. The ‘March to the Moon’ site has some high resolution scans of Apollo images, and one of them is AS17-140-21369. It is, as you can see below, a shot taken of Jack Schmitt at the rover. If you zoom into the highest resolution available here, you can tell that there is a reflection of the south massif.

I will be the first to state clearly that the image above right has been sharpened and adjusted considerably, but absolutely nothing has been added to the image. For my money, there is a blue-ish dot in the same place as the blue dots in the previous images.

To be equally fair and honest, there is no similar feature in the two preceding images, although these are arguably less sharp and show less visor.

Take your pick.

However debatable this final image is, the portrait photos of the two astronauts undoubtedly show Earth exactly where it should be in the lunar sky.

Another case of ‘blink and you’ll miss it comes from an Apollo 12 image, AS12-46-6729, seen below.

It’s back of the envelope stuff, and his camera isn’t pointing directly at Earth, but it looks pretty much bang on for where the Earth is. It’s always possible that this one is the photo of the LM base - he does move out of shot then and says to Neil that it is “too great an angle”, the subject being Earth. He is, however, definitely in the right place to take the Earth images.

There we have it, all done very simply and straightforwardly. Buzz’s visor image shows Earth, and it is Earth because the evidence all matches up with that.

The next question must be: are there any other examples of this? As it happens, there are.

AS11-40-5949 shows Aldrin deploying the seismometer. In the background is the LM, and we can see from its oritentation that the panel below which the photographs discussed above were taken is hidden from view. This means that Aldrin is looking towards where Earth would be in the sky, so with any luck it will be visible in his visor here as well. Below left is the original, while below right is one with a bit of brightness adjustment and sharpening from the highest resolution version available.

If you zoom in closely to the Alan Bean’s visor, you can see that there is a bright blob clearly visible. Is it Earth?

We know that Bean set foot on the lunar surface at 12:13 on 19/11/69, and here is what Stellarium says should have been visible at that time for Apollo 12’s location:

Earth is high in the sky, but it is in fact only a couple of degrees higher than it was in the case of Apollo 11, and it does appear in a similar (and slightly higher) place in the visor compared with Aldrin’s.

Can we reasonably conclude it is Earth? Maybe.

The Stellarium figures suggest only a couple of degrees of horizontal separation between the two, so a lot depends on the influence of the visor’s curvature. In Aldrin’s famous visor shot the Earth is almost directly in line with Armstrong’s shadow, whereas here it is off to one side of Conrad’s. However, when you look at the Apollo 11 example taken side on where I suggest Earth is present, it shows a similar displacement.

We also need to bear in mind that the Earth at that time was a relatively thin crescent. We do know from Apollo 14 images, however, that a thin crescent is still very bright, and it could be argued that it is proportionately less bright in Bean’s visor compared with the other visor shots examined here.

Could it be Earth? Possibly. Is it definitely Earth? It’s not certain, it could even be sunlight flaring off some part of the LM structure, but it’s worth putting out there.