Apollo 8 - Outward

4.1 Apollo 8

Apollo 8 is of significance because the astronauts on board became the first people to see the far side of the moon, and the first to witness an Earthrise: the apparent rising of the Earth from below the Moon's horizon as the orbiting spacecraft reached Mare Smythii in its passage around the Moon. This phenomenon had, of course, already been witnessed by Soviet and US unmanned probes, but to be captured by human eyes added more significance to the event.

The mission was launched on 21/12/68, reached lunar orbit on 24/12/68, and re-entered the Earth's atmosphere on 27/12/68. During that mission, 865 images were taken on 7 film magazines. The majority of the images were used as source material for preparing future landing sites, but images of Earth are found on magazines 12-16. A number of TV broadcasts were also made, and images will also be examined from those broadcasts. Each image will be given in its original form, then compared with satellite images from the same day. The importance of the original image is mostly to demonstrate how small the Earth is in those images, despite their ability to reveal tremendous amounts of detail.

ESSA 7 images are available in this document: ESSA 7 data catalogue. I actually own a hard copy of this and confirm that the online scan is absolutely accurate. ATS-3 and ATS-1 images for at least some of the mission can be found in here ATS-III data catalogueThis document has ESSA-7 images covering the north Atlantic throughout the mission and these are added where possible. The full transcript of the mission can be found here: NASA link.  The mission timeline is here: NASA link. The final section will look at the meteorological data available, to see how the photographic record compares with ground based measurements of the weather at the time.

4.1.1a  Apollo 8 Still images – on the way to the Moon

The first magazine containing images of Earth is number 16. This magazine is notable because it contains images from all stages of the mission from initial low earth orbit, separation of the Saturn IV-B stage, lunar orbital images, and then images of the approaching Earth on the voyage home. It was also used in the TV series ‘UFO’ many times between 1969-70, and in the 1972 film ‘Silent Running’ as the film’s hero looks back to Earth through a telescope. The first image showing the entire Earth is AS08-16-2593 (figure 4.1.1), and it is compared with satellite images in figure 4.1.2.

Figure 4.1.1: AS08-16-2593 High resolution source

Figure 4.1.2: ESSA-7 satellite images compared with AS08-16-2593 and Stellarium estimate of time at terminator.

It is also taken very soon after separation from the Saturn IV-B rocket, as there are photographs of this event before it in the magazine. According to the timeline this occurred at 16:12 on 21/12/68. The most obvious features include the large spiral cloud system in the North Atlantic (yellow arrow), the '<' shaped cloud feature off Brazil (green and magenta arrows), and lines of clouds trending south-east from Argentina (blue and cyan arrows).

It is also worth noting the shadow under the linear cloud mass near the terminator over north Africa (picked out by the green arrow). The direction of that shadow under the clouds is consistent with the sun's direction at sunset.

Stellarium (an astronomical software package used to identify the location of celestial bodies: http://stellarium.org) can be programmed with times and locations. In this case, using the lunar surface as a view and changing the date to the 21st gives a time for the Apollo image of around 17:15, shortly after the initial separation from the SIV-B rocket stage and the trans-lunar injection (TLI) engine burn. It's also worth noting the difference in perspective of the observer. Stellarium's Moon based view is looking 'up' with the southern Hemisphere dominating the view. Apollo's vantage point shows more of the northern hemisphere. At the time the image was taken, the transcript records a crew comment saying that:

"..it's a beautiful view with numerous cloud vortex..I can still see the Cape and isthmus of central America"

ESSA 7 data suggest that South America would have been photographed by the satellite at about 19:09, as this was when track 3 (pass number 1594) of the satellite's daily orbit over it was commenced. The time over the terminator area would be more covered by track number 1, orbit 1592, which commenced at 15:05. At the time of the Apollo image, then, it would be another 2 hours before the satellite would image the area photographed, and there would be a further few hours on top of that before all the visible Earth was covered.

The next in the series of images taken showing any significant change in the scene below them is AS08-16-2595, which is shown below in figure 4.1.3, and analysed in figure 4.1.4.

Figure 4.1.3: AS08-16-2595 High quality version here: AFJ

Figure 4.1.4: ESSA-7 satellite image compared with AS08-16-2595 and Stellarium estimate of time at terminator.

In this image, the long shadows are cast by the clouds over the Amazon, and the yellow & purple arrows point to the same weather systems as they do in the previous figure, although only the thin tail curling away from the yellow arrow system is still visible.

Much more prominent now are a large spiral system off the north American coast and below Alaska (green arrow), and the scattered clouds over the south Pacific. There is also a prominent plume of cloud heading northwards from Antarctica (magenta arrow), and a small whirl of cloud off south America (red arrow) that are all easily found on the satellite image, along with all the other weather patterns.

The Earth has rotated by a consistent amount between the first two photographs analysed, the shadows lengthen at the terminator, and the weather systems are still visible from the previous image. The bright spot showing the sun's reflection can be seen in this image, and the perspective of the photographer has changed noticeably, with much more of the Antarctic region in view.

Stellarium suggests a terminator time of around 20:45 on the 21st.  The ESSA track over the terminator region was commenced at 17:00, as this was when track 2 (pass number 1593) began, as discussed for AS08-16-2593.

AS08-16-2596 shows a very similar view but is rotated slightly, and there isn’t enough difference to make it worth a separate treatment. The next frame in the magazine we have another view of a still more rotated Earth, and this time it has moved far enough to allow an image from ATS-1 to be included in the analysis. AS08-16-2597 is shown below in figure 4.1.5, and compared with the satellite images in figure 4.1.6.

Figure 4.1.5: AS08-16-2597. High quality source:  AFJ 

Figure 4.1.6: ESSA 7 (left) and ATS-1 (right) images compared with AS08-16-2597 and Stellarium estimate of time at terminator.

Although there is no land visible in the image, it is possible to mark the position of the terminator with Stellarium by using the previous image analysis as a reference. The weather system highlighted by the green arrow is the same in figure 1.1.6 as in figure 4.1.4, which means that the terminator is just about on the west coast of the USA, which puts the time at around midnight on the 22nd. This corresponds well with the ATS-1 image, which was recorded at 00:54 on the 22nd, and it is evident from it that the eastern half of the image is in, or close to, darkness.

Stellarium also indicates that Australia should be visible on the western limb. This part of the Apollo image is a little washed out, but the magenta arrow points to a band of cloud that should lie off Australia's east coast and that is visible in all 3 images presented here.

The presence of that green-arrowed system is another clue, if one were needed, that this is a picture that is part of a continuous sequence recording the Earth as it rotates, and not some sort of made-up on the spot fiction. As with the other images, and as will become apparent for every other image presented throughout the entirety of this report, the cloud systems on the satellite images match those of the Apollo image. The ESSA path that most represents the terminator line is track number 5, which corresponds to orbit number 1596, which commenced at 22:05 on the 21st.

No specific mention of the actual time of  the photograph, but the transcript does have the crew querying what settings they should be using on the camera, and stating at around 01:00 that:

“This PTC attitude isn't the greatest for taking pictures of the Earth”

PTC stands for 'Passive Thermal Control', or the 'barbecue roll' slow rotation that allowed the CSM to balance its temperature in direct sunlight.

A few hours later, we have the next image of Earth showing movement, AS08-16-2599. This is shown below in figure 4.1.7, and analysed in figure 4.1.8.

Figure 4.1.7: AS08-16-2599. High quality source:  AFJ

Figure 4.1.8: ESSA-7 image compared with AS08-16-2599 and Stellarium estimate of time at terminator.

The rotation of the Earth in this photograph compared with the previous one is such that the ATS image no longer has any features that are visible in it, and the only weather system identified in the previous image that is also identifiable in this one is the one picked out by the magenta arrow.

The system picked out by the blue arrow in figure 4.1.6 can still be seen on the satellite image, just as the green arrow here identifies a weather pattern that was visible on the ESSA part of figure 4.1.6, so it is obviously a continuation of the weather observations on the day. The plume of cloud extending up from Antarctica (yellow) is very easy to pick out in the Apollo image, as are the streams of west trending clouds to the west of it (purple and cyan arrows), the 'Y' shaped pattern near the equator (red arrow), and the Himalayan clouds (blue arrow).

Stellarium shows that the terminator is showing a time of approximately 07:00, and this can be compared with an ESSA time for the orbit nearest the terminator of 02:05 (orbit 1598, track 7).A couple of images later in the magazine we have another new image of Earth, this time showing Africa as the dominant land mass in view. AS08-16-2601 is shown below in figure 4.1.9, and analysed overleaf in figure 4.1.10.

The ESSA-7 image in that analysis is dated the 22nd, and the dividing line between those orbits that started on the 22nd and finished on the 23rd can be seen to the east of Africa in the southern hemisphere, running up Arabia and across eastern Europe in the northern hemisphere., The majority of the Apollo image is west of that line.

Figure 4.1.11: AS08-16-2602 High quality source:  AFJ

Figure 4.1.12: ESSA-7 (left and above) and ATS-3 (right) images compared with AS08-16-2602 and Stellarium estimate of time at terminator.

The green and purple arrows in figure 4.1.12 point to the same systems shown in figure 4.1.10, and the thin swirls of cloud discussed previously are now clearly in view (red arrow). Similar thin wispy bands of cloud can be seen off the coast of south America (south of the cyan arrow).

For the first time in this section, an ATS-3 image is usable, and this is also showing an excellent match to the Apollo picture. That image was taken at 14:58, and it is evident that the terminator is much further east in that image compared with Apollo's.

ESSA's orbit best matching the terminator is number 1606 (track 2) which commenced at 18:05, just 55 minutes before the Apollo photograph, which Stellarium puts at 19:00.

Ostensibly, the ATS & Apollo images seem (terminator line apart) identical, but there are subtle differences. The clouds over the always dynamic Amazon climate system, for example, are in a different formation to Apollo's, where they are much more similar to the ESSA image taken nearer the time. There are also differences in the way the twin streams of cloud picked out in red are shaped. In ATS-3, they are much more definitely joined to the main bank of cloud (green arrow) and diverge more as they move westward. In the ESSA image, as with Apollo, the northernmost stream has broken away from the main bank of cloud, but there is a wider gap between the streams and they appear more parallel. This is a common theme throughout this research: ostensibly identical systems in fact showing small variations that are entirely consistent with the time differences between the images concerned.

A short while after AS08-16-2602, we have AS08-16-2604. This photograph shows a very similar scene to that of 2602, but much of northern south America has passed beyond the terminator, and more of the Pacific is in view. AS08-16-2604 is shown in figure 4.1.13, and analysed in figure 4.1.14.

Figure 4.1.13: AS08-16-2604. High quality source:  AFJ

Figure 4.1.14: ESSA-7 (left) and ATS-3 (right) images compared with AS08-16-2604 and Stellarium estimate of time at terminator.

As suggested previously, little has changed in the weather systems already shown, but it does serve to show (again) that the Earth is rotating as the CSM gets further away, and that that rotation brings into view weather systems that were previously hidden. There is no change in the ATS-3 timing, but ESSA's most representative track for the terminator region is number three (orbit 1607), one orbit later than the preceding image, and therefore starting at 20:00.

Stellarium suggests a time for the image of 21:30, just 90 minutes after the previous one, and all of the colours for arrows to identify weather systems in figure 4.1.12 apart from the green and red ones are used again. The reader is also referred back to figure 4.1.4, which showed the same view roughly 24 hours earlier, and where magenta is used to identify the same weather pattern. Those two day's weather patterns are compared below in figure 4.1.15.

Figure 4.1.15: AS08-16-2595 (right) compared with AS08-16-2604 (left)

The two days’ images show what is obviously the same weather system, but that has developed over 24 hours to extend further northwards, while a frontal band to the west moves further eastwards towards Chile.

Next up in the sequence of images is AS08-16-2605, and as will be seen shortly shows a relatively small amount of rotation since the preceding photograph on the magazine. Figure 4.1.16 shows the original Apollo image, and 4.1.17 the analysis. The degree of movement is enough to mean that there is a small amount of surface covered by both ATS-1 and ATS-3.

Figure 4.1.18: AS08-16-2606. High quality source:  AFJ

Figure 4.1.19: ESSA-7 (left) and ATS-1 (right) compared with AS08-16-2606 and Stellarium estimate of time at terminator.

The Earth has rotated sufficiently to lose the ATS-3 satellite, and the ATS-1 dated the 23rd is now nearer in time than the 22nd. ESSA's image date is still the 22nd.

The ATS image was actually taken at 22:43 on the 23rd, over 20 hours after the Stellarium estimate of the image time, and understandably there is a much bigger difference between the Apollo image and ATS-1. However there are, as can be seen from the arrows used, still identifiable weather systems that can be seen on both those images.

Of those systems, the most striking ones are at the northern and southern ends of the planet. In the north there are the two frontal bands (green and red arrows) marking the boundaries of lighter swirls of cloud between them. To the south there are the storms heading north from the Antarctic, including the striking tight curl of cloud marked by the yellow arrow, and the long band of cloud making its way to Australia's east coast.

ESSA is a much better match for the Apollo image, and this is explained by the images being taken much closer in time to it. Orbit number 1609 (track 5) is the closest to the terminator, and commenced at 23:00 on the 22nd.

The next image in the magazine (AS08-16-2607) has rotated slightly from the one used above, but there isn’t enough of a difference to make it worth examining as a separate case. Therefore the next photograph from magazine 16 to be analysed is one of the final pair from it before images of the lunar surface are found, which at the very latest puts it at before the 25th of December, and once again south America is the dominant view in the photograph. AS08-16-2608 is shown below in figure 4.1.20, and analysed in figure 4.1.21.

Figure 4.1.20: AS08-16-2608. High quality source:  AFJ

Figure 4.1.21: ESSA-7 (left and above) and ATS-3 (right) compared with AS08-16-2608 and Stellarium estimate of time at terminator.

While the Christmas day 1968 is the very latest that the picture could have been taken, the satellite record places the photo graph very definitely on the 23rd, with Stellarium placing the time at 21:00 on that date. ATS-3's image was taken at 18:16 on the 23rd, while the area around the terminator line was imaged by ESSA on orbit 1618 (track 2), which commenced at 17:05.

At 55 hours of mission elapsed time (MET), or about 19:55 on the 23rd, the crew gives confirmation of what is in the photograph by describing the view as seen through the TV cameras in their second transmission to Earth:

"..what you are seeing is the western hemisphere...I can see Baja California and the south-western part of the United States. There is a big long cloud bank going north-east covers a lot of the Gulf of Mexico, and it appears now that the east coast is cloudy. I can see clouds over parts of Mexico, the parts of central America are clear...a long band of - it appears cirrus clouds that extend from the entrance of  the Gulf of Mexico going straight out across the Atlantic Ocean right now going from north to south. Southern Hemisphere is almost completely clouded over, and up near the North Pole there is quite a few clouds. South-western Texas and south-western United States is clear. I'd say there are some clouds up in the north-west and over in the north-east portion."

Looking at the Apollo photograph, they are describing accurately what they can see, and have not (as in all cases when discussing the view of Earth on any mission) been prompted in any way. The long cloud heading north-east from the Gulf is indicated by the blue arrow, and the thin cirrus clouds described from the Gulf into the Atlantic are likely to be the ones pointed out by the red arrow (although they actually extend from north to south only if coming from the Atlantic). The maroon arrow points to the same weather system off the coast of Chile identified in previous images, and the purple and yellow ones over south America itself also point to weather systems identified on the previous day by the same colours in figure 4.1.14.

The next images from Apollo 8 are from lunar orbit. Click the buttons below to navigate there or elsewhere.

Figure 4.1.9: AS08-16-2601. High quality source:  AFJ

Figure 4.1.10: ESSA-7 images compared with AS08-16-2601 and Stellarium estimate of time at terminator.

As usual, the weather patterns on the satellite images correspond exactly with those on the Apollo image, and several of the cloud systems visible in this image will be seen in later ones, not least the spectacular 'dog-leg' frontal mass connecting the Antarctic to south America (purple arrow), and the large frontal mass preceding a series of thin lines of cloud in the north Atlantic (green arrow, although only the main cloud front is visible in this image).

Although the Apollo image is slightly out of focus, it is still possible to pick out the thin clouds over north Africa (eg the cyan arrow), the coastal cloud banks around southern Africa, the typical frontal system off South Africa itself (yellow arrow).

The astronauts themselves describe the view to the ground at exactly the same time as this image was taken:

"This is a mighty nice view we have down there today, A little bit more than a half Earth. Looks like Africa and the Red Sea is visible we're not quite sure as there is quite a bit of cloud cover."

Stellarium suggests a time of around 14:00 on the 22nd for this image. ESSA's nearest track to the terminator is track 11. This is orbit number 1602, which is labelled as the first orbital pass on the image dated the 22nd, and was commenced at 10:05 on the 22nd. The ESSA satellite would barely cover the area around the terminator before the Apollo image was taken, never mind the rest of the photograph.

The next image in the magazine, AS08-16-2602, shows that another few hours have elapsed, and south America dominates the scene. This photograph is shown below in figure 4.1.11, and analysed in figure 4.1.12.

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Figure 4.1.16: AS08-16-2605. High quality Source: AFJ

Figure 4.1.17: AS08-16-2605 compared with ESSA (top & bottom left) ATS-1 (top right) and ATS-3 (bottom right) images dated 22/12/68, with Stellarium estimate of time at terminator.

We’ve now moved on a couple of hours, and the Rocky mountains are beginning to disappear into night. There is no direct reference to the photograph being taken, but roughly an hour later communications issues led to Hawaii being asked to send messages, suggesting that the Pacific view in the photograph is consistent (as we would expect) with the mission narrative.

The area shown is an intermediate one between the those covered by ATS-1 & 3, but the blue arrow points to the same system as is shown in figure 4.1.14. The most distinctive weather system is that off the Californian cast, where two bands of clouds separate and then rejoin in a long arc (red and green arrows).

As the time suggested by Stellarium is 23:30. The ATS-1 image was taken at 00:54 on the 22nd, so is some time before the Apollo image, but as the next ATS-1 image was taken at 22:43 on the 23rd, it falls almost exactly between the two. This time gap is enough to explain the small-scale differences, but is close enough temporally to cover the large scale similarities.

ATS-3 was taken much closer, 14:59 on the 22nd. While not identified specifically, there is good correspondence between the Apollo photograph and ATS-3 in terms of the swirl of light banded cloud off western south America.

ESSA’s image is a much better match than either of the ATS satellites, as its orbital pass is much closer in time.  The closest pass to the terminator is number 4, or pass 1608, which started at 21:05.

The next image of Earth is AS08-16-2606, shown below in figure 4.1.18, and analysed in figure 4.1.19, and is taken not long after the preceding one.