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There is a large, diffuse, bright area in the otherwise black sky in some of the Apollo mission images from the moon's surface. It is not the sun. What can it be?

In the images below, I am comparing the original image with one I modified by bumping up the contrast and brightness to accentuate the bright areas.


Apollo 14, Feb. 1971. Astronaut Edgar D. Mitchell. What is the big bright area on the right side?

AS14-64-9089 (5-6 Feb. 1971) Astronaut Edgar D. Mitchell - Contrast 0, Brightness 0 AS14-64-9089 (5-6 Feb. 1971) Astronaut Edgar D. Mitchell - Contrast +60, Brightness +100
Source: AS14-64-9089 (5-6 Feb. 1971) Astronaut Edgar D. Mitchell - High Resolution Picture.
Left: Original AS24-64-9089. Right: Contrast +60, Brightness +100


Another similar picture, this time from Apollo 11, July 20, 1969, Buzz Aldrin descending the ladder of the Lunar Module (LM). What is the bright area in the upper left, in the sky?

AS11-40-5868 (July 20, 1969) ALDRIN DESCENDING LADDER - Contrast 0, Brightness 0 AS11-40-5868 (July 20, 1969) ALDRIN DESCENDING LADDER - Contrast +60, Brightness +100
Source: AS11-40-5868 (July 20, 1969) ALDRIN DESCENDING LADDER - High Resolution Picture.
Left: Original AS11-40-5868. Right: Contrast +60, Brightness +100


Same photo (July 20, 1969) from a different source.

AS11-40-5868 (July 20, 1969) ALDRIN DESCENDING LADDER - Contrast 0, Brightness 0 AS11-40-5868 (July 20, 1969) ALDRIN DESCENDING LADDER - Contrast +60, Brightness +100
Source: AS11-40-5868 (July 20, 1969) ALDRIN DESCENDING LADDER - High Resolution Picture.
Left: Original. Right: Contrast +60, Brightness +100

  • 3
    Got outside at night with a very strong light source such as a 3 million candlepower spotlight just outside the camera's field of view but able to shine on the front surface of the lens from off axis. Overexpose by about 5 stops and you'll get the same thing. There is lens flare in practically every photo. Normally it is muted enough to be made imperceptible by the other light falling on the sensor or film. But when the background is solid black there is nothing to mask the lens flare. – Michael C Aug 9 '16 at 0:31
  • I added another picture, AS11-40-5868 (July 20, 1969), which I have from two different sources. One version, once the contrast and brightness is modified, shows a big round light on the black sky, the other not. – Robert Werner Aug 9 '16 at 5:21
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    The second photo has clearly been cleaned up before being posted. What question do you still have here? – Philip Kendall Aug 9 '16 at 8:45
  • It's also an obviously darker version. Keep pushing the brightness and some of that haze/flare will become more pronounced. – Michael C Aug 9 '16 at 19:17
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It looks like lens flare. It is an internal reflection inside the lens. It is caused by off axis light allowed to fall on the front surface if the lens from outside the field of view.

For an example of such flare when the exposure is brightened please see: Can you photograph the milky way with a full moon out?

It might also be sunlight reflecting off dust that has been kicked up by the astronaut. In the moon's gravity field that is only 1/6 as strong as that of the Earth's the same amount of force would cause the dust to go 6x higher before falling back to the surface and it would also take 6x as long for such dust to settle as it would in a vacuum under Earth's gravity. There is also no atmosphere and thus no wind to disperse the dust.

It might be possible that dust could be electrostatically stuck to the front of the lens in some of the photos taken on the surface of the moon. In the case of the Apollo 11 photo of Buzz Aldrin descending the ladder of the LEM the absence of such a smudge in photos taken subsequently argues strongly against that theory. The Apollo 11 mission only included a single EVA, so all photos of Aldrin on the Moon's surface were necessarily taken after the photo of him coming down the ladder of the LEM.

This image was 34 frames later from the same film magazine on the same camera as the shot of Buzz descending the ladder:
enter image description here
Notice that there is no evidence of dust on the lens. If one examines all of the images from that magazine it quickly becomes apparent that the angle of the sun to the camera and whether the camera is in the shade of the LEM or not are the most determining factors regarding which images demonstrate the effect and which ones don't.

Likewise, if one examines all of the images in sequence from film magazine LL on the Apollo 14 mission it becomes abundantly clear that lens flare is the main culprit.

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Thank's to Makyen quote I am posting this option.

It could be some fine dust in the front of the lens.

Fine dust can stick to a surface by electrostatic charges.

Moondust was a real nuisance for Apollo astronauts," adds Abbas. "It stuck to everything – spacesuits, equipment, instruments." The sharp-edged grains scratched faceplates, clogged joints, blackened surfaces and made dials all but unreadable. "The troublesome clinginess had a lot to do with moondust's electrostatic charge."

http://science.nasa.gov/science-news/science-at-nasa/2008/10apr_moondustinthewind/

Now that I think more of it, the pattern does not resemble lens flare, because it is more irregular.

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There are thousands of pictures from the Apollo missions; it stands to reason that many of them exhibit the same sort of defects common to terrestrial photography. In this case, the problem is lens flare, which we can prove to a reasonable degree by comparing the sample images to similar ones where the artifact is more clear.

For example, in AS12-51-7587, from the Apollo 12 Command & Service Modules,

AS12-51-7587

NASA explains:

The brightness in the lower left corner of the photograph is a lens flare caused by sunlight reflecting on the window and the lens of the handheld Hasselblad camera.

See the light purplish pentagon to the right of the moon? That's the shape of the aperture of the lens.

Or, from the lunar surface AS11-40-5873, from Apollo 11,

AS11-40-5873

we again see very obvious lens flare including the pentagonal shape of the aperture. That shape isn't visible in your first example, but that's because it's right on top of the astronaut and thereby obscured. If we look at the next frame in the sequence*, it's more clear, as Mitchell has moved forward:

next frame

although it's not exactly perfect geometry, it's definitely apparent as lens flare — and if we look at the same shape with slightly different alignment just a few frames earlier, we see it even more clearly:

enter image description here

Here, the camera is turned so the flare nicely shows a ghost image of the pentagonal aperture, and one can pretty easily see that it's the same general structure as the flare in your first example.

So, overall, there's clear evidence that this is simply lens flare.

To avoid this, the astronauts could have waited until the lunar sky was more overcast, so the sunlight was less harsh. But I guess they were in a hurry. And a lens hood probably would have helped, but it was probably too much of a bother to run back for one.


* Thanks Michael Clark for the link to the gallery.

  • On the Moon you can not wait for the Sun to change its position on the sky because each day lasts two terrestrial weeks. Apollo 17 had resources for only ~72 hours. Regarding the overcast (en.wikipedia.org/wiki/Overcast) it seems that such a phenomenon does not exist on the Moon. – Robert Werner Aug 11 '16 at 20:26
  • @Robert Right; it's the camera that has changed position, not the sun. Notice the difference in the background. As for overcast, see the link I provided. I agree that it'd be a long wait. – mattdm Aug 11 '16 at 20:30

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