Starship Asterisk*

Ron-Astro Pharmacist wrote: This may seem a stupid question but it’s never stopped me before – How many of the rocks in the picture are moon rocks vs. debris left over from the meteor that hit the moon?

Could we get a good sampling from the material brought back by our Apollo astronauts to know how much of the soil/rock were lunar in origin in the vicinity of an impact crater like this?

I might think that most of the rocks are lunar but most of the soil from micro-meteoroid origin.

Sinan İpek wrote:I think those cameras used by Apollo were calibrated finely, i.e. their white balance. And also, the film emulsion used by NASA is kind of superior to those brand new electronic CCD's used by Chineese in maintaining colors.

Chris Peterson wrote:

Sinan İpek wrote:Why in this photo does the moon soil seem greenish (or brownish) while in Apollo photos it is mostly gray?

I wouldn't describe the color as greenish, but it's always dangerous to look too closely at the color in images- and not just astronomical images. Just pick any well photographed object on Earth and Google some images. The color will be all over the place. Accurate color (to the extent such a thing even exists) depends on very complex calibration, and even then, two different instruments will never produce identical results. It's hardly surprising that the we see some difference between a modern electronic sensor and 1960s era film emulsion.

Chris Peterson wrote:

Ron-Astro Pharmacist wrote:This may seem a stupid question but it’s never stopped me before – How many of the rocks in the picture are moon rocks vs. debris left over from the meteor that hit the moon?

While it's technically possible for a body to strike the Moon as slow as about 2 km/s, that would be incredibly rare. The typical range of speeds is much higher, with an average of around 40 km/s. What that means is there are virtually no meteorites on the Moon. Without an atmosphere to slow meteoroids down, they vaporize on impact. So if you look at the lunar regolith, you'll find microscopic dust of extralunar origin. But by far most of the dust is lunar in origin, as are all the rocks large enough to see.

I found the answers given to be really informative.

Sinan İpek wrote:Why in this photo does the moon soil seem greenish (or brownish) while in Apollo photos it is mostly gray?

Ron-Astro Pharmacist wrote:This may seem a stupid question but it’s never stopped me before – How many of the rocks in the picture are moon rocks vs. debris left over from the meteor that hit the moon?

Wikipedia wrote:Over time, material is mixed both vertically and horizontally (a process known as "gardening") by impact processes. However, the contribution of material from great distances is relatively minor, such that the soil composition at any given location largely reflects the local bedrock composition.

rstevenson wrote:

Sinan İpek wrote:Why in this photo does the moon soil seem greenish (or brownish) while in Apollo photos it is mostly gray?

The colour photos from the Apollo landings show lots of colour in the soil. Here's a section of an Apollo 14 panorama near the Mauro Highlands, compared to the soil around Yutu.

Apollo 14 - soil.jpg

Yutu - soil.jpg

You can likely see some colour variation in the Yutu image -- two vertical purple streaks in particular. This is repeated over and over again across the panorama, suggesting to me some sort of refraction issue in the lens. For this and other reasons I wouldn't attach too much weight to the exact soil colours as shown in these released images.

Rob

Sinan İpek wrote:Why in this photo does the moon soil seem greenish (or brownish) while in Apollo photos it is mostly gray?