Short Wavelength compositional analysis with UV / IR filters with the Orion 10" f/3.9 Newtonian Astrograph June 13, 2016 Uploaded 7/21/16

 Although color variations on the moon are so subtle as to be nearly invisible to the naked eye, we can differentiate rock and lava colors with CCD cameras with suitable filters.  Materials that are brighter in the shorter - hence bluer wavelengths are higher in metals in their composition, and more silicate based rocks are brighter in longer - thus redder wavelengths.  For this experiment, I used an Orion UV and IR pass filters to differentiate the rock types.  By imaging the lunar surface with all reflective optics  to ensure sharp focus at both wavelengths - and looking at the difference between the images by subtraction,  I can enhance the more UV reflective materials and identify the areas on the moon that are more metal rich, or have had a more recent impact which are bluer - and stand out over the more weathered darker rock on the surface.

The results of this differentiation were surprising!  It is widely known that Mare Tranquillitatis is rich in blues from metals like titanium in the lavas, however other areas have peculiar shadings that do not seem to have any visible light equivalent structures.  Here are some of the results in review from this exercise.

Note: Conventional usage of South is up in all images, more info below.
Raw Infra Red image at prime focus with the 10". Note that the "lake" inside Mare Serenitatis is easily visible.
Raw Ultra Violet image - the "lake" is now invisible at short wavelengths.
Here is the full field (quarter of a degree), I can get about a quarter of the of the full disk of the moon with the 10 inch with its 1000mm FL. The upper image is a conventional white light shot, and the lower is UV-IR to accentuate bluer regions as white, the equally reflective areas are grays, and the blacks are the areas that reflect more of the longer redder wavelengths. Many of the craters are completely gone! However, quite a few bright spots that remain are fresher craters that have UV bright ejecta or have exposed new material from underneath. We will now zoom in on various sectors of this high resolution image and take a closer look. Select size for enlarged view: 1400 x 1200
I find this to be one of the most amazing images in the set! Ive highlighted in each image some areas of interest. Lets take a look at each one in turn. Again, Im merely showing the color contrasts between UV and IR here, the interpretation of the significance of such color variations is beyond the scope of this write up.

A. The comparison between the ejecta patterns of Autolycus and Aristillus are interesting. while the upper crater - Autolycus is essentially sitting in a dark sea of redder material, Aristillus has an impressive apron of high UV reflective spray around it.

B. Archimedes is essentially featureless with a dark interior, however two banks of materials that are UV reflective are on the north and south sides just outside the crater.

C. Timocharis crater - locally bright ejecta very near the crater walls. Compare to Lambert (F).

D. The most fascinating area of all here, the sharp edged zones in the UV/IR reflectivity seem to show the boundaries of lava flows. But why do the edges of the zones become more intense in difference between UV/IR?

E. Really wild differences here! Leverrier is the crater on the right side of this zone, note the sharp boundaries with dark edges seen here marking the edges of layered lava flows.

F. Lambert Crater - sits in a zone of dark silicate lava. Just north (below) several zones in the lava fields are seen.

These two zones mark a very complex region around Mare Fecunditatis on the left and Mare Nectaris on the right. Well cover Mare Tranquillitatis in another panel.

The left most zone is an isolated area of enhanced UV reflectivity in Mare Feconditatis. Just above it to the south the rest of the sea is dark and more reflective in IR. The right side of the sea is a mix of both types.

But look the central zone! Messier A&B sit in a lighter zone of enhanced UV, but the rays that point to the right - the dual ejecta from their impacts is jet black. This shows that material from perhaps deep down had been scattered by the impact over the UV brighter lava flows on top.

Finally, the third right most zone is the sea Mare Nectaris. Look at the beautiful fan of UV bright material spraying up wards from the crater Madler. To its right is the ring of high sun lit crater Theophilus. A complex mix of light and dark material here.

The most intense region on the moon of high UV reflectivity is Mare Tranquillitatis. This entire sea is very bright in the UV and contains few zones of darker redder material.

A. The northern end of Mare Fecunditatis is uniformly bright in UV, covered in previous panel.

B. Messier A&B - The ejecta from this set of craters is black against a bright UV background!

C. Centered on the very peculiar crater Dionysius, the only crater on the nearside with black ejecta rays- has a significant area of UV brilliant ejecta.

D. The area of the moon with the brightest UV reflectivity is Mare Tranqullitatis. This must be a geologists and perhaps ore miners dream, so much metal rich lava has been found here, highlighted by some bright areas that are very extensive.

Another very complex region,


A. Mare Tranquillitatis, covered in previous panel.

B. Lalande crater has a large amount of UV reflective ejecta.

C. Copernicus ejecta spray apron. The rays of this great crater are very bright in UV, and considering that the crater itself is bright inside, this makes sense.

D. Copernicus crater. Look at this dichotomy in UV reflectivity! the lower right quarter of this crater is like a dark pie wedge shape of low reflectivity. What would cause this? A mystery!

Mare Serentitatis. The entire inner basin is lighter in UV than the edges. Many observers have indeed reported a ruddy color to the basalts here, very much like what I have seen on Mauna Kea in Hawaii.

A. Bright patch on shore of the sea near Litrow B crater.

B. Menelaus crater is VERY bright in UV and would seem to indicate its recent excavation.

C. Bessel crater, in the mid section of Serenitatis, with bright ejecta wrap.

D. Just below Bessel is this odd cone shaped zone of high UV reflectivity.

E. The range of mountains on the north end of Serenitatis shows a contrasting brighter more gray colored area but just to its south is a dark UV absorbing zone.

F. Aristillus crater with a fantastic UV bright ejecta pattern!

Color mapped full image showing bright zones are more blue/UV reflective Select size for enlarged view: 1400 x 1200
Processing: 25/1200 best frames, alignment in Autostakkert, USM, Levels and Contrast Masking In Photoshop CS2 and Image J.
Instrument: Orion (GSO) 10" f/3.9 Platform: Astrophysics AP1200 CCD Camera: Image Source DMK 51 Filter: Orion IR Pass/UV Exposure: 1/30 sec 12fps Location: Payson, Arizona Elevation: 5150 ft. Sky: Seeing 2/5, Transparency 7/10 Outside Temperature: 75F