NOT the Moon

I've just spent a pleasant afternoon processing images taken last night of the comet C/2019 Y4 ATLAS. This was fun and educational. The sky was definitely not perfect for photographing the comet, since the comet was behind quite a lot of high cloudiness. My original thought was to get an LRGB (color) image, then see if I could get a time lapse showing it's movement across the sky. Well, it almost worked out that way. As I was imaging the different colors, the movement of the comet was faster than I thought it would be. From start to finish of the LRGB run, there was enough movement that the comet head could not align in the three colors. The result was a mostly color correct image, with the red channel showing thru separately at one point, just behind the head. It's clearly visible.

Comet C/2019 Y4. Yes, it really is green. (It isn't easy being green.... or so I hear.)

The second task was achieved by taking all of the channels separately and processing them into the “movie”, which is actually an MP4 file. If it's uploadable, I'll put it up here. If not, well, sorry. It's really pretty cool. It moved about 150,000 miles closer to the sun during the almost 1.5 hours of the imaging session.

Dorsum Burnet and the Head of the Cobra

Both of which are located in the image below. This is the continuing saga of processing the images taken the evening of March 7^th.

The general area is of the western edge of the moon, in Oceanus Procellarum, the Sea of Storms. Again, this is slightly “higher” up the terminator, but also slightly east, or right. The circled area contains the Dorsum Burnet. A “dorsum” is a lunar wrinkle ridge (dorsum is just the Latin name for ridge). A wrinkle ridge is a low, sinuous ridge on the moon. They are tectonic features formed when lava cooled and contracted. They are found in the mare and some crater floors. They often follow features, especially circular one, under the mare. The naming of the dorsa is apparently a somewhat hodge-podge affair. But this particular one seems to be fairly well identifiable. There are also many other dorsa visible, but not named, on the moon. This one was named for the 17^th century English naturalist Thomas Burnet.

The white arrow points to the “Head of the Cobra”, which is the southern end of Vallis Schroteri. Schroter's Valley is considered the longest sinuous rille or valley. I suppose the sinuous descriptor means that others can be longer if they are not sinuous. The “Head” is a crater. At the point of the arrow is a small rille on the floor of this valley which is the location of several transient lunar phenomena. From Wikipedia, a transient lunar phenomena is a short-lived light, color, or change in appearance of the surface of the moon. The assumption is that the TLP is outgassing or possibly impact cratering, although, if this seems to be a common location, I would guess outgassing. The very light crater the arrow is over is Aristarchus.

More on the Moon Take 2 … and more to come, probably

Continuing image processing from the 7^th, the following image is from further “up” the terminator.

Reiner Gamma and Kepler

I've marked 2 areas that I think are interesting. First, the crater Kepler, pointed to with the arrow. It's about 31 miles in diameter. I find the rays, ejecta actually, to be the interesting aspect. The ones to the left are quite long, reaching almost to the 2^nd area of interest, Reiner Gamma, the circled area. I wonder if the sparsity of ejecta on the right side of the crater means that the object that hit the moon there was traveling from right to left, more or less. I also wonder what caused the “jaggedness” of the rays. I would think they would be straighter. Is it just an illusion caused by the terrain?

Renier Gamma is something that has puzzled astronomers for 50 years or so, apparently. First identified as a crater by Francesco Maria Grimaldi and named Galilaeus by Giovanni Riccioli. IF, and that's another big if, I'm reading Virtual Moon Atlas correctly, the name Reiner Gamma was not adopted until 1935. However, what it is remains a mystery. It's called a lunar swirl, which I think is meant to be more of a descriptive name than anything else. It has the interesting characteristic of having a very strong localized magnetic field, as shown in this overlay map from the Quickmap reference below. The red area is around Reiner Gamma, the red indicating the strong magnetic field.

Magnetic field around Reiner Gamma

One of the theories of why it looks like it does, meaning lighter in”color”, is that the magnet field has not allowed the weathering of the solar wind that has occurred around it, darkening the surrounding area. All in all, this has been one of the more interesting rabbits I've chased in a long time. The moon is still an interesting place to study.

More on the Moon

Continuing image processing from the 7^th, the following image is from further “up” the terminator.

Rima Sirsalis

This is an annotated image from near the crater Sirsalis. However, the large dark-ish area on the right side is Mare Humorum (Sea of Moisture), with the crater Cassendi in about the 11 o'clock position on the rim of the Mare. But the star of the image is what is both circled and pointed to, Rimae Sirsalis. Rimae Sirsalis is, both apparently and in several references, the longest rille on the moon, about 460 km or about 265 miles. So, what's up with rima and rilles? “Rima” is the Latin term for rille. A rille is a fissure or long, narrow channel on the moon. Another interesting point I found while looking this up (while in “social isolation” for the COVID-19 virus pandemic); sources give different lengths for the rille (Virtual Moon gives it at 182 miles, WiKipedia is the source for 426 km). It would seem there is a problem that really shouldn't be a problem. My own estimation is around 217 miles, but I'm looking at it from an angle and at relatively low resolution. I suppose my guess is no better than the other 2, and perhaps no worse!

A Curious Sight on the Moon

The evening of March 7^th, the last evening with no clouds, I imaged portions of the moon. As usual for me, I “ran the terminator”, meaning imaging along the day/night line. Plus a little extra this time. Needing something to do while the skies are so cloudy , I'm still processing the images. The first one processed, however, has something I don't remember seeing, so I'm trying to find out more about it. It's one of those things that's certainly nothing, but I'm just curious. I'm also asking members of the Atlanta Astronomy Club to look at the images to see if anyone recognizes it. First, the processed image.

  

Original processed image, but substantially downsized.

And now, the curious feature marked.

Feature is slanted lines inside circle. Ray from Tycho is vertical line.

The “feature”, for lack of a better word, seems to be a series of light lines at an angle to one of the rays of ejecta from the crater Tycho. In tracking this down, I've been to the lunar quickmap

https://quickmap.lroc.asu.edu

to see if any of the layers might shed some light on the feature, but nothing seems to have helped. I feel fairly confident that it is not a surface feature like a crater rim or wrinkle ridge, so I'm thinking it might be ejecta from another crater, maybe??? Who knows? Maybe somebody. IF, and that's a big if, it is ejecta, which crater did it come from?