My new blog is up and ready to go…. I just need to get it linked to “Neish & friends”!
*update* It’s been linked! https://planetneish.com/research.html
My new blog is up and ready to go…. I just need to get it linked to “Neish & friends”!
*update* It’s been linked! https://planetneish.com/research.html
Today, much of North America got to enjoy a rather nice-looking Solar Eclipse. Me included!
Viewing an eclipse in progress is best done using a telescope decked-out for the job. For example, at Western U such telescopes were available for public use during a special event geared to this eclipse — here’s what the eclipse looks like through one such telescope (we got 75% at “maximum” here in London, ON):
But, what if you have no such luck and would still like to catch a glimpse of the event? Here are some cool tricks virtually anyone can take advantage of the next time they find themselves in the right place and time for a Solar Eclipse:
Using your phone’s camera:
It’s a bit tricky, but one can achieve some fairly good results when done properly. Basically, you use your phone’s camera to take an “indirect picture” of the eclipse. If you point your phone’s camera directly at the sun (this is the tricky part, because you need to angle your phone without also looking upwards lest you accidentally look directly at the sun), at the proper angle you should see a disk-like “reflection” in your image hovering near the sun itself. Depending on how far along the eclipse is, the reflection should appear as if it has a “bite” taken out of it; this is the eclipse! Here’s an example of what I’m talking about here:
The hand-made “pinhole camera” method:
Using your hand, make an “almost-fist” with it such that the sun’s light can still pass through the gap in your fist and onto the ground below. During the eclipse, it should appear as if a crescent-shape of light is cast onto the ground behind your fist. Below is an example (this method’s comparatively less tricky, since you don’t need to avoid looking up in order to ensure a good result):
If you happen to own a telescope of some kind…:
If you own a telescope, but not the resources/know-how to set it up for an eclipse then fear not! Your as-is telescope is still sufficient so long as you also own a square of cardboard. Using the cardboard, orient your telescope towards the sun (again, don’t use your own eyes!); once properly oriented, the disk should show up on the cardboard — hopefully being occluded by the Moon! If your telescope has a pinhole lens attachment, installing that to your telescope should make the resulting image clearer.
MDIS-NAC images have been downloaded for all the craters in my catalog that have useful NAC files worth downloading — all except two, if I remember correctly.
But, over half of my craters are already fit enough to be analyzed for melt and rim-low locations and so that is what I attempted to do this past week or so. Below is the gist of what I’m doing here:
Using the grid-like object, superimposed over the original GIS file, I mark out where the highest concentration of melt (in purple) is as well as the most likely location of the rim-low (in red). In the case of Balanchine crater, above, the location of this melt pool is in the W-WNW wedge, while the rim-low can be found within the NW-NNW wedge; this means that the melt is predominantly located within 45* of the rim crest low.
A number of craters need the MDIS-NAC for better locating the melts (and in a couple cases the crater floor), so that will be my next task at-hand. Then, I can add grids to those craters as well and fix up any hiccups that the already-completed craters had during this first run of mine through this process.
For me and my supervisor….
What I’ve done so far:
>>GIS files for most of my 36 craters have been created, with rim, floor, and melts shapefiles made for each.
>>MDIS-NAC files have been downloaded for all named craters (around 19 craters).
What I want to complete by September:
>>Download MDIS-NAC imagery for my unnamed craters and render all MDIS-NAC files in GIS to aid in completing the handful of crater GIS files that remain incomplete. [1 week + 1 week, max]
>>Complete all rim, floor, and melts shapefiles for remaining craters. [1 week, max]
>>Acquire MDIS-derived DTM map(s) from Preusker et al. (2011/2017/2017) for any outlying craters that still exist — if time permits, perhaps even add some southern hemisphere craters to my “catalog.” [1 week, max; 1-2 weeks for S.H. craters]
>>Conduct a statistical analysis on these craters, locating where the majority of melt emplacement is w.r.t. each crater’s rim crest low and then compare my results to the Neish et al. (2017) results. [1-2 weeks, max]
>>Analyze all the rayed craters in my “catalog” for evidence of impactor direction, perhaps using MESSENGER’s false-colour mosaic. [1 week, max]
>>Hope to begin to write-up my thesis come September (the above should take 6-8 weeks to complete, assuming no hiccups or what-not along the way).
I hope to have completed the first “to-do” objective by the time I draft my next blog post here.
The “Group of Seven” was the name given to a number of Canadian artists who painted landscapes in the same style at around the same time; the original group was: Franklin Carmichael, Lawren Harris, A. Y. Jackson, Frank Johnston, Arthur Lismer, J. E. H. MacDonald, and Frederick Varley. Tom Thomson was noted as being the “founding father” of this artistic movement that was predominant almost 100 years ago now.
A little Canada hype, since it’s turning 150 this year….
My first GIS-processed crater results are well on their way to being completely analyzed. The best MDIS and MLA data have been attained for seven Mercurian craters so far. These craters are: Abedin, Hokusai, Stieglitz, and four unnamed craters. Mercury’s “Group of Seven,” if you will.
All seven craters reside at a latitude greater than 45*N; Hokusai and Abedin are neighbours, and the four unnamed craters are also neighbours to each other; Stieglitz is the closest of the craters to the North Pole, and is located nearest to Hokusai; most of these craters can be found within 90* (E or W) of Mercury’s “Prime Meridian.”
The other craters in my list are also being prepared; unfortunately, virtually all of them have very poor MLA data and so it looks like the next best thing for me is to use the “Mercury MESSENGER Global Colorized Shaded Relief” map with a resolution of 64 pixels per degree (ppd). For comparison, the MLA imagery used for the seven craters above is at ~170 ppd while the MDIS mosaic imagery is at 256 ppd.
More of that in later updates, though….
GIS project files are currently being made for the original 13 named craters for which MDIS + MLA snippets have been obtained. The MDIS crater files were easy enough to obtain, but the corresponding MLA was trickier — north + south lat. for MDIS + MLA are the same as well as the east long., but the west long. values for MLA go from 180 to 360 instead of -180 to 0 as with the MDIS.
Once I realized that, I was able to crop out crater files from the MLA that would have the same dimensions as the corresponding MDIS files as well as be centered over the same crater (unlike in a previous post featuring John Lennon where the MLA image I thought was of Hokusai actually is not!). Then, it was a matter of making sure QGIS would actually render each MDIS + MLA image on top of each other — easier said than done!
Interestingly, I expected the two maps to be misaligned by 180* (or something similar). Instead, the maps’ boundaries aligned perfectly but the craters themselves weren’t aligned between the MDIS and MLA data-sets.
Thanks to some ISIS help from Dr. Neish, the use of “maptemplate &” in tandem with “map2map &” allowed my cropped-out craters to be properly rendered in QGIS under a sinusoidal projection centered upon the crater itself.
Abedin crater file: images match, now to get rid of those annoying polygons and to begin the actual analysis process.
Now the fun stuff can begin! Contouring the MLA file for each crater will help me determine the most likely location of each crater’s rim crest low, and from there I’ll be able to correlate to where the melt deposits are located and thus compose, hopefully, a more accurate plot of Mercury’s complex craters for comparison with the Neish et al. (2017) figure concerning the Moon and Venus.
All in due time….
After a week or so of cataloging all the unnamed craters alongside the named craters I already cataloged, as well as re-inducting several more craters I previously discarded and even obtaining a number of brand new candidates, I — at last! — have some cool new results! **and another .ppt file of craters & results to show for it….
My Mercurian crater count now is the highest it’s ever been, at 36 (19 named & 17 unnamed). The smallest crater is now an unnamed crater @ 19.93 x 63.58 with a diameter of only 16 km (the largest is still Abedin @ 116 km wide). I even have a melt flow crater now (see below)!
As for the results: “Figure 3” of Neish et al. (2017) shows how craters whose exterior melt deposits tend to coincide with their rim crest low dominate the Lunar complex craters studied, while on Venus the majority of the craters studied had their melt deposits found around 90* or greater from the low. As for Mercury, analyzing the 36 craters using JMARS has yielded the preliminary result of possessing a large number of craters in the “coincide” area (like the Moon) but also a large number in the “>90*” category (like Venus). This implies that Mercury lies intermediate to the Moon & Venus, when it comes to impact melt emplacement.
As hypothesized! Yay!
So… what does this mean? Well, my initial hypothesis here is that there could be two factors at play here: First, although Mercury has higher topography (averaged over its entire surface) than Venus it may actually have slightly lower topography than the Moon; thus, unless the Mercurian crater in question is found in a high-topography area a crater’s melt will tend to emplace more like it does on Venus — that said, there is still high topography, hence the large “coincide” value. Second, because complex craters on Mercury tend to be deeper than those on Venus yet shallower than those on the Moon it could be a matter, in some cases, of the structure of the crater itself; deeper craters on Mercury (w.r.t. crater size) may deposit melt more similarly to craters on the Moon, while shallower craters may deposit more like on Venus — where impactor direction is more important (something I’ll have to check, eventually, for Mercury by looking at the ejecta patterns about rayed craters…).
Analysis of my Mercurian craters in JMARS is a first step, to see what I’d find. Now, the real analysis begins with downloading MDIS + MLA files for each crater and compiling them all using ArcMap. That’ll keep me busy for a couple weeks, I think!
The CPSX Field School experience has just ended, and so now the Grad-school summer vacation has officially begun! Which means I can start making GIS projects for my Mercurian craters of interest….
To say this CPSX course was/is one-of-a-kind is practically an understatement. Every day feels like it goes by so quickly, yet when one wakes up the next day it feels as if the day before happened so long ago! So much generally happens each day that even when you want to return home to civilization you still hope the field school could go on for longer. Never experienced anything like it! That’s not even getting into the myriad of stops….
Being that I’m currently studying impact craters on other worlds, it was only natural that I pay special attention to the confirmed+unconfirmed craters looked at during the trip: Meteor Crater is a confirmed simple crater ~1.2 km in diameter, created mere thousands of years ago, complete with ejecta blanket and overturned strata on the south end of the rim. As for Upheaval Dome, a ~5 km wide structure of uncertain origin, because a kilometer of strata has been removed via erosion what is seen now is only the very bottom-most “roots” of whatever it was that formed this structure — there are synclinal structures, faulting (including a graben or two), steeply dipping strata, and the presence of the “Paradox Formation” present at/near the central “uplift.”
Comparing Upheaval Dome to the Onion Creek salt diapir, once again the Paradox Formation resides at the center of it all; Onion Creek strata are also steeply dipping leading up to the Paradox, but there is intense folding present in the Paradox itself and faulting appears quite rare here. Gypsum (& sometimes halides) was also found in situ in some of the Paradox units.
Other highlights include the hematite concretions at the Petrified Dunes, the eolian cross-stratification at the Grand Canyon, and the many interesting-looking cinder cones & other volcanoes (like the maar at Rattlesnake Peak) at the San Francisco Peaks area.
Because I wasn’t the only one who partook in this adventure, feel free to check out some of the other trip-goers for their own stories (assuming they post on it sometime between now & tomorrow…):
For everything else, there’s Twitter!
And now I shall return to my Mercurian craters….
As the Winter 2017 school year wraps up for me, I am soon coming up on many months of “free time” where I can really spend time on my Masters thesis — instead of any chance I can get for myself.
But, that’s still a month or so away for me…. As soon as Winter 2017 ends, CPSX field school 2017 begins; then, when I return at the middle of May, I have an annual committee meeting to tackle. Fun-fun-fun!
Blog-wise, this means that I won’t be able to post for around two weeks.
That said, here’s a small update before I disappear to Arizona:
>All named craters have MDIS (Mercury Dual Imaging System) + MLA (Mercury Laser Altimetry) files associated to them — 13 craters in all. There are still 13 or so nameless craters that need to be done.
>I’ve started gathering all the MDIS-NAC (the MDIS Narrow-Angle Camera) image files of the named craters — for use later on….
>I’m hoping to convert the files for Abedin, Hokusai, and Stieglitz to “polar-stereographic” sometime this week. I also would like to try viewing at least some of the MDIS + MLA images in ArcMap before the Field School.
>If I can, I’d like to download the MDIS + MLA for the nameless craters before I go as well….
I have also been working on my Annual Committee Meeting report, and am very nearly finished. The next thing to do now is to draft-up a presentation (more fun).
Current crater count = 14 named craters, 13 unnamed craters (27 total; removed a couple craters that weren’t viable for the study, but (re-)added a few more new + previously identified craters).
Smallest crater = Ailey @ 23 km in diameter.
Largest crater = Abedin crater @ 116 km in diameter.
1 = one melt deposit (15 craters); usually the smaller craters.
2 = two or more melt deposits (8 craters); usually the larger craters.
3 = melt inside adjacent crater (4 craters); no size preference.
In other news, I’m still not completely out of the school-work woods just yet — and I’ll be busy with school until the middle of May (June through August looks pretty free, though!); would still like to figure out how to find unnamed craters in the MDIS database, & get some craters mapped by May; also, GUI doesn’t like, so far, the MLA datasets I downloaded (I think it’s to do with the .lbl files but the GUI won’t even select them)….
That’s about it, at the present moment. Have a great Easter, all!