18 replies to this topic

[jonbosley]

Tycho can exhibit a strange blurring effect around part of the outer rim. It can be seen both visually and in some high resolution images. I decided to investigate the causes of this as it is a trait shared by only a few craters and was captured in one of my higher resolution images. 
The craters blurred-looking ejecta is the result of its extensive secondary cratering and ballistic sedimentation from the impact that created it. When Tycho formed, it released a massive volume of ejecta at high velocities, scattering debris far across the lunar surface. This material settled in uneven layers, creating the characteristic rays and diffuse ejecta blanket seen around the crater.

 

Ballistic Sedimentation: Ejecta was expelled and then settled in overlapping layers, softening the boundaries of individual fragments and creating a somewhat diffused effect that can be seen. 
 

Optical Effects & Space Weathering: Over time, micrometeorite impacts and exposure to the harsh space environment cause gradual changes to the regolith, slightly modifying the initial contrast between bright ejecta and the darker lunar surface.

 

Imaging Resolution & Angle: Some photos—especially when taken under certain lighting angles—can emphasize the diffuse nature of the ejecta, making the blurring effect more pronounced. 

 

Other craters that can show this effect are:

1. Copernicus
2. Aristarchus
3. Kepler
4. Proclus
5. Jackson (A far-side crater)

Take a look through some of your images to see if you can identify this effect. 
Here is my image of Tycho taken with the 18”, to the east are two melt pond. 
Jon.

 

[scottinash]

This is a very interesting post, Jon!  Your image is showing the "phenomenon" extremely well.   Thank you for sharing.

 

One of the most detailed orbital images of Tycho that I recall was taken by the LROC (bottom of the page); I downloaded the full 167M tiff to my SSD back in 2017 when I first ran across the article.   Notice that there are "blurred" areas in this image as well.

 

You can also see the "blurring" in this LROC "North Flank" image.

Edited by scottinash, 24 May 2025 - 09:19 PM.

[Physicsman]

Good post, Jon. There have been times when I've wondered what the "problem" is with my image processing in the Tycho area because of that very issue.

 

Here are 2 images, taken on consecutive nights in April, which also show this. I think the April 8 image, at lesser phase and less dominating bright rays, shows the effect better.

 

April 08, 2025: 19.57 UT

 

 

April 09, 2025: 22.15 UT

 

[jonbosley]

 

Good post, Jon. There have been times when I've wondered what the "problem" is with my image processing in the Tycho area because of that very issue.

 

Here are 2 images, taken on consecutive nights in April, which also show this. I think the April 8 image, at lesser phase and less dominating bright rays, shows the effect better.

 

April 08, 2025: 19.57 UT

 

 

 

April 09, 2025: 22.15 UT

 

Thanks Jeff, first time I came across this I thought I had an issue as well, with dust bunnies on my optics. It can be quite subtle and on other occasions more pronounced with angles and lighting having a direct effect upon the crater and the level of blurring seen. 
 

Jon

[jonbosley]

This is a very interesting post, Jon!  Your image is showing the "phenomenon" extremely well.   Thank you for sharing.

 

One of the most detailed orbital images of Tycho that I recall was taken by the LROC (bottom of the page); I downloaded the full 167M tiff to my SSD back in 2017 when I first ran across the article.   Notice that there are "blurred" areas in this image as well.

 

You can also see the "blurring" in this LROC "North Flank" image.

Thanks Scott, the LROC was an original source for this that I found. 
 

It does make you wonder if at least some of the reported TLP’s that have been historically reported are linked to ejecta blurring. Especially as it can seem some what transient, visually through the telescope lasting a few hours or a few days depending on angles and lighting. 
 

Having said that it only seems to be contained to young craters though it is plausible that the list could be expanded in the future.

 

Jon

[macpurity]

One of the true benefits of this corner of CN is the “I made you look” component. Several very interesting papers have been published about Tycho’s ejecta blanket. You might lack access to the full PDF of this 2016 article, but the abstract and summary are indeed interesting and applicable to the topic.

[Physicsman]

Scott has done some further digging around in my recent images and suggested I post some examples of ejecta blurring that are non-Tycho,

 

So here goes - note that all these examples have prominent crater rims with large surrounding ejecta blankets (though not all create ray systems)...

 

Copernicus: 19.30 UT April 08 2025

 

 

Bullialdus: 19.28 UT April 08 2025

 

 

Macrobius 00.50 UT September 21 2024 

 

 

Aristillus: 18.53 UT March 09 2025

 

 

Kepler: 22.08 UT April 09 2025

 

 

Aristarchus: 22.11 UT April 09 2025

 

Edited by Physicsman, 26 May 2025 - 11:31 AM.

[jonbosley]

 

Scott has done some further digging around in my recent images and suggested I post some examples of ejecta blurring that are non-Tycho,

 

So here goes - note that all these examples have prominent crater rims with large surrounding ejecta blankets (though not all create ray systems)...

 

Copernicus: 19.30 UT April 08 2025

 

 

 

Bullialdus: 19.28 UT April 08 2025

 

 

 

Macrobius 00.50 UT September 21 2024 

 

 

 

Aristillus: 18.53 UT March 09 2025

 

 

 

Kepler: 22.08 UT April 09 2025

 

 

 

Aristarchus: 22.11 UT April 09 2025

 

Great job! The interesting one in the samples has to be Macrobius as it dates from the “Lower Imbrian epoch”. This, if correct, would challenge the current ejecta blurring time scaling. 
 

Jon.

[Physicsman]

Great job! The interesting one in the samples has to be Macrobius as it dates from the “Lower Imbrian epoch”. This, if correct, would challenge the current ejecta blurring time scaling. 
 

Jon.

Cheers, Jon. 

 

I'll leave you to pursue the Macrobius issue. It certainly has the trademark ejecta ring blurring.

 

I presume that in the absence of the glassy ejecta, the light striking the surface is regularly reflected producing a coherent image. But glassy material ejected onto the surface scatters the light in more random directions creating the blurring effect.

 

I also assume that the blurring will only occur with complex craters above a certain size - large enough to have substantial rims of excavated material. I'm not a "geologist" so I'm likely whistling in the wind.

 

Irrespective, every feature we observe adds extra interest when new images/observations are made.

[jonbosley]

Cheers, Jon. 

 

I'll leave you to pursue the Macrobius issue. It certainly has the trademark ejecta ring blurring.

 

I presume that in the absence of the glassy ejecta, the light striking the surface is regularly reflected producing a coherent image. But glassy material ejected onto the surface scatters the light in more random directions creating the blurring effect.

 

I also assume that the blurring will only occur with complex craters above a certain size - large enough to have substantial rims of excavated material. I'm not a "geologist" so I'm likely whistling in the wind.

 

Irrespective, every feature we observe adds extra interest when new images/observations are made.

Jeff,

Size wise Proclus is 26.9km and is a know blurring ejecta crater, so there is some variation in this. It would be interesting to find smaller craters that exhibit the effect if any exist. Here are a few more know blurring related origins:

Factors Amplifying Blurring

   Impact Velocity: Higher velocities (e.g., cometary impacts) spread ejecta farther, increasing blurring. 
   Target Material: Loose regolith (vs. bedrock) produces more diffuse ejecta.

 

Ejecta smearing:

From LRO Studies, Crater “ Giordano Bruno” (Copernican, near-vertical) shows sharp ejecta rays, while oblique craters like “Proclus”(15° angle) exhibit asymmetric, smeared ejecta.

 

Jon

[Physicsman]

Interesting comment about the oblique impact craters.

 

I just had a look at some very high res LRO images of Messier and Messier A.

 

I can almost convince myself that Messier A, diameter 10.6km, has ejecta blurring, though it may be that the rim consists of darker excavated material (like halo craters) and the material is much less reflective and contrasts with lighter basalts in the mare.

 

I remember one of the key arguments put forward by the volcanic crater origin supporters (mostly Europeans!) was how improbable it was that circular craters could be created by oblique impacts. Since most impacting bodies, by chance, will hit obliquely they felt secure in their arguments. As far as relevance to ejecta blurring, maybe velocity of impactor may be the key, so small size-high velocity could give us Proclus, Aristarchus type objects, but larger size-high velocity would give us larger craters like Tycho and Copernicus.

 

Too many variables to get my head round, but it does seem that ejecta blurring is quite common.

Edited by Physicsman, 26 May 2025 - 07:27 PM.

[scottinash]

In January 2024 I noticed blurring in an image by Jeff (Physicsman) of Theophilus and Madler which we were analyzing for a project.  Initially, we considered if the blurring may have been the result of an earth based contrail, but that would have dissipated and/or moved considerably over a stacked multi-frame image.  Jeff, re-processed the image to rule out any artifact, etc. but the results continued to reveal these "soft" patches.

 

I opened my copy of the recent Chinese Geologic Map of the Moon to see if it indicated anything of interest for these two craters and it validated the blankets.  It does seem a possibility that any crater with a distinct ejecta blanket, regardless of the period, may have the unique material characteristics present to cause the diffuse optical results.

 

 

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[Physicsman]

You've got a very good memory, Scott. I recall apparent blurring in the Mons Penck area moving across Theophilus crater and thought it was a con trail effect, an idea we later rejected.

 

That image is one I haven't re-processed using BiggSky but it's very effective at illustrating the ejecta blurring. I know we imagers (you are excused, as a visual observer!!) often look for excuses when things don't work quite as well as we expected, but these ejecta effects are genuine and widespread.

 

The Chinese map is a very useful resource to correlate ejecta and blurring. Good post.

[RobDob]

In January 2024 I noticed blurring in an image by Jeff (Physicsman) of Theophilus and Madler which we were analyzing for a project.  Initially, we considered if the blurring may have been the result of an earth based contrail, but that would have dissipated and/or moved considerably over a stacked multi-frame image.  Jeff, re-processed the image to rule out any artifact, etc. but the results continued to reveal these "soft" patches.

 

I opened my copy of the recent Chinese Geologic Map of the Moon to see if it indicated anything of interest for these two craters and it validated the blankets.  It does seem a possibility that any crater with a distinct ejecta blanket, regardless of the period, may have the unique material characteristics present to cause the diffuse optical results.

Scott got me thinking about overlaying the Chinese Geo map over an LTVT 3D simulation of Tycho, to visualize the distinct area of ejecta relative to time period. The time scale indicates newer ejecta material (<0.8 billion years) overlaid on to Pre-Nectarian materal (>3.85 billion years).

 

Fascinating, Captain!

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Edited by RobDob, 28 May 2025 - 12:49 PM.

[Physicsman]

That's worked well, Rob.

 

Not surprisingly, the "blur zone" correlated nicely with the ejecta region. What's more interesting is that the blurring areas don't show up OUTSIDE the main ejecta region, so the tentative conclusion is that ejected material - either it's colour, chemical make-up, or surface texture is our prime suspect.

 

I guess a knowledgeable 5 year old would tell me "well, that's obvious. Isn't it?!"

Edited by Physicsman, 28 May 2025 - 01:06 PM.

[jonbosley]

In January 2024 I noticed blurring in an image by Jeff (Physicsman) of Theophilus and Madler which we were analyzing for a project.  Initially, we considered if the blurring may have been the result of an earth based contrail, but that would have dissipated and/or moved considerably over a stacked multi-frame image.  Jeff, re-processed the image to rule out any artifact, etc. but the results continued to reveal these "soft" patches.

 

I opened my copy of the recent Chinese Geologic Map of the Moon to see if it indicated anything of interest for these two craters and it validated the blankets.  It does seem a possibility that any crater with a distinct ejecta blanket, regardless of the period, may have the unique material characteristics present to cause the diffuse optical results.

Scott, Theophilus does seem to show a level of blurring, checking LROC images I can also see some and in my own images of it as well. I have crossed checked LROC data to confirm the phenomena with certain craters. 
​

Potential Sources of "Blurring" Misinterpretation.

- Diffuse Secondary Ejecta: Some older telescopic images (e.g., Apollo-era) can show ejecta rays as less distinct due to imaging resolution limits of the time, creating a "blurred" impression. Modern LRO data reveals they are actually crisp but asymmetrically distributed as in the case of Messier A.

-Degradation Over Time: Some ejecta has darkened from space weathering, which could soften their contrast against the mare, but this affects all directions equally .

Plato is an intriguing example. 
​Formed ~3.84 billion years ago during the Upper Imbrian period. 
My image show quite extensive blurring especially to the east as well as some to the north, west and south. Cross checking with the LROC data the image seems to confirm some blurring west, north and especially east and some to the south. 
Compared to Copernicus age craters this could plausible be a result of degradation over time. 
Jon

[RobDob]

Scott, Theophilus does seem to show a level of blurring, checking LROC images I can also see some and in my own images of it as well. I have crossed checked LROC data to confirm the phenomena with certain craters. 
​

Potential Sources of "Blurring" Misinterpretation.

- Diffuse Secondary Ejecta: Some older telescopic images (e.g., Apollo-era) can show ejecta rays as less distinct due to imaging resolution limits of the time, creating a "blurred" impression. Modern LRO data reveals they are actually crisp but asymmetrically distributed as in the case of Messier A.

-Degradation Over Time: Some ejecta has darkened from space weathering, which could soften their contrast against the mare, but this affects all directions equally .

Plato is an intriguing example. 
​Formed ~3.84 billion years ago during the Upper Imbrian period. 
My image show quite extensive blurring especially to the east as well as some to the north, west and south. Cross checking with the LROC data the image seems to confirm some blurring west, north and especially east and some to the south. 
Compared to Copernicus age craters this could plausible be a result of degradation over time. 
Jon

IMG_2599.jpeg
IMG_2598.jpeg

Jon, I think I can back up your blurry Plato ejecta with this cropped image I took 12-23-2023. Got to thinking if there is any detectable color associated with aged ejecta material, so I cranked up the saturation in my image and you can see a noticeable difference (from my ASI678MC camera) within the ejecta blanket.

 

Edit: I've seen this effect on Mineral Moon images as well.

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Edited by RobDob, 29 May 2025 - 01:45 PM.

[jonbosley]

Jon, I think I can back up your blurry Plato ejecta with this cropped image I took 12-23-2023. Got to thinking if there is any detectable color associated with aged ejecta material, so I cranked up the saturation in my image and you can see a noticeable difference (from my ASI678MC camera) within the ejecta blanket.

 

Edit: I've seen this effect on Mineral Moon images as well.

That is excellent Rob! From the geo map, I notice that the ejecta blanket extends a ways into Mare Imbrium, yet visually we do not detect it. This must be a result of later Eratosthenian Period (3.2–1.1 Ga) flooding.  Younger lava flows, particularly high-titanium "blue" basalts, erupted sporadically. 

[Physicsman]

Isn't it wonderful that an initial post on potential "blurring" observed in high-resolution images of one locale on the Moon can expand to include multiple regions and bring in the events that occurred over Geologic time?

 

I enjoy lunar imaging immensely, but on numerous occasions this particular CN thread has brought out much more than what's in "plain sight".

 

Well done, guys. And I'm delighted to see those Plato images. Superb quality and confirming that my "blurring" worries had an explanation of lunar origin. Great stuff!