Jump to content

  •  

CNers have asked about a donation box for Cloudy Nights over the years, so here you go. Donation is not required by any means, so please enjoy your stay.

Photo

Curious secondary crater chain on the glacis of Bullialdus

  • Please log in to reply
8 replies to this topic

#1 RadioAstronomer

RadioAstronomer

    Vostok 1

  • *****
  • topic starter
  • Posts: 160
  • Joined: 13 Jun 2018
  • Loc: Ft. Lauderdale, FL

Posted 22 May 2019 - 11:47 PM

Dear all,

It is an interest of mine to visually observe features described by the classic telescopic selenographers, particularly Goodacre, and Wilkins & Moore. You would be surprised to see how many of the features that they describe can not be seen in spacecraft-based imagery. Many of these features have been claimed to be product of the imagination of the observers, specially in the case of Wilkins. I don't believe that it is always the case, or at least it's not that simple.

An example of such feature is a secondary crater chain on the glacis of Bullialdus first observed by Goodacre. The chain runs from Bullialdus to König (formerly called Bullialdus C). This chain is almost invisible in Lunar Reconnaissance Orbiter imagery (third panel). Interestingly, the right conditions of illumination render it visible for telescopic observers, as the attached LTVT DEM simulation shows (central panel).

Here is what Goodacre had to say about this feature: 

"From near the break in the S.E. wall of Bullialdus and extending towards C (now called König) is a chain of craterlets not shown on any previous map and absent from the M. Willson photograph. This is not a difficult object and should be looked for when the morning terminator is near Hippalus. It was first seen in 1929 April 18 and subsequently 1931, May 26. The chain of craters diminish in size as it proceeds towards C before reaching which it fades out as a cleft." Also see Goodacre's drawing of the area as it appeared in his classic book "The Moon: With A Description Of Its Surface Formations" (first panel).

Wilkins & Moore said: "Between König and Bullialdus are two oval, ridge-bordered enclosures, traversed by craterlet chains resembling clefts".

Anyway, in this day and age it is often claimed that everything on the Moon has been photographed and there is nothing left or new to see with an Earth-based telescope. The continuously changing angle of illumination on the lunar surface makes such statement not entirely accurate. I would say that yes, the Moon has been measured in it's entirety with spacecraft-based laser altimetry, but some features have yet to be photographed/observed.  This post is to encourage observers to chase these features.

 

Kacper

 

 

Attached Thumbnails

  • Screen Shot 2019-05-23 at 12.32.58 AM.jpg

  • Jim Curry, AllanDystrup, photomagica and 2 others like this

#2 Tom Glenn

Tom Glenn

    Surveyor 1

  • -----
  • Posts: 1649
  • Joined: 07 Feb 2018
  • Loc: San Diego, CA

Posted 23 May 2019 - 02:27 AM

You would be surprised to see how many of the features that they describe can not be seen in spacecraft-based imagery. 

A very interesting post, but your comments regarding the inability of features to be seen by spacecraft imagery is misleading and inaccurate.  The image you posted above from the LRO mosaic poses several problems.  First, it is an extreme reduction in size of the raw data, presented above at an image scale that has significantly less resolution that what amateur images show.  Second, the solar illumination angle is not suitable to see the feature you describe.  The readily available LRO images are somewhat limited in lunar phase, but if you wanted to find better images of the feature you would have to comb through the raw data, which is also publicly available, but could take quite some time.  But even using the LRO Quickmap, we can easily select the "Big Shadows" feature, as well as change the angle of view to obtain the image below, which contains many small craterlets that could be a part of the described feature.  However, even this image is limited in phase, and also presented at a severely restricted image scale, with the raw data reporting meter level information.  

 

LRO_screenshot.jpg


  • happylimpet and Steve Cox like this

#3 beggarly

beggarly

    Viking 1

  • -----
  • Posts: 689
  • Joined: 12 Jun 2015
  • Loc: Belgium

Posted 23 May 2019 - 03:10 AM

Image from Lunar Orbiter (1966 - 1967):

 

https://www.lpi.usra.../info.shtml?341

 

https://www.lpi.usra...g/iv_125_h1.jpg

 

Bullialdus on LPOD (The Moon Wiki): https://the-moon.us/wiki/Bullialdus


Edited by beggarly, 23 May 2019 - 03:16 AM.

  • raidambrosio likes this

#4 RadioAstronomer

RadioAstronomer

    Vostok 1

  • *****
  • topic starter
  • Posts: 160
  • Joined: 13 Jun 2018
  • Loc: Ft. Lauderdale, FL

Posted 23 May 2019 - 03:18 AM

Dear all,

Thanks for providing these images. I stand corrected in the case of this particular feature. 

How about the feature described in this post? 

https://www.cloudyni...ear-grimaldi-c/



#5 Tom Glenn

Tom Glenn

    Surveyor 1

  • -----
  • Posts: 1649
  • Joined: 07 Feb 2018
  • Loc: San Diego, CA

Posted 23 May 2019 - 11:58 AM

Dear all,

Thanks for providing these images. I stand corrected in the case of this particular feature. 

How about the feature described in this post? 

https://www.cloudyni...ear-grimaldi-c/

I just posted in your other thread.



#6 RadioAstronomer

RadioAstronomer

    Vostok 1

  • *****
  • topic starter
  • Posts: 160
  • Joined: 13 Jun 2018
  • Loc: Ft. Lauderdale, FL

Posted 23 May 2019 - 12:34 PM

I just posted in your other thread.

Just saw it. I hope you will agree that even my flimsy picture taken with a 4" scope + iPhone makes the swelling/structure considerably more obvious (due to the cast shadow) than the LROC composite, which is basically the point of this whole thread. 


Edited by RadioAstronomer, 23 May 2019 - 12:35 PM.


#7 Tom Glenn

Tom Glenn

    Surveyor 1

  • -----
  • Posts: 1649
  • Joined: 07 Feb 2018
  • Loc: San Diego, CA

Posted 23 May 2019 - 05:52 PM

Just saw it. I hope you will agree that even my flimsy picture taken with a 4" scope + iPhone makes the swelling/structure considerably more obvious (due to the cast shadow) than the LROC composite, which is basically the point of this whole thread. 

We might just be arguing semantics here.  I do agree that your image shows a more pronounced shadow.  But I don't agree with your conclusion that somehow you are seeing something that spacecraft imagery cannot see.  Perhaps that was not your intention, but that is what you wrote.  

 

The LRO Quickmap is a publicly available, interactive map, but it is limited in phase.  Because of those limitations, it will not show you every possible feature under changing illumination.  But that doesn't mean the raw data isn't there.  It is absolutely there, but you have to know how to access the information.  In fact, NASA has an entire department dedicated to displaying data in an interactive way (The Visualization Studio).  Starting with only terrain elevation data, you can create an extremely accurate 3D map of the Moon.  In the imaging forums, there are people that have used their own images to overlay on a detailed terrain map to create a rotatable 3D image of the Moon.  Although it is fun to think of your own image being used to "color" the NASA data, all of the detail in those images comes from NASA spacecraft data.  

 

If your general point was simply that we can observe features by eye that are not obvious from studying satellite data, then I completely agree, because the satellite data one is looking at likely has a different perspective and solar angle.  Even if this wasn't the case though, the desire to observe the Moon as a hobby completely transcends any practical scientific value.  Despite the fact that the entire lunar surface has been mapped with exquisite detail, I still enjoy imaging the Moon with my amateur equipment simply for fun.  



#8 Crusty99

Crusty99

    Mariner 2

  • -----
  • Posts: 240
  • Joined: 07 May 2018

Posted 26 May 2019 - 02:37 AM

Dear all,

It is an interest of mine to visually observe features described by the classic telescopic selenographers, particularly Goodacre, and Wilkins & Moore. . . .

Here is what Goodacre had to say about this feature: 

"From near the break in the S.E. wall of Bullialdus and extending towards C (now called König) is a chain of craterlets not shown on any previous map and absent from the M. Willson photograph. This is not a difficult object and should be looked for when the morning terminator is near Hippalus. It was first seen in 1929 April 18 and subsequently 1931, May 26. The chain of craters diminish in size as it proceeds towards C before reaching which it fades out as a cleft." Also see Goodacre's drawing of the area as it appeared in his classic book "The Moon: With A Description Of Its Surface Formations" (first panel).

Wilkins & Moore said: "Between König and Bullialdus are two oval, ridge-bordered enclosures, traversed by craterlet chains resembling clefts".

 

Kacper

 

Kacper, thank you for sharing your interest in classic selenographers. The quotes certainly add a dimension to your post. Below are two references I located on Walter Goodacre.

  • Article on Walter Goodacre, written by Thomas A. Dobbins, published in Biographical Encyclopedia of Astronomers (2005, Springer, Vol. 1, p. 429). Dobbins co-authored the book Epic Moon with William P. Sheehan (2001, Willmann-Bell).
     
  • Obituary of Walter Goodacre, published in the Journal of the British Astronomical Association, 49 (1): 38–40. 1938, available online at SAO/NASA Astrophysics Data System (ADS).


#9 CounterWeight

CounterWeight

    Star walker

  • *****
  • Posts: 10642
  • Joined: 05 Oct 2008
  • Loc: PDX, OR.

Posted 27 May 2019 - 12:13 PM

Certainly makes a case for giving the illumination angle or phase it's proper due when describing an observation and or comparing to imagery. 




CNers have asked about a donation box for Cloudy Nights over the years, so here you go. Donation is not required by any means, so please enjoy your stay.


Recent Topics






Cloudy Nights LLC
Cloudy Nights Sponsor: Astronomics