The final issue of the BAA Lunar Section’s magazine “The New Moon” (TNM) is available online now.
Sketch by Harold Hill, from The New Moon, Vol. 1, No. 4
The New Moon is produced by the Topographical Sub-section of the Lunar Section of the British Astronomical Association and makes an appearance twice every year. It contains articles about the Moon and its observation and features lunar images and observational drawings.
The first issue was published more than a quarter of a century ago, back in May 1982, and the latest edition will be the final one, to be replaced by a new annual bulletin “The Moon: Notes and Records of the BAA Lunar Section”, the first issue of which will appear next year.
Bill Leatherbarrow, BAA Lunar Section Director says: “TNM has served the Section well for over a quarter of a century, but it was becoming difficult to separate its function from that of the enlarged monthly Circular, which now publishes the majority of the current observations submitted to the Section.
There will be more about the new bulletin in a forthcoming LSC, but in the meantime I would like to thank Peter Grego on behalf of the Section for the fine work that he has put into producing TNM over the past few years. His skills are now deployed on the monthly LSC, but we shall also draw upon his experience and expertise as an editorial advisor to “The Moon”.”
The image above, from the cover of the final issue of The New Moon, features a classic observation by one of the
BAA Lunar Section’s finest — the late Harold Hill, whose lunar observational work serves as a source of inspiration to a new generation of amateur astronomers and remains a valuable source of reference to visual observers. The observation featured in The New Moon, Vol. 1, No. 4, p124
This blog post is part of our regular “Saturday Circulars“, in which we will highlight a news article from one of the BAA sections’ newsletters. This article was written by Dr Tony Cook. It appears in Lunar Section Circular Vol. 47 No. 7 July 2010.
As we head into the Summer, the Moon will be grazing tree tops, below the horizon, or more than likely it will be cloudy. Fortunately there is a new on-line lunar science activity web site that will provide vital crater statistics for planetary geologists, help decide upon safe landing sites for future space missions, and above all should be a lot of fun to use. The web site is: http://www.moonzoo.org/ To use MoonZoo it you will have to set up initially a username and password. Once you have logged in, there are lots of help pages, and even videos that you can watch instructing you in the use of MoonZoo. There are two primary science activities that you can do with MoonZoo: a Crater Survey, and Boulder Wars.
Crater Survey
This lets users place and fit initially circles to craters. Once an orange circle has been placed it can be clicked on and adjusted in position, size and even ellipsoidal shape and angle to give a better fit. If you see boulders within the crater then you can click on the ‘boulder’ button and classify the crater as having ‘none’, ‘some’, or‘many’ boulders. There is also an ‘interesting feature’ button and this allows users to place a purple rectangle around anything that they find interesting and want to highlight for planetary scientists to take a look at later — the options are a bit limited: ‘Spacecraft Hardware’, ‘Craters’ (Bench/Mound/Pit, Dark Haloed, Fresh White, Elongate Pits), ‘Linear Features’ (Boulder Tracks, Crater Chain, Sinuous channels, Other Linear Feature), all with simplified subsections, and of course the ‘Others’. If you find an image particularly interesting, and want to find where it is on the Moon then you can save this as one of your favourites.
MoonZoo: Crater Survey
Boulder Wars
This is a much simpler and faster tool. It aims to compare two images at random to see which has the most boulders if any? Boulders are important to future lunar surface exploration plans as landing spacecraft need to avoid touching down on boulder areas as this could topple a spacecraft over. The image below shows an example; there are three buttons, the one on the left should be pressed if you think this has the most boulders, else the one on the right, and in some cases the central button will be more appropriate.
MoonZoo: Boulder Wars
Science and Exploration Issues
One of the main questions that scientists want to address is how old is the surface of different parts of the Moon? An older surface will have been exposed to meteorites for a longer duration than younger lava covered surfaces. Therefore the older a surface is, the higher its crater count. So far nobody has taken crater count statistics into the realm of very small craters, therefore this is a new research area. Planetary scientists are also interested in how to identify whether a crater is secondary impact in origin.
Again user measured positions with respect to large diameter craters, and ellipticity, may help us to discriminate between these in future. On the subject of boulders, apart from mapping areas that might be a landing hazard, we also do not understand why some lunar regions have more boulders than others — again statistics collected here will assist theories.
Statistics
MoonZoo relies upon ordinary members of the public and amateur astronomers. By fielding out the problem to the entire world, we can make rapid progress. According to the Oxford University team who host the MoonZoo web site, in the month since it was launched on 11th May 2010, it was visited by almost 90 thousand users. Of these 20 thousand participated in measurements and just over a million craters and areas of interest have been measured/marked distributed across 150 full size LROC images. You can see who is currently active on MoonZoo and where their geographical location on: http://www.moonzoo.org/live . One of the great things about MoonZoo measurements of craters is that it is not just possible to measure crater diameters, but also perhaps how degraded a crater is? If you had a clearly defined rim then all users will come within a few meters in agreeing on its diameter. If the crater rim is highly degraded then the measurements provided by the public will have a lot more disagreement. Therefore the standard deviation on diameter measurements may be used possibly to infer the degradation state of the crater. Similarly for boulders, if the two images presented have similar numbers of boulders, then the statistics that about half the users will pick one image, and half the other — so again giving a good measure of similarity between two scenes.
What amateur astronomers can do
Although the website is designed for the public, amateur astronomers can get a lot out of this too. Apart from the obvious decision of what to do on cloudy nights, the images presented let you explore the Moon at a spatial scale a thousand times better than you can achieve from Earth or from LTVT simulations. You can also start cataloguing any interesting features, an example is shown on ‘Image of the Week’. There is also a user forum where you can advise members of the public that are having problems interpreting images or using MoonZoo, or you can discuss lunar matters with professional planetary geologists. Above all, this is really an excellent forum for encouraging others to take up Earth-based lunar observing. So please have a try at MoonZoo and send in your experiences or any interesting features found for discussion into the Lunar Section Circular.
This blog post is the first of our regular “Saturday Circulars“, in which we will highlight a news article from one of the BAA sections’ newsletters. This article was written by Phil Morgan, a longstanding member of the BAA Lunar Section. It appears in Lunar Section Circular Vol. 47 No. 6 June 2010.
Plato’s Hook
In his famous book The Moon H.P. Wilkins shows an observation of Plato crater made with the Meudon 33-inch refractor, dated 3 April 1952. This detailed study shows a curious hook shape in the shadow falling from the inner east rampart of the crater.
Wilkins’ published observation of Plato and the ‘hook’ made at Meudon and taken (courtesy Bill Leatherbarrow) from Wilkins’ recently discovered notebooks.
Wilkins' original observational sketch of the 'hook'
Many believed that this was a mistake by Wilkins, but on 3 May 2009, Maurice Collins (Palmerston North, New Zealand) secured a series of images that seemed to confirm Wilkins’ findings.
Maurice Collins produced LTVT simulations of Plato as it appeared on 22 April (for 21:15 UT, above), which confirm that the hook effect is very short lived, hence the dearth of confirmatory observations by other observers.
On 22 April this year I made an observation of Plato that also shows this strange hook effect to the inner shadow profile. The observation commenced at 21:15 UT when the ‘hook’ looked very pronounced. By 21:30 UT the effect had diminished, but was still decidedly hooked in shape.
Phil Morgan's observational sketch of Plato's 'hook' from2010 April 22 at 21:15UT
I passed this observation on to Maurice Collins, who was, naturally very pleased to see confirmation of his own study. Utilising Jim Mosher’s excellent LTVT programme, Maurice produced a couple of simulations of the shadow profile for the timing of my observation.
The results are interesting and do appear to confirm the hook effect. The first one timed for the start of my observation, shows the hook effect clearly, and the second timed for the finish 15 minutes later, confirms my findings that the hook had started to diminish and that the effect is a very short lived one — hence the lack of confirmation by most other observers.
It is difficult to say just what causes this hook in the shadow profile on the floor of Plato, but it could be down to the shadow sometimes falling into a small circular depression on the crater floor. In his other book Our Moon, Wilkins shows the same observation, but with the hook less pronounced, but just why he did this no one knows!
I also asked Colin Ebdon if by any chance he had been observing Plato on 22 April. Unfortunately, not specifically, but he did happen to take two images of Plato shortly after my observation finished — the first at 22:00 UT and the second at 22:26 UT. These are interesting to me since they confirm the general shadow profile that I had recorded a bit earlier, a pity that he didn’t image the region 30 minutes earlier!
Colin Ebdon’s image of Plato on 2010 April 22 at 22:26 UT.
To find out more about the BAA Lunar Section see our previous blog post: About the BAA: Lunar Section
@britastro