Last Sunday night, I had a good time looking at the Moon. I am not a Moonie in the past, but after having Obby, I am beginning to like the Moon. The Moon has actually many interesting craters, rilles, faults, Mare (Lava Sea) and other things to see. It is interesting to see how the shadows fall on the features on the Moon. With Obby, I feel that nothing on the Moon is not within reach of my scope.
It was really shiok looking at all the craterlets and ultra small features. I will buy the book ‘Atlas of the Moon’ soon. This book is a high detailed Moon Atlas and I feel this is what I would need with the power of Obby. When it comes to the Moon… I am actually a novice. I do not know the names of most of the craters and so I started identifying the craters and getting acquainted with their names. One thing about the Moon… is that the features like craters and their names..are VERY DIFFICULT TO PRONOUNCE. Most of these features like Copernicus, Aristoteles..etc are ancient famous philosophers and astronomers. I think I will also learn the Mare (pronounced ‘Maria’ meaning Sea) that will make up the ‘Rabbit’ and ‘Man’ on the moon. Hee
Ok.. I observed a few things that night. Firstly I was interested in finding out where the ‘Straight Wall’ which is a fault line along the moon that stretches about 200km. At the point of looking, it was a very noticeale dark line due to the shadow and it was real cool. It was easily seen and there were the big three crater ranges that ran parallel with it. Nice. I observed the straight wall for like 15 min and other craters near it.
The most interesting thing I observed was the crater Plato. It is 90km in diameter and it has a very smooth and dark surface. The interesting thing is that it has many small craters in them (craterlets) and these craters are really hard to see. It was a test on the telescope performance and the weather.
I have heard of it… so I went to take a peek at Plato for the first time and looking carefully at its crater bed. The seeing was bad with high winds blowing clouds and I could only use 220x magnification but it still provided great views. I could see the 4 biggest craters (2km in size.. which are real small) as 4 small rings! I have read that it is really difficult to see any craters and let alone see it resolved. I also saw 3 more other craters that were smaller and far less contrast than the big 4. It was real nice to bang 7 of them with Obby!
The craters I saw were A, B, C, D, e, f, g. The capital letters were easily resolved and seen as real craters as black pin size rings. e was also resolved as a black ring with difficulty as it was much lower in contrast. F and g were seen as white spots. I find these results were fantastic considering this is my first time looking at that crater and I did not have prior knowledge of what to expect or did I know the positions of the craters. I mentally remembered where the positions were and checked the high res Plato map after my observation.
I also did comparisons with my different eyepieces (7mm T6 and 7.5mm Ultima) and found out that my Nagler was better in many ways than my 7.5mm Ultima which is well reviewed for planets. The Nagler was just as sharp on axis and had better contrast and hence I was able to see the very small and low contrast craters f and g. I feel that the Nagler Type 6 is the best all round eyepiece and widest field eyepieces. The only problem other than cost is the 12mm eye relief. However, that is not a concern for me since I take out my specs to use it and my astigmatism don't bother me at that exit pupil size. The 7.5mm Ultima has eye relief of 6mm and I have to literally stick my eyeballs onto the lens.
I will post the picture of the crater Plato taken by a spacecraft.
Attached is what I read from an experienced observer from CloudyNights report of the craterlets in Plato (I found it in the CN forum when I was trying to find a good picture of Plato and positions of the craters):
** MAJOR CRATERLETS ON THE FLOOR OF PLATO (see attached image below)**
(Rim-to-rim diameters 1 km or larger, based on Lunar Orbiter IV images. (Plato Rim diameter from point on the cusp of the inward bowing feature north) of faulted rock (West Rim Bow-in) to east rim edge = 62 miles (99.8 km). NOTE: Letters used below are *not* standard IAU secondary crater designators.
APPROXIMATE CRATER DIAMETERS
(+/- 0.2 miles uncertainty)
The "BIG FOUR" (+1)
A = 1.7 miles (2.7 km) B = 1.5 miles (2.4 km) C = 1.5 miles (2.4 km) D = 1.3 miles (2.1 km) W (on west-northwest wall) = 2.0 miles (3.2 km)
NOTES: Although many amateurs rarely seem to see very much on the apparently smooth dark floor of Plato, the above craterlets are the ones most often reported by those lucky enough to get really good seeing. "A" is the easiest of this group due to its fairly prominent ramparts, and has been reported in a 4 to 5 inch aperture, although the unresolved "bump" of craterlet-A's ramparts is visible in only a 3.1 inch. 3 or 4 of these craterlets can sometimes be observed under low sun angle and in good to excellent seeing in apertures 6 inches and *larger*. These four can sometimes be "detected" as very tiny white spots in 3 to 5 inch scopes during the full moon, although to show them all as true pits often requires a 7 or 8 inch aperture. The "East Wall Pit" is a much larger irregular feature (4 miles across) which often hides in the shadow of the eastern wall during the lunar mornings. It may or may not be an impact crater. There is also a small nearly rimless craterlet "W" low on the west-northwest wall north of the west-rim bow-in which is about 2 miles across. It is considerably more difficult to observe than its size would indicate, as the sun has to be at just the right angle to allow any shadow to fill even part of it to make it visible.
The "Little Four"
e = 1.2 miles (1.9 km) f = 1.0 miles (1.6 km)
g = 0.94 miles (1.5 km) h = 1.4 x 0.8 miles (2.2 x 1.3 km)
NOTES: Craterlet-e has been sighted in a good 8 inch, but craterlet-f may take a bit larger scope to see with any regularity. "e" tends to hide in the long early morning shadows, as "f" does also in the low lunar evening. The Lunar Orbiter shots of Plato show that "h" is a tiny double craterlet with 0.9 and 0.8 mile diameter components, forming an elongated 1.4 x 0.8 mile feature visible in larger apertures, but not fully resolved. Again, very high lunar sun may allow some of these cratelets to be "detected" as tiny white spots near full moon. The "Big Four", and the "Little Four" probably represent most of the craterlets on the floor of Plato which might be visible to amateurs using moderate to large apertures under excellent seeing.
The "Tiny Nine"
i = 0.7 miles (1.2 km) j = 0.6 miles (1.0 km) k = 0.7 miles (1.3 km) l = 0.6 miles (1.0 km) m = 0.7 miles (1.2 km) n = 0.7 miles (1.1 km) o = 0.7 miles (1.1 km) (double craterlet) p = 0.7 miles (triple craterlet) q = 0.6 miles (1.0 km) (double overlapping crater)
NOTES: These are *extremely* difficult to observe even in large apertures as anything other than tiny white spots or rimless pits, although i, j, m, and o2 have been imaged by Maurizio Di Scuillo using a CCD camera on a ten inch Newtonian optimized for high resolution planetary work. Craterlet k has a very small pit to its west and will be tough to resolve easily. Craterlet m is a fairly shallow bowl with little in the way of a rim, so it is more difficult than its size would indicate. "n" is a very small rimless pit just to the east of a tiny white spot which is often mistaken for a crater (may be a small mound or ejecta blanket). Craterlet o is a double craterlet, which forms a 1.3 mile x 0.7 mile elongated feature. p is a triple, consisting of 0.7 mile, 0.6 mile, and 0.3 mile craterlets in close promimity, which might be detectable in very large apertures as a single almost rimless 1.5 mile x 0.7 mile feature (not resolved). Craterlet q is two very small overlapping craterlets which form a single 1.3 mile x 0.6 mile feature. Lunar Orbiter images show a large number of smaller pits down to 0.25 miles across on the floor of Plato, but the above three "families" are probably the only ones which have much of a chance of being seen visually from Earth.
Mysteries of Plato
