Anyone who has ever gazed through a telescope at the lunar surface has beheld a world of great desolation. From the giant mountain ranges and valleys – to the vast open lava plains of the lunar seas and oceans – to the great impact craters that cover almost the entire lunar surface. These regions have always fascinated me – as I am sure they have fascinated you as well.
Of the many observable sites on the lunar surface, I find the following some of the best that I have had the pleasure of viewing in the eyepiece.
The Apennine Mountains
The Apennine Mountains are one of the most pristine mountain ranges, and certainly one of the most beautiful ranges on the lunar surface. The Apennine Mountains or (Montes Apenninus) is best observed near the first and last quarter moon. It spans an area of about 600 km along the south east shore of Mare Imbrium. This amazingly jagged range of mountains is the pinnacle of beauty especially when viewed through a 6 or 10 inch aperture telescope operating at 250x during a low Sun, this wondrous region is made up of a varied collection of mountain peaks, ridges, and valleys.
The Apennines are a little over 3800 million years old. They are the direct result of a large asteroid striking the lunar surface, which created the Imbrium basin. This giant impact caused the highland crust bordering the southeastern shore of Mare Imbrium to rise abruptly, forming this magnificent range.
The crater Conan
Near the northern most regions of the Apennines is the crater Conan, which is around 22km in diameter, it is the small crater sitting right in the middle of the range.
Here we find a small area of Mare Imbrium that extends a few kilometers north. This area is called Palus Putredinus or the “Marsh of Decay”. In my 14 inch Cassegrain operating at 300x you can see very fine cracks or rilles on the surface of this area. This is the region were the Apollo 15 crew took rock samples from the Hadley Rille.
The crater Eratosthenes
Moving south along the Apennine ridge, we come to a fairly large crater known as Eratosthenes. This crater is approx 58km in diameter, and is a fine example of a pristine crater. She has well defined terraces in her walls, which can be seen very well in a low Sun. Eratosthenes rises about 2.4km above the surrounding lunar floor.
The crater Copernicus
Located not far from the crater Eratosthenes, is the crater Copernicus. We find Copernicus floating in the Oceanus Procellarum “The Ocean of Storms”. This crater is one of the most photographed craters on the Moon. Copernicus is 93km in diameter, and is best observed just before the first and last quarter moon. When observing this magnificent crater you will notice the well defined terraces in the crater walls. These terraces were created when titanic forces were released by the impacting meteor. These forces were equal to the energy released by 20 trillion tons of TNT.
In small telescopes the terraced walls appear very sharp edged and very distinct in nature. In my 14 inch (356mm) Cassegrain – quite the opposite is prevalent – they appear to have rounded edges that slope off gradually to the craters floor. Situated in the center of Copernicus are the rebound peaks that are just off center of the craters 62km in diameter floor. These peaks are comprised of several various sizes – the tallest being around 1.2km above the crater floor. The outer slopes and surrounding ejecta blanket are very extensive. In fact under closer scrutiny you will discover a large amount of smaller craters surrounding Copernicus that were probably caused by secondary impacts from the falling debris.
According to rock samples brought back by Apollo 17 the estimated age of Copernicus is said to be a little over 800 million years old. Backing off on your magnification a little, will reveal that Copernicus has a very large ray system. In fact it is the second largest ray system on the lunar surface, when compared to the crater Tycho. Under close observation you can see that the ray system extends in all directions – some even cross the rays of the neighboring crater Kepler. Of all the regions located on the visible side of the Moon, I like these three the best. I find that when these sites are near the shadow – or terminator – during the phases of the Moon, this is the best time to view them, for if you wait until the terminator has past, or the Moon is near full you will need to use a polarizing filter or a Moon Filter in order to achieve the best results.
One thing is for certain though, the Moon will always provide the observer who is fortunate enough to possess a telescope (or a good set of binoculars), the most breathtaking views of our sister planet that you will ever see, and if you are like me, these views will bring you back time after time.
