Kitt Peak Nightly Observing Program
Splendors of the Universe on YOUR Night!
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Near the lunar south pole, in the rugged Southern Highlands, you can find the second largest crater on the Nearside of the Moon. Clavius looks very oblong, due to heavy foreshortening, but is a 230 km wide circular crater. It is heavily scarred by younger craters
Copernicus is a large, conspicuous crater located in the Oceanus Procellarum (Ocean of Storms). It has extensive rays of ejecta spanning hundreds of kilometers from the rim of the crater. This crater is likely to be only hundreds of millions of years old—young for a lunar crater.
Gassendi is a large, 110 km wide, easy to recognize crater on the northern rim of the Mare Humorum. Gassendi and smaller crater Gassendi A together form a sort of ring-with-gemstone shape, making it easy to pick out the pair amongst all the other craters in the SW quadrant of the Moon. The floor of Gassendi is not very deep, and heavily fractured. Its central peaks are easy to see.
Kepler is one of the most conspicuous craters on the Moon, though it is one of the smaller more conspicuous craters. It has lengthy, bright rays, small central peaks, and slumps of material at the base of its walls. It looks rather like a mini-me of larger crater Copernicus (to its east). Though similar in diameter, it is much deeper than nearby crater Encke
Mairan is a crater located near the northwestern limb of the Moon, in a highland peninsula. To its east is the Mare Imbrium and to its west is the Oceanus Procellarum. It looks elongated, because it is near the limb of the Moon, but is a regular, circular crater. Nearby Mairan T is a lunar dome with steep walls and an oddly shaped crater at its peak.
Proclus is a very bright crater just west of Mare Crisium. Its bright rays radiate in mostly 3 directions. To its west is Palus Somni—the Marsh of Sleep.
Some craters on the Moon look elongated, because they are foreshortened, meaning we are seeing them at an angle. The closer the crater is to the limb of the Moon, the more foreshortened it is. Schiller, however, is actually an elliptical crater—very unusual. It’s hard to be sure how Schiller formed. Notice the linear ridges on one end of the elongated crater, dividing the floor in half, and the small crater on the opposite end, connected to schiller by a valley.
Tycho is a prominent crater on the Moon—but it doesn’t stand out because of its size. At 85 km in diameter it is one of thousands of craters on the Moon its size and larger. Tycho stands out because of its rays. Crater rays are formed by ejecta—dust and debris ejected from the surface during and impact event, that spreads upwards and outwards, and eventually settles back down on the surface to leave behind radial spikes around newly formed craters. Prominent and extensive rays suggest that a crater is fresher, or more recently formed. Tycho may be as young as 108 million years old. That may sound old, but craters on the Moon can remain for billions of years.
Mons Gruithuisen Gamma (left) and Delta (right) are two of many very interesting features found in or near the Mare Imbrium. Southwest of Sinus Iridum, they are more conspicuous than most lunar domes.
Mare Crisium is distinctly seperated from all of the other maria on the near side of the Moon, making it easy to distinguish. This round feature on the Moon is nearing the eastern limb, and so, is severly foreshortened—meaning, we are not looking at it straigh on, but at an angle.
Mare Humorum is one of the smaller mare on the near side of the Moon. It is situated on the western hemisphere, south of Oceanus Procellarum. It is estimated to be about 3.9 billion years old, and is the site of one fo the Moon’s mascons. Mascons, short for mass concentrations) have slightly higher gravity than the are around them. Mare Humorum has some striking ridges and rilles. A prominant crater, Gassendi interupts the northern “coast” of Mare Humorum—its floor cracked with many rilles. Yet another, smaller crater interupts Gassendi’s northern rim—creating a memorable figure of a ring with gemstone.
The Mare Imbrium Impact Basin formed when a large object crashed into the Moon 3.9 billion years ago. subsurface lava rose to flood the giant crater, eventually solidifying into a younger, smoother terrain. Prominent features of Mare Imbrium include the crater Plato to the north, with a dark crater floor; Sinus Iridum (meaning Bay of Rainbows) to the northwest, with the Montes Jura mountain range forming a distinct C-shaped knob on the edge of the mare; and the 3 mountain ranges—Montes Alpes, Caucasus, and Apenninus—that mark the eastern edge of the mare.
Also known as a twilight zone, a terminator is where the shadow of night and the light of day come to meet on a planetary body. At the edge of where the Sun’s light reaches, the terminator is constantly moving as the Moon rotates. When observing the Moon, many features are best observed when they are near the terminator, where shadows are long and plentiful. The shadows provide higher contrast between surface features.
Your Telescope Operator and Guide. Thank you for joining me this evening! See you soon!!
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Nightly Observing Program. Most of the above images were taken as
the Overnight Telescope Observing Program. For more information on this unique experience please visit Overnight Telescope Observing Program.
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