Lunar 100 observing report 24.10.2010

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24.10.2010

Meade Lightbridge 16" F4.5 FL 1829mm

Lunar phase 339.8°

Illumination 96.9%

Clear skies and cold 4°

Number 10 Mare Crisium

Mare Crisium is full of interesting objects, through my 12.5 ortho I could observe wrinkle ridges running from crater Lick northwards to crater Yerkes E and then very faintly continuing to the west of crater Swift. I could also detect a slight darkening of the lava floor north of crater Picard and surrounding crater Peirce. I could a few of the wrinkle ridges that cover the sothern shore called Dorsum Termier.

This is also the site where Luna 15 landed. Luna 15 was launched only three days before the historic Apollo 11 mission to the Moon, was the third Soviet attempt to recover and bring lunar soil back to Earth. Luna 15 entered lunar orbit at 10:00 UT on 17 July 1969. The spacecraft remained in lunar orbit for two days while controllers checked all onboard systems and performed two orbital maneuvers. After completing 86 communications sessions and 52 orbits of the Moon at various inclinations and altitudes it began its descent. Astronauts Armstrong and Aldrin had already set foot on the Moon when Luna 15 fired its main retrorocket engine to initiate descent to the surface at 15:47 UT on 21 July 1969. Unfortunately, transmissions ceased only 4 minutes after deorbit at a calculated altitude of 3 kilometers. The spacecraft impacted the lunar surface on July 21, 1969. The spacecraft had probably crashed onto the side of a mountain. Impact coordinates were 17° north latitude and 60° east longitude in Mare Crisium. It's great using the 6mm ortho to look aroud this famous site and to guess what mountain Luna 15 crashed into.

Number 12 Proclus

Crater Proclus comes form the Copernician (From -1.1 billions years to present days) period of the Moon's history and is a medium size crater at 17 miles in diameter and 7300 feet high. With the 9mm inserted I could make out the impact rays running from Proclus over to the crater Carmichael & Hill.

If you look south-east from Proclus you see the area of Promontorium Olivium, the site of the somewhat infamous O'Neill's Bridge. Luck was with me on this one as the light was just right and I managed to see the famous bridge. It looks like a > < formation, like a bridge narrowing in the middle crossing a large canyon. It was only visible in 12.5 and 9mm ortho's and not in 6mm as the seeing made this impossible. The bridge is made up from the rims of two craters that are side by side, essentially just a trick of the light but one that I enjoyed.

Number 16 Petavius

One of the best craters ever, amazing steep terraced sides and the central peak was stunning, Petavius is 107 miles in diameter and has crater walls 10,000 feet high. I could detect the sunlight bouncing of two higher formations on top of the peak. The Rima Petavius at 48 miles long and only 1 mile wide looked like it was emerging from the central mountain and running westward and was easy to see. I could even detect Petavius A just behind the peak, very stunning indeed best in 9mm ortho.

Number 85 Langrenus Rays

Looked very similar to Petvius but slightly smaller, with the 9mm ortho inserted I could see steep sides and a double central peak, I could see the sunlight casting double peak shadows onto the crater floor. I could also make out 4 rays emerging from crater on to the floor of mare fecunditatis.

Number 58 Rheita Valley

To the south-west of crater Rheita lies the Rheita valley, this looked like a very wide valley heading southwards towards crater Young D. This valley is old coming from the Pre-Imbrian (From -4.55 billions years to -3.85 billions years) period, it is also pretty long at 303 miles long and an impressive 18 miles wide, these measurements are very similar to that of the Grand Canyon here on Earth. Through the 9mm ortho it looked like it was formed from lots of impact craters as the edges of the valley resembled crater walls. But this valley is very impressive and well worth observing.

Number 72 Atlas dark-halo craters

Through the 6mm ortho I could detect a central peak with a Rima Atlas running through the centre and I think two cratlets within the Crater Atlas. the 9mm ortho really made the two volcanic dark spots appear, one was near the northern edge in the 6 oclock position, the other about 10 oclock on the south eastern edge of craters terraced walls.

Number 25 Messier & Messier A

These craters make a striking pair, slightly oval in shape and look deep. Messier A is slightly larger and has a 100 km ejecta ray heading westward accross the Mare Fecunditatis. I tried to find Rima Messier but this was hard and needs to be more on the terminator, Virtual Moon Atlas states you need a scope of at least 500mm. I could make out a fuzzy rima with the 4mm ortho inserted and just a darker smudge with the 12.5mm inserted but no definite rimae was visible.

Number 31 Taruntius

A round and pretty low sided crater, I could see central peak, the northern rim is impacted by crater Cameron, nothing special but another one ticked off the lunar 100 list.